wdiff rfc7455.alt-original rfc7455.txt

TRILL Working group Tissa Senevirathne
Internet Draft Norman Engineering Task Force (IETF) T. Senevirathne
Request for Comments: 7455 N. Finn
Intended status: Standard Track Samer Salam
Updates: 6325 Deepak S. Salam
Category: Standards Track D. Kumar
CISCO

Donald
ISSN: 2070-1721 Cisco
D. Eastlake
Sam 3rd
S. Aldrin
Yizhou
Y. Li
Huawei

October 24, 2014
Expires: April
March 2015

TRILL

Transparent Interconnection of Lots of Links (TRILL): Fault Management
draft-ietf-trill-oam-fm-11.txt

Abstract

This document specifies TRILL OAM Fault Management. Transparent Interconnection of Lots of Links
(TRILL) Operations, Administration, and Maintenance (OAM) fault
management. Methods in this document follow the IEEE 802.1 CFM (Continuity (Connectivity
Fault Management) framework defined in IEEE 802.1 and reuse OAM tools
where possible. Additional messages and TLVs are defined for TRILL TRILL-
specific applications or for cases where a different set of
information is required other than CFM as defined in IEEE 802.1 CFM. 802.1.
This document updates RFC 6325.

Status of this This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

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Internet Standards is inappropriate to use Internet-
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The list Section 2 of RFC 5741.

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This Internet-Draft will expire on April 24, 2009.
http://www.rfc-editor.org/info/rfc7455.

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Table of Contents

1. Introduction ............................................... 4 ....................................................5
2. Conventions used Used in this document .......................... 4 This Document ...............................5
3. General Format of TRILL OAM Packets ........................ 5 .............................6
3.1. Identification of TRILL OAM frames .................... 7 Frames .........................8
3.2. Use of TRILL OAM Alert Flag ........................... 7 ................................8
3.2.1. Handling of TRILL frames Frames with the "A" Flag ....... 8 ..........9
3.3. OAM Capability Announcement ........................... 8 ................................9
3.4. Identification of the OAM message .................... 10 Message .........................10
4. TRILL OAM Layering vs. IEEE Layering ...................... 10 ...........................10
4.1. Processing at the ISS Layer .............................. 12 ...............................12
4.1.1. Receive Processing .............................. 12 .................................12
4.1.2. Transmit Processing ............................. 12 ................................12
4.2. End Station End-Station VLAN and Priority Processing ............. 12 ..................12
4.2.1. Receive Processing .............................. 12 .................................12
4.2.2. Transmit Procession ............................. 12 Processing ................................12
4.3. TRILL Encapsulation and De-capsulation Decapsulation Layer ......... 12 ...............12
4.3.1. Receive Processing for Unicast packets .......... 12 Packets .............12
4.3.2. Transmit Processing for unicast packets ......... 13 Unicast Packets ............13
4.3.3. Receive Processing for Multicast packets ........ 14 Packets ...........14
4.3.4. Transmit Processing of Multicast packets ........ 15 Packets ...........15
4.4. TRILL OAM Layer Processing ........................... 16 ................................15
5. Maintenance Associations (MA) (MAs) in TRILL .................... 17 ........................17
6. MEP Addressing ............................................ 18 .................................................18
6.1. Use of MIP in TRILL .................................. 21 .......................................21
7. Continuity Check Message (CCM) ............................ 23 .................................22
8. TRILL OAM Message Channel ................................. 25 ......................................25
8.1. TRILL OAM Message header ............................. 25 Header ..................................25
8.2. TRILL Specific TRILL-Specific OAM Opcodes ........................... 26 OpCodes ................................26
8.3. Format of TRILL OAM TLV .............................. 26 ...................................26
8.4. TRILL OAM TLVs ....................................... 27 ............................................27
8.4.1. Common TLVs between CFM and TRILL ............... 27 ..................27
8.4.2. TRILL OAM Specific OAM-Specific TLVs ......................... 28 ............................27
8.4.3. TRILL OAM Application Identifier TLV ............ 28 ...............28
8.4.4. Out Of Band Out-of-Band Reply Address TLV ................... 30 ......................30
8.4.5. Diagnostics Diagnostic Label TLV ........................... 31 ...............................31
8.4.6. Original Data Payload TLV ....................... 32 ..........................32
8.4.7. RBridge scope Scope TLV ............................... 32 ..................................32
8.4.8. Previous RBridge nickname Nickname TLV ................... 33 ......................33
8.4.9. Next Hop Next-Hop RBridge List TLV ....................... 34 ..........................34
8.4.10. Multicast Receiver Port count Count TLV .............. 35 .................34
8.4.11. Flow Identifier (flow-id) TLV .................. 35 ...............................35
8.4.12. Reflector Entropy TLV .......................... 36 .............................36
8.4.13. Authentication TLV ............................. 37 ................................37
9. Loopback Message .......................................... 39 ...............................................38
9.1. Loopback OAM Message format .......................... 39 Format ...................................38
9.2. Theory of Operation .................................. 39 .......................................39
9.2.1. Actions by Originator RBridge ................... 39 ......................39
9.2.2. Intermediate RBridge ............................ 40 ...............................39
9.2.3. Destination RBridge ............................. 40 ................................40
10. Path Trace Message ....................................... 41 ............................................40
10.1. Theory of Operation ................................. 42 ......................................41
10.1.1. Action Actions by Originator RBridge ................... 42 .....................41
10.1.2. Intermediate RBridge ........................... 42 ..............................42
10.1.3. Destination RBridge ............................ 44 ...............................43
11. Multi-Destination Tree Verification Message (MTVM) ....... 44 ............43
11.1. Multi-Destination Tree Verification Message (MTVM) MTVM Format .................................................... 44 ..............................................44
11.2. Theory of Operation ................................. 45 ......................................44
11.2.1. Actions by Originator RBridge .................. 45 .....................44
11.2.2. Receiving RBridge .............................. 46 .................................45
11.2.3. In scope In-Scope RBridges .............................. 46 .................................45
12. Application of Continuity Check Message (CCM) in TRILL ... 47 ........46
12.1. CCM Error Notification .............................. 48 ...................................47
12.2. Theory of Operation ................................. 49 ......................................48
12.2.1. Actions by Originator RBridge .................. 49 .....................48
12.2.2. Intermediate RBridge ........................... 50 ..............................49
12.2.3. Destination RBridge ............................ 50 ...............................49
13. Fragmented Reply ......................................... 51 ..............................................49
14. Security Considerations .................................. 51 .......................................50
15. IANA Considerations ...................................... 53 ...........................................52
15.1. OAM Capabilitiy Capability Flags ............................... 53 .....................................52
15.2. CFM Code Points ..................................... 53 ..........................................52
15.3. MAC Addresses ....................................... 54 ............................................53
15.4. Return codes Codes and sub codes .......................... 54 Sub-codes ...............................53
15.5. TRILL RBridge Nickname Address Family ............... 55 ............................54
16. References ............................................... 55 ....................................................54
16.1. Normative References ................................ 55 .....................................54
16.2. Informative References .............................. 56
17. Acknowledgments .......................................... 57 ...................................55
Appendix A. Backwards Compatibility .......................... 58 ...............................57
A.1. Maintenance Point (MEP/MIP) Model ........................57
A.2. Data-Plane Encoding and Frame Identification .............57
Appendix B. Base Mode for TRILL OAM .......................... 61 ...............................59
Appendix C. MAC Addresses Request ............................ 63 .................................61
Acknowledgments ...................................................62
Authors' Addresses ................................................62

1. Introduction

The general structure of TRILL OAM messages is presented in
[RFC7174]. TRILL OAM messages consist of five six parts: link header, Link Header,
TRILL header, flow entropy, Header, Flow Entropy, OAM message channel, Ethertype, OAM Message Channel, and link
trailer.
Link Trailer.

The OAM message channel Message Channel carries various control information and
OAM OAM-
related data between TRILL switches, also known as RBridges or
Routing Bridges.

A common OAM message channel Message Channel representation can be shared between
different technologies. This consistency between different OAM
technologies promotes nested fault monitoring and isolation between
technologies that share the same OAM framework.

The TRILL OAM message channel Message Channel is formatted as specified in IEEE
Connectivity Fault Management (CFM) [8021Q].

The ITU-T Y.1731 [Y1731] standard utilizes the same messaging format
as [8021Q] OAM messages where applicable. This document takes a
similar stance and reuses [8021Q] in TRILL OAM. It is assumed that
readers are familiar with [8021Q] and [Y1731]. Readers who are not
familiar with these documents are encouraged to review them.

This document specifies TRILL OAM fault management. It updates
[RFC6325] as specified in Section 3.1. TRILL performance monitoring
is specified in [RFC7456].

2. Conventions used Used in this document This Document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in
RFC-2119 RFC 2119 [RFC2119].

Capitalized IANA Considerations terms such as "Standards Action" are
to be interpreted as described in [RFC5226].

Acronyms used in the document include the following:

CCM - Continuity Check Message [8021Q]

DA - Destination Address

ECMP - Equal Cost Equal-Cost Multipath

FGL - Fine-Grained Label
ISS - Internal Sub Layer Sub-Layer Service [8021Q]

LBM - Loop Back Loopback Message [8021Q]

LBR - Loop Back Loopback Reply Message [8021Q]

MA - Maintenance Point Association [8021Q] [RFC7174]

MAC - Media Access Control (MAC)

MD - Maintenance Domain [8021Q]

MEP - Maintenance End Point [RFC7174] [8021Q]

MIP - Maintenance Intermediate Point [RFC7174] [8021Q]

MP - Maintenance Association [8021Q] Point [RFC7174]

MD - Maintenance Domain [8021Q]

MTVM - Multi-destination Tree Verification Message

MTVR - Multi-destination Tree Verification Reply Message

OAM - Operations, Administration, and Maintenance [RFC6291]

PRI - Priority of Ethernet Frames [8021Q]

PTM - Path Trace Message

PTR - Path Trace Reply Message

SA - Source Address

SAP - Service Access Point [8021Q]

TRILL - Transparent Interconnection of Lots of Links [RFC6325]

SAP - Service Access Point [8021Q]

3. General Format of TRILL OAM Packets

The TRILL forwarding paradigm allows an implementation to select a
path from a set of equal cost equal-cost paths to forward a unicast TRILL Data
packet. For multi-destination TRILL Data packets, a distribution
tree is chosen by the TRILL switch that ingresses or creates the
packet. Selection of the path of choice is implementation dependent
at each hop for unicast and at the ingress for multi-destination.
However, it is a common practice to utilize Layer 2 through Layer 4
information in the frame payload for path selection.

For accurate monitoring and/or diagnostics, OAM Messages messages are required
to follow the same path as corresponding data packets. [RFC7174]
presents the high-level format of the OAM messages. The details of the
TRILL OAM frame format are defined in this document.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Link Header . (variable) Variable
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ TRILL Header + 6 or more bytes
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Flow Entropy . 96 bytes
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OAM Ethertype |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. OAM Message Channel . Variable
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Trailer | Variable
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1 1: Format of TRILL OAM Messages

o Link Header: Media-dependent header. For Ethernet, this includes
the Destination MAC, Source MAC, VLAN (optional) (optional), and Ethertype
fields.

o TRILL Header: Fixed size of 6 bytes when the Extended Header is
not included [RFC6325] [RFC6325].

o Flow Entropy: This is a 96-byte fixed size A 96-byte, fixed-size field. The rightmost bits of
the field MUST be padded with zeros, up to 96 bytes, when the flow entropy
flow-entropy information is less than 96 bytes. Flow entropy Entropy
enables emulation of the forwarding behavior of the desired data
packets. The Flow Entropy field starts with the Inner.MacDA. The
offset of the Inner.MacDA depends on whether extensions are
included or not as specified in [RFC7179] and [RFC6325]. Such
extensions are not commonly supported in current TRILL
implementations.

o OAM Ethertype: OAM Ethertype is A 16-bit Ethertype that identifies the OAM Message channel
Channel that follows. This document specifies using the Ethertype
0x8902 allocated for CFM [8021Q].

o OAM Message Channel: This is a variable size A variable-size section that carries OAM OAM-
related information. The message format is as specified in
[8021Q].

o Link Trailer: Media-dependent trailer. For Ethernet, this is the
FCS (Frame Check Sequence).

3.1. Identification of TRILL OAM frames Frames

TRILL, as originally specified in [RFC6325], did not have a specific
flag or a method to identify OAM frames. This document updates
[RFC6325] to include specific methods to identify TRILL OAM frames.
Section 3.2. below 3.2 explains the details of the method.

3.2. Use of TRILL OAM Alert Flag

The TRILL Header, as defined in [RFC6325], has two reserved bits.
This document specifies use of the reserved bit next to the Version
field in the TRILL header Header as the Alert flag. The Alert flag will be
denoted by "A". RBridges MUST NOT use the "A" flag for forwarding
decisions such as the selection of which ECMP path or multi-
destination tree to select.

Implementations that comply with this document MUST utilize the "A"
flag and CFM Ethertype to identify TRILL OAM frames.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| V |A|R|M|Op-Length| Hop Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Egress RBridge Nickname | Ingress RBridge Nickname |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options...
+-+-+-+-+-+-+-+-+-+-+-+-

Figure 2 2: TRILL Header with the "A" Flag

o A (1 bit) - bit): Indicates this is a possible OAM frame and is subject
to specific handling as specified in this document.

All other TRILL Header fields carry the same meaning as defined in RFC6325.
[RFC6325].

3.2.1. Handling of TRILL frames Frames with the "A" Flag

Value

The value "1" in the A "A" flag indicates TRILL frames that may qualify
as OAM frames. Implementations are further REQUIRED to validate such
frames by comparing the value at the OAM Ethertype (Figure 1)
location with the CFM Ethertype "0x8902" [8021Q]. If the value
matches, such frames are identified as TRILL OAM frames and SHOULD be
processed as discussed in Section 4.

Frames with the "A" flag set that do not contain a CFM Ethertype are
not considered as OAM frames. Such frames MUST be silently discarded.

OAM capable

OAM-capable RBridges MUST NOT generate OAM frames to an RBridge that
is not OAM capable.

Intermediate RBridges, RBridges that are not OAM capable (i.e. (i.e., do not
understand the "A" flag) follow the process defined in [RFC6325]
section Section 3.3 of
[RFC6325] and forward OAM frames with the "A" flag unaltered.

3.3. OAM Capability Announcement

Any given RBridge can be (1) OAM incapable or incapable, (2) OAM capable with new extensions
extensions, or (3) OAM capable with backwards-compatible the backwards-compatibility
method. The OAM request originator, prior to origination of the
request
request, is required to identify the OAM capability of the target and
generate the appropriate OAM message.

Capability

The capability flags defined in the TRILL version Version sub-TLV (TRILL-VER)
[RFC7176] will be utilized for announcing OAM capabilities. The
following OAM related OAM-related capability flags are defined:

O - OAM Capable capable

B - Backwards Compatible Backwards-compatible OAM

A capability announcement, announcement with the "O" Flag flag set to 1 and the "B" flag
set to 1, 1 indicates that the originating RBridge is OAM capable but
utilizes the backwards compatible backwards-compatibility method defined in Appendix A. A
capability announcement with the "O" Flag flag set to 1 and the "B" flag
set to 0, 0 indicates that the originating RBridge is OAM capable and
utilizes the method specified in section Section 3.2.

When the "O" Flag flag is set to 0, the announcing implementation is
considered not capable of OAM OAM, and the "B" flag is ignored.

Figure 3 3: TRILL-VER sub-TLV Sub-TLV [RFC7176] with O "O" and B flags

Capability flags "B" Flags

In Figure 3, "A" is the Affinity sub-TLV support flag as indicated in
[RFC7176], and "F" are defined by [RFC7176] is the FGL-safe flag as indicated in [RFC7172] and
[RFC7172].
[RFC7176]. The "O" and "B" Flags flags are located after the "F" flag in
the Capability and Header Flags field of the TRILL-VER sub-TLV, as
depicted in Figure 3 above. Usage of the "O" and "B" flags are as is
discussed above.

Absence of the TRILL-VER sub-TLV means the announcing RBridge is not
OAM capable.

3.4. Identification of the OAM message Message

The ingress RBridge nickname allows recipients to identify the origin
of the message in most cases. However, when an out of band out-of-band reply is
generated, the responding RBridge nickname is not easy to identify.

The [8021Q] Sender ID TLV (1) provides methods to identify the device
by including the chassis Chassis ID. The Chassis ID allows different
addressing formats such as IANA Address Family enumerations. IANA
has allocated Address Family Number 16396 for TRILL RBridge nickname. In
TRILL OAM OAM, the Chassis ID subtype sub-type of the Sender ID TLV is set to 16396
16396, and the Chassis ID field contains the corresponding TRILL RBridge
nickname.

When the Sender ID TLV is present and chassis sub type the Chassis ID sub-type is set
to 16396, the sender RBridge TRILL nickname SHOULD be derived from
the nickname embedded in the Chassis ID. Otherwise, the sender
RBridge TRILL nickname SHOULD be derived from the ingress RBridge
nickname.

4. TRILL OAM Layering vs. IEEE Layering

This section presents the placement of the TRILL OAM shim within the
IEEE 802.1 layers. The Transmit transmit and Receive receive processing are
explained.

Figure 4 4: Placement of TRILL MP within IEEE 802.1

[RFC6325]

[RFC6325], Section 4.6 as updated by [RFC7180] provides a detailed
explanation of frame processing. Please refer to those documents for
additional details and for processing scenarios not covered herein.

Sections 4.1 and 4.2 below apply to links using a broadcast LAN technology
such as Ethernet.

On links using an inherently point-to-point technology, such as PPP
[RFC6361], there is no Outer.MacDA, Outer.MacSA, or Outer.VLAN
because these are part of the link header Link Header for Ethernet. Point-to-point Point-to-
point links typically have link headers Link Headers without these fields.

4.1. Processing at the ISS Layer

4.1.1. Receive Processing

The ISS Layer layer receives an indication from the port. It extracts
DA, SA DA
and SA, and it marks the remainder of the payload as M1. The ISS Layer
layer passes on (DA, SA, M1) as an indication to the higher layer.

For TRILL Ethernet frames, this is Outer.MacDA and Outer.MacSA. M1
is the remainder of the packet.

4.1.2. Transmit Processing

The ISS layer receives an indication from the higher layer that
contains (DA, SA, M1). It constructs an Ethernet frame and passes
down to the port.

4.2. End Station End-Station VLAN and Priority Processing

4.2.1. Receive Processing

Receives

Receive (DA, SA, M1) indication from the ISS Layer. Extracts layer. Extract the VLAN
ID and priority from the M1 part of the received indication (or
derive them from the port defaults or other default parameters) and constructs
construct (DA, SA, VLAN, PRI, M2). VLAN+PRI+M2
map maps to M1 in the
received indication. Pass (DA, SA, VLAN, PRI, M2) to the TRILL encap/decap procession
Encapsulation/Decapsulation layer.

4.2.2. Transmit Procession Processing

Receive (DA, SA, VLAN, PRI, M2) indication from the TRILL encap/decap
processing
Encapsulation/Decapsulation layer. Merge VLAN, PRI, M2 to form M1.
Pass down (DA, SA, M1) to the ISS processing Layer. layer.

4.3. TRILL Encapsulation and De-capsulation Decapsulation Layer

4.3.1. Receive Processing for Unicast packets Packets

o Receive indication (DA, SA, VLAN, PRI, M2) from End Station the End-Station
VLAN and Priority Processing Layer. layer.

o If the DA matches the port Local DA and Frame the frame is of TRILL Ethertype
.
Ethertype:

- Discard DA, SA, VLAN, and PRI. From M2, derive (TRILL-HDR,
iDA, iSA, i-VL, M3)

. M3).

- If TRILL nickname is Local and TRILL-OAM Flag TRILL Header Alert flag is set set:

* Pass on to OAM processing

. Else processing.

- Else, pass on (TRILL-HDR, iDA, iSA, i-VL, M3) to the RBridge
Layer
layer.

o If the DA matches the port Local DA and EtherType the Ethertype is RBridge-Channel
[RFC7178]

. RBridge-
Channel [RFC7178]:

- Process as a possible unicast native RBridge Channel packet packet.

o If the DA matches the port Local DA and the Ethertype is neither
TRILL nor RBridge-Channel

. RBridge-Channel:

- Discard packet packet.

o If the DA does not match and match, the port is Appointed Forwarder for VLAN
VLAN, and the Ethertype is not TRILL or RBridge-Channel

. RBridge-Channel:

- Insert TRILL-Hdr TRILL-HDR and send (TRILL-HDR, iDA, iSA,i-VL, M3)
indication to the RBridge Layer <- This layer (this is the TRILL Ingress
Function.
Function).

4.3.2. Transmit Processing for unicast packets Unicast Packets

o Receive indication (TRILL-HDR, iDA, iSA, iVL, M3) from the RBridge Layer
layer.

o If the egress TRILL nickname is local

o local:

- If the port is Appointed Forwarder for iVL and iVL, the port is not
configured as a trunk or p2p port and (TRILL point-to-point (P2P) port, the TRILL
Alert
Flag set flag is set, and the OAM Ethertype present) then

. is present, then:

* Strip TRILL-HDR and construct (DA, SA, VLAN, M2)
<- This (this is
the TRILL Egress Function. Function).

o Else

. Else:

* Discard packet packet.

o If the egress TRILL nickname is not local
o local:

- Insert Outer.MacDA, Outer.MacSA, Outer.VLAN, and TRILL
Ethertype
Ethertype, and construct (DA, SA, VLAN, M2). Where M2) where M2 is
(TRILL-HDR, (TRILL-
HDR, iDA, iSA, iVL, M) M).

o Forward (DA, SA, V, M2) to the End-Station VLAN End Station processing
Layer. and Priority
Processing layer.

4.3.3. Receive Processing for Multicast packets Packets

o Receive (DA, SA, V, M2) from the End-Station VLAN aware end station
processing layer and Priority
Processing layer.

o If the DA is All-RBridges and the Ethertype is TRILL

o TRILL:

- Strip DA, SA SA, and V. From M2, extract (TRILL-HDR, iDA, iSA, iVL
iVL, and M3).

- If the TRILL Alert Flag flag is set and the OAM Ethertype is present
at the end of Flow entropy

. Entropy:

* Perform OAM Processing

o Else processing.

- Else, extract the TRILL header, Header, inner MAC addresses addresses, and
inner VLAN
Inner.VLAN, and pass indication (TRILL-HDR, iDA, iSA, iVL and
M3) to the TRILL RBridge Layer layer.

o If the DA is All-IS-IS-RBridges and the Ethertype is L2-IS-
IS L2-IS-IS,
then pass frame up to TRILL IS-IS processing processing.

o If the DA is All-RBridges or All-IS-IS-RBridges but the Ethertype
is not TRILL or L2-IS-IS respectively

o respectively:

- Discard the packet packet.

o If the Ethertype is TRILL but the multicast DA is not All-
RBridges; All-RBridges
or if the Ethertype is L2-IS-IS but the multicast DA is not All-IS-IS-RBridges

o All-
IS-IS-RBridges:

- Discard the packet packet.

o If the DA is All-Edge-RBridges and the Ethertype is RBridge-Channel
[RFC7178]

o RBridge-
Channel [RFC7178]:

- Process as a possible multicast native RBridge Channel packet packet.

o If the DA is in the initial bridging/link protocols block
(01-80-C2-00-00-00 to 01-80-C2-00-00-0F) or is in the TRILL block
and not assigned for Outer.MacDA use (01-80-C2-00-00-
42 (01-80-C2-00-00-42 to 01-80-C2-00-00-4F) then

o
01-80-C2-00-00-4F), then:

- The frame is not propagated through an RBridge although some
special processing may be done at the port as specified in [RFC6325]
[RFC6325], and the frame may be dispatched to Layer 2
processing at the port if certain protocols are supported by
that port (examples: (examples include the Link Aggregation
Protocol, Link Layer Protocol and
the Link-Layer Discovery Protocol).

o If the DA is some other multicast value

o value:

- Insert TRILL-HDR and construct (TRILL-HDR, iDA, iSA, IVL, M3)

o M3).

- Pass the (TRILL-HDR, iDA, iSA, IVL, M3) to the RBridge Layer layer.

4.3.4. Transmit Processing of Multicast packets Packets

The following ignores the case of transmitting TRILL IS-IS packets.

o Receive indication (TRILL-HDR, iDA, iSA, iVL, M3) from the RBridge
layer.

o If TRILL-HDR the TRILL Header multicast ("M") flag set and is set, the TRILL-HDR
Alert flag
set is set, and the OAM Ethertype present is present, then:

- Construct (DA, SA, V, M2) by inserting TRILL Outer.MacDA of All-
RBridges,
All-RBridges, Outer.MacSA, Outer.VLAN Outer.VLAN, and TRILL Ethertype. M2
here is (Ethertype TRILL, TRILL-HDR, iDA, iSA, iVL,
M)

NOTE: Second M).

Note: A second copy of native format is not made.

o Else If TRILL-HDR Else, if the TRILL Header multicast ("M") flag is set and the
Alert flag not set

o set:

- If the port is appointed Appointed Forwarder for iVL and the port is not
configured as a trunk port or a p2p P2P port, Strip strip TRILL-HDR, iSA,
iDA, and iVL and construct (DA, SA, V, M2) for native format.

- Make a second copy (DA, SA, V, M2) by inserting TRILL
Outer.MacDA, Outer.MacSA, Outer.VLAN Outer.VLAN, and TRILL Ethertype. M2
here is (Ethertype TRILL, TRILL-HDR, iDA, iSA, iVL, M) M).

o Pass the indication (DA, SA, V, M2) to End Station the End-Station VLAN
processing and
Priority Processing layer.

4.4. TRILL OAM Layer Processing

The TRILL OAM Processing Layer layer is located between the TRILL
Encapsulation / De-capsulation
Encapsulation/Decapsulation layer and the RBridge Layer. layer. It performs
the following: 1. Identification of 1) identifies OAM frames that need local processing
and 2. 2) performs OAM processing or redirect redirects to the CPU for OAM
processing.

o Receive indication (TRILL-HDR, iDA, iSA, iVL, M3) from the RBridge
layer. M3 is the payload after inner VLAN Inner.VLAN iVL.

o If the TRILL Multicast Flag Header multicast ("M") flag is set and set, the TRILL Alert Flag
flag is
set set, and TRILL OAM Ethertype is present then
o present, then:

- If MEP or MIP is configured on the Inner.VLAN/FGL of the
packet then
. discard
packet, then:

* Discard packets that have MD-LEVEL Less MD-Level less than that of the MEP
or packets that do not have MD-LEVEL MD-Level present (e.g., due to
packet truncation).
.

* If MD-LEVEL MD-Level matches MD-LEVEL MD-Level of the MEP then
. Re-direct MEP, then:

+ Redirect to OAM Processing processing (Do not forward
further)
. further).

* If MD-LEVEL MD-Level matches MD-LEVEL MD-Level of MIP then
. MIP, then:

+ Make a Copy copy for OAM processing and continue
. continue.

* If MD-LEVL MD-Level matches MD-LEVEL MD-Level of MEP then
. MEP, then:

+ Redirect the OAM packet to OAM processing and do not
forward along or forward as a native packet.

o Else Else, if the TRILL Alert Flag flag is set and the TRILL OAM Ethertype
is
present then
o present, then:

- If MEP or MIP is configured on the Inner.VLAN/FGL of the
packet then
. discard
packet, then:

* Discard packets that have MD-LEVEL MD-Level not present or
MD-LEVEL where MD-
Level is Less less than that of the MEP.
.

* If MD-LEVEL MD-Level matches MD-LEVEL MD-Level of the MEP then
. Re-direct MEP, then:

+ Redirect to OAM Processing (Do processing (do not forward
further)
. further).

* If MD-LEVEL MD-Level matches MD-LEVEL MD-Level of MIP then
. MIP, then:

+ Make a Copy copy for OAM processing and continue continue.

o Else // Non-OAM Packet
o Continue Else, for a non-OAM packet:

- Continue.

o Pass the indication (DA, SA, V, M2) to End Station the End-Station VLAN
processing and
Priority Processing layer.

NOTE:

Note: In the Receive receive path, the processing above compares against with the
Down MEP and MIP Half functions. In the transmit processing processing, it
compares against with Up MEP and MIP Half functions.

Appointed Forwarder is a function that the TRILL Encap/De-Cap
Encapsulation/Decapsulation layer performs. The TRILL Encap/De-cap Layer
Encapsulation/Decapsulation layer is responsible for prevention of
leaking of OAM packets as native frames.

5. Maintenance Associations (MA) (MAs) in TRILL

[8021Q] defines a maintenance association Maintenance Association as a logical relationship
between a group of nodes. Each Maintenance Association (MA) is
identified with a unique MAID of 48 bytes [8021Q]. CCM and other
related OAM functions operate within the scope of an MA. The
definition of MA is technology independent.
Similarly Similarly, it is encoded
within the OAM message, not in the
technology dependent technology-dependent portion of
the packet. Hence Hence, the MAID as defined in [8021Q] can be utilized
for TRILL OAM, OAM without modifications. This also allows us to utilize
CCM and LBM messages defined in [8021Q], [8021Q] as is.

In TRILL, an MA may contain two or more RBridges (MEPs). For
unicast, it is likely that the MA contains exactly two MEPs that are
the two end-points end points of the flow. For multicast, the MA may contain
two or more MEPs.

For TRILL, in addition to all of the standard [8021Q] CFM MIB
definitions, each MEP's MIB contains one or more flow entropy Flow Entropy
definitions corresponding to the set of flows that the MEP monitors.

[8021Q] CFM MIB is augmented to add the TRILL specific TRILL-specific information.
Figure 5, below 5 depicts the augmentation of the CFM MIB to add the TRILL TRILL-
specific Flow Entropy.

MA---
|
--- MEP
|
. - Remote MEP List
.
|
--- MEP-A
|
--- MEP-B
.

|
. - Flow Entropy List { Augments IEEE8021-CFM-MIB}

|
--- (Flow Entropy-1)
|
--- (Flow-entropy-2) (Flow Entropy-2)
|
. --- (Flow Entropy n) Entropy-n)
|
Other MIB entries

Figure 5 5: Correlation of TRILL augmented TRILL-Augmented MIB

The detailed TRILL OAM MIB will be specified in a separate document
[TRILLOAMMIB].

6. MEP Addressing

In IEEE CFM [8021Q], OAM messages address the target MEP by utilizing
a unique MAC address. In TRILL TRILL, a MEP is addressed by a combination
of the egress RBridge nickname and the Inner
VLAN/FGL. Inner.VLAN/FGL.

Additionally, MEPs are represented by 2 octet a 2-octet MEP-ID that is
independent of the underlying technology. In CFM [8021Q] [8021Q], the value
of MEP-ID is restricted to the range of 1 to 8191. However, on a CFM
[8021Q] packet, MEP-ID MEP-IDs are encoded as a 2 octet 2-octet field. In the TRILL
Base Mode operation presented in Appendix B B, MEP-IDs are mapped 1
to 1
1-to-1 with the RBridge nicknames. Hence, In in TRILL, a MEP-ID MUST be
a number in the range from 1 to 65535.

At the MEP, OAM packets go through a hierarchy of op-code de-
multiplexers. OpCode
demultiplexers. The op-code de-multiplexers OpCode demultiplexers channel the incoming OAM
packets to the appropriate message processor (e.g. LBM) The
reader may refer (e.g., LBM). Refer to
Figure 6 below for a visual depiction of these different de-multiplexers. demultiplexers.

The demultiplexing sequence is as follows:

1. Identify the packets that need OAM processing at the Local local
RBridge as specified in Section 4.

a. Identify the MEP that is associated with the Inner.VLAN/FGL.

2. The MEP first validates the MD-LEVEL MD-Level and then then:

a. Redirect Redirects to MD-LEVEL De-multiplexer the MD-Level demultiplexer.

3. MD-LEVEL de-multiplexer The MD-Level demultiplexer compares the MD-Level of the packet
against the MD level MD-Level of the local MEPs of a given MD-Level on the port
port. (Note: there can be more than one MEP at the same MD-
Level MD-Level
but belonging they belong to different MAs) MAs.)

a. If the packet MD-LEVEL MD-Level is equal to the configured MD-
LEVEL MD-Level of
the MEP, then pass to the Opcode de-multiplexer OpCode demultiplexer.

b. If the packet MD-LEVEL MD-Level is less than the configured MD-
LEVEL MD-Level
of the MEP, discard the packet packet.

c. If the packer MD-LEVEL packet MD-Level is greater than the configured
MD-LEVEL
MD-Level of the MEP, then pass on to the next higher MD-
LEVEL de-multiplexer, next-higher MD-Level
demultiplexer, if available. Otherwise, if no such higher MD-LEVEL de-multiplexer
MD-Level demultiplexer exists, then forward the packet as
normal data.

4. Opcode De-multiplexer The OpCode demultiplexer compares the opcode OpCode in the packet with
supported opcodes OpCodes.

a. If Op-code the OpCode is CCM, LBM, LBR, PTM, PTR, MTVM, or MTVR, then
pass on to the correct Processor processor.

b. If Op-code the OpCode is Unknown, unknown, then discard.

|
.CCM LBM PTM MTVM . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+
| OP Code DE-Mux |--- Unknown
+-+-+-+-+-+-+-+-+-+-+-+-+
^ ^ ^
MD==Li | | |
+-+-+ +-+-+ +-+-+
| L |-->|L2 |-.- |Ln |---- >
+-+-+ +-+-+ +-+-+ |
| ^ | | |
MD<LI Drop | Drop Drop |
| |
MD not --- |TRILL OAM need local |
Present | Processing |
| |
TRILL Data ---- TRILL Data ----
------->| T |----------------- >| M |--- >
+ TRILL OAM ---- + pass through OAM ----

Figure 6 6: OAM De-Multiplexers Demultiplexers at MEP for active Active SAP

T :

o T: Denotes Tap, that identifies Tap. Identifies OAM frames that need local processing.
These are the packets with the Alert flag set and OAM Ethertype is
present after the flow entropy Flow Entropy of the
packet

M : Is the post processing merge, packet.

o M: The post-processing merge that merges data and OAM messages
that are passed through. Additionally, the Merge merge component
ensures, as explained earlier, that OAM packets are not forwarded
out as native frames.

L :

o L: Denotes MD-Level processing. Packets with whose MD-Level is less
than the Level MD-Level of the current processing step will be dropped.
Packets with equal MD-Level MD-Levels are passed on to the opcode de-multiplexer. OpCode
demultiplexer. Others are passed on to the next level next-level MD
processors or eventually to the merge point (M).

NOTE: LBM, LBR, MTVM, MTVR, PTM PTM, and PTR are not subject to MA de-multiplexers.
demultiplexers. These packets do not have an MA encoded in the
packet. Adequate response can be generated to these packets, without
loss of functionality, by any of the MEPs present on that interface
or an entity within the RBridge.

6.1. Use of MIP in TRILL

Maintenance Intermediate Points (MIP) (MIPs) are mainly used for fault
isolation. Link Trace Messages in [8021Q] utilize a well-known
multicast MAC address address, and MIPs generate responses to Link Trace
messages.
Messages. Response to Link Trace messages Messages or lack thereof can be
used for fault isolation in TRILL.

As explained in section 10. , Section 10, a hop-count Hop Count expiry approach will be
utilized for fault isolation and path tracing. The approach is very
similar to the well-known IP trace-route approach. Hence, explicit
addressing of MIPs is not required for the purpose of fault
isolation.

Any given RBridge can have multiple MIPs located within an interface.
As such, a mechanism is required to identify which MIP should respond
to an incoming OAM message. Any MIP residing within the ingress
interface may reply to the incoming Path Trace
message Message without loss
of functionality or information. As specified in Section 3.4. , 3.4, the
address of the responding RBridge can be identified by means of the
Sender ID TLV (1). The Reply Ingress TLV (5) identifies the
interface id. The combination of these allows the recipient of the
response to uniquely identify the responder.

A similar approach to that presented above for MEPs can be used for
MIP processing. It is important to note that "M", the merge block of
a MIP, does not prevent OAM packets leaking out as native frames. On
edge interfaces, MEPs MUST be configured to prevent the leaking of
TRILL OAM packets out of the TRILL Campus. campus.

PTM PTR MTVM MTVR
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OP Code De-Mux |-> Unknown
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
^ ^ ^
MD==Li | | |
+-+-+ +-+-+ +-+-+
| L |- >|L2 |-.- |Ln |------+
+-+-+ +-+-+ +-+-+ |
^ |
| |
Drop | |
MD not --- |TRILL OAM |
Present | |
| v
TRILL Data ---- TRILL Data -----
------- >| T |------------------ >| M |---->
+ TRILL OAM ---- ----

Figure 7 7: OAM De-Multiplexers Demultiplexers at MIP for active Active SAP

o T: TAP Tap processing for MIP. All packets with OAM the TRILL Header
Alert flag set are captured.

L : MD Level Processing, Packet

o L: MD-Level Processing. Packets with matching MD Level MD-Levels are
"copied" to the Opcode de-multiplexer OpCode demultiplexer, and the original packet is
passed on to the next MD level MD-Level processor. Other packets are
simply passed on to the next MD level processor, MD-Level processor without copying to
the OP code de-multiplexer.

M : Merge processor, OpCode demultiplexer.

o M: The intermediate point processing merge OAM packets to be forwarded along with
the that merges data flow. and
OAM messages that are passed through.

Packets that carry Path Trace Message (PT) (PTM) or Multi-destination Tree
Verification Message (MTVM) OpCodes are passed on to the respective
processors.

Packets with unknown OpCodes are counted and discarded.

7. Continuity Check Message (CCM)

CCMs are used to monitor connectivity and configuration errors.
[8021Q] monitors connectivity by listening to periodic CCM messages
received from its remote MEP partners in the MA. An [8021Q] MEP
identifies cross-connect errors by comparing the MAID in the received
CCM message with the MEP's local MAID. The MAID [8021Q] is a 48-byte
field that is technology independent. Similarly, the MEPID MEP-ID is a
2-byte field that is independent of the technology. Given this
generic definition of CCM fields, CCM as defined in [8021Q] can be
utilized in TRILL with no changes.
TRILL specific TRILL-specific information may be
carried in CCMs when encoded using TRILL specific TRILL-specific TLVs or sub-TLVs.
This is possible since CCMs may carry optional TLVs.

Unlike classical Ethernet environments, TRILL contains multipath
forwarding. The path taken by a packet depends on the payload of the
packet. The Maintenance Association (MA) identifies the interested
end-points
Maintenance End Points (MEPs) of a given monitored path. For unicast
unicast, there are only two MEPs per MA. For multicast multicast, there can be
two or more MEPs in the MA. The entropy values of the monitored
flows are defined within the MA. CCM transmit logic will utilize
these flow
entropy Flow Entropy values when constructing the CCM packets. Please
see
section 12. below Section 12 for the theory of operation of CCM.

The MIB of in [8021Q] is augmented with the definition of flow-
entropy. Flow Entropy.
Please see [TRILLOAMMIB] for definition of these this and other TRILL related TRILL-related OAM MIB
definitions. The below Figure 8 depicts the correlation between MA, CCM CCM, and
the flow-entropy. Flow Entropy.

MA---
|
--- MEP
|
. - Remote MEP List
.
|
--- MEP-A
|
--- MEP-B
.

|
. - Flow Entropy List {Augments IEEE8021-CFM-MIB}

|
--- (Flow Entropy-1)
|
--- (Flow-entropy-2) (Flow Entropy-2)
|
. ---(Flow Entropy n) Entropy-n)
|
. - CCM
|
--- (standard 8021ag entries)
|
--- (hop-count) (Hop Count) { Augments IEEE8021-CFM-MIB}
|
--- (Other TBD (Any other TRILL OAM specific OAM-specific entries)
{Augmented}
|
.
|
- Other MIB entries

Figure 8 8: Augmentation of CCM MIB in TRILL

In a multi-pathing environment, a Flow - flow, by definition - definition, is
unidirectional. A question may arise as to what flow entropy Flow Entropy should
be used in the response. CCMs are unidirectional and have no
explicit reply; as such, the issue of the response flow
entropy Flow Entropy does
not arise. In the transmitted CCM, each MEP reports local status
using the Remote Defect Indication (RDI) flag. Additionally, a MEP
may raise SNMP TRAPs [TRILLOAMMIB] as Alarms alarms when a connectivity
failure occurs.

8. TRILL OAM Message Channel

The TRILL OAM Message Channel can be divided into two parts: TRILL
OAM Message message header and TRILL OAM Message TLVs. Every OAM
Message message MUST
contain a single TRILL OAM message header and a set of one or more
specified OAM Message message TLVs.

8.1. TRILL OAM Message header Header

As discussed earlier, a common messaging framework between [8021Q],
TRILL, and other similar standards such as Y.1731 is accomplished by re-using
reusing the OAM message header defined in [8021Q].

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MD-L | Version | OpCode | Flags |FirstTLVOffset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Opcode Specific OpCode-Specific Information .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. TLVs .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 9 9: OAM Message Format

o MD-L: Maintenance Domain Level (3 bits). Identifies the
maintenance domain level. For TRILL, in general,
this field is set to a single value across the TRILL campus. When
using the TRILL base mode Base Mode as specified in Appendix B, MD-L is set
to 3. However, extension of TRILL, for example TRILL (for example, to support
multilevel,
multilevel) may create different MD-LEVELs MD-Levels, and the MD-L field
must be appropriately set in those scenarios. (Please refer to
[8021Q] for the definition of MD-Level) MD-Level).

o Version: Indicates the version (5 bits) as specified in [8021Q].
This document does not require changing the Version defined in
[8021Q].

o OpCode: Operation Code (8 bits). Specifies the operation
performed by the message. See Section 8.2.

o Flags: Includes operational flags (1 byte). The definition of
flags is Opcode-specific OpCode-specific and is covered in the applicable
sections.

o FirstTLVOffset: Defines the location of the first TLV, in bytes,
starting from the end of the FirstTLVOffset field (1 byte).
(Refer to [8021Q] for the definition of the FirstTLVOffset.)

o OpCode-Specific Information: May contain Session Identification
Number, timestamp, etc.

The MD-L, Version, Opcode, Flags OpCode, Flags, and FirstTLVOffset fields
collectively are referred to as the OAM Message Header.

The Opcode specific information section of the OAM Message may
contain Session Identification number, time-stamp, etc. message header.

8.2. TRILL Specific TRILL-Specific OAM Opcodes OpCodes

The following TRILL specific TRILL-specific CFM Opcodes OpCodes are defined. Each of the
Opcodes
OpCodes indicates a separate type of TRILL OAM message. Details of
the messages are presented in the related sections. Sections 10 and 11.

TRILL OAM Message Opcodes:

TBD1: message OpCodes:

64: Path Trace Reply
TBD2:
65: Path Trace Message
TBD3: Multicast
66: Multi-destination Tree Verification Reply
TBD4: Multicast
67: Multi-destination Tree Verification Message

Loopback and CCM Messages reuse the opcodes OpCodes defined by [8021Q] [8021Q].

8.3. Format of TRILL OAM TLV

The same CFM TLV format as defined in [8021Q] is used for TRILL OAM.
The following figure depicts the general format of a TRILL OAM TLV:

0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Value(variable) Value (variable) .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 10 10: TRILL OAM TLV

o Type (1 octet): Specifies the Type type of the TLV (see sections 8.4. Section 8.4 for
TLV types).

o Length (2 octets): Specifies the length of the 'Value' Value field in
octets. Length of the 'Value' Value field can be either zero or more octets.

o Value (variable): The length and the content of this field depend
on the type of the TLV. Please refer to applicable TLV definitions
for the details.

Semantics and usage of Type values allocated for TRILL OAM purpose
are defined by this document and other future related documents.

8.4. TRILL OAM TLVs

TRILL related

TRILL-related TLVs are defined in this section. [8021Q] TLVS defined
TLVs in
[8021Q] are reused, where applicable.

8.4.1. Common TLVs between CFM and TRILL

The following TLVs are defined in [8021Q]. We re-use reuse them where
applicable. The format and semantics of the TLVs are as defined in
[8021Q].

Type Name of TLV in [8021Q]
---- ----------------------
0 End TLV
1 Sender ID TLV
2 Port Status TLV
3 Data TLV
4 Interface Status TLV
5 Reply Ingress TLV
6 Reply Egress TLV
7 LTM Egress Identifier TLV
8 LTR Egress Identifier TLV
9-30 Reserved
31 Organization Specific TLV

8.4.2. TRILL OAM Specific OAM-Specific TLVs

Listed below is a summary of TRILL OAM TLVs and their corresponding
codes. Format and semantics of TRILL OAM TLVs are defined in
subsequent sections.

Type TLV Name
----------- ----------------------
TBDa
---- ------------------------------------
64 TRILL OAM Application Identifier TLV
TBDb Out of Band
65 Out-of-Band Reply Address TLV
TBDc
66 Diagnostic Label TLV
TBDd
67 Original Data Payload TLV
TBDe
68 RBridge scope Scope TLV
TBDf
69 Previous RBridge nickname Nickname TLV
TBDg Next Hop
70 Next-Hop RBridge List (ECMP) TLV
TBDh
71 Multicast Receiver Port count Count TLV
TBDi
72 Flow Identifier TLV
TBDj
73 Reflector Entropy TLV
TBDk
74 Authentication TLV

The TRILL OAM Application Identifier TLV (TBDa) (64) MUST be the first TLV.
An End TLV (0) MUST be included as the last TLV. All other TLVs can
be included in any order.

8.4.3. TRILL OAM Application Identifier TLV

The TRILL OAM Application Identifier TLV carries information specific
to TRILL OAM
application specific information. applications. The TRILL OAM Application Identifier TLV
MUST always be present and MUST be the first TLV in TRILL OAM
messages. Messages that do not include the TRILL OAM Application
Identifier TLV as the first TLV MUST be discarded by a TRILL MP.

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved1 | Fragment-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Return Code |Return sub-code| Sub-code| Reserved2 |F|C|O|I|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 11 11: TRILL OAM Application Identifier TLV

o Type (1 octet) = TBDa indicate that this is the octet): 64, TRILL OAM Application Identifier TLV. TLV

o Length (2 octets) = 9.

TRILL OAM octets): 9

o Version (1 octet), currently octet): Currently set to zero. Indicates the TRILL OAM
version. The TRILL OAM version can be different than the [8021Q]
version.

o Reserved1 (3 octets): set Set to zero on transmission and ignored on
reception.

o Fragment-ID (1 octet): Indicates the fragment number of the
current message. This applies only to reply messages; in request
messages
messages, it must be set to zero on transmission and ignored on
receipt. F The "F" flag defined below MUST be set with the final message
message, whether it is the last fragment of the fragmented message
or the only message of the reply. Section 13. below 13 provides more
details on OAM Message message fragmentation.

o Return Code (1 octet): Set to zero on requests. Set to an
appropriate value in response messages.

o Return sub-code Sub-code (1 Octet): Return sub-code is set octet): Set to zero on transmission of request
message. The Return sub-code Sub-code identifies categories within a
specific Return code. Return sub-code Code and MUST be interpreted within a Return code. Code.

o Reserved2 (12 bits): Set to zero on transmission and ignored on
reception.

o F (1 bit): Final flag, when flag. When set, indicates this is the last
response.

o C (1 bit): Cross connect error flag(VLAN/Label Cross-Connect Error flag (VLAN/FGL mapping error), if
set error). If
set, indicates that the label (VLAN/FGL) in the flow entropy Flow Entropy is
different than the label included in the diagnostic Diagnostic Label TLV.
This field is ignored in request messages and MUST only be
interpreted in response messages.

o O (1 bit): If set, indicates, indicates OAM out-of-band response requested.

o I (1 bit): If set, indicates, indicates OAM in-band response requested.

NOTE: When both O and I bits are set to zero, this indicates that no
response is required (silent mode). User Users MAY specify both O and I
or I,
one of them them, or none. When both O and I bits are set set, the response
is sent both in-band and out-of-band.

8.4.4. Out Of Band Out-of-Band Reply Address TLV

Out of Band

The Out-of-Band Reply Address TLV specifies the address to which an
out of band
out-of-band OAM reply message MUST be sent. When the O bit in the
TRILL Version TLV sub-TLV (Section 3.3) is not set, Out of Band the Out-of-Band Reply
Address TLV is ignored.

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Address Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Addr Length | |
+-+-+-+-+-+-+-+-+ |
| |
. Reply Address .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 12 Out of Band IP 12: Out-of-Band Reply Address TLV

o Type (1 octet) = TBDb octet): 65, Out-of-Band Reply Address TLV

o Length (2 octets) = octets): Variable. Minimum length is 2 + the length (in
octets) of the shortest address. Currently Currently, the minimum value of
this field is 4, but this could change in the future if a new
address shorter than the TRILL RBridge nickname is defined.

o Address Type (1 octet) = octet):

0 - IPv4. IPv4

1 - IPv6. IPv6

2 - TRILL RBridge
nickname. nickname

All other values reserved.

o Addr Length (1 octet) = octet): Depends on the Address Type. Currently Currently,
defined values are:

4 - IPv4. IPv4

16 - IPv6, IPv6

2 - TRILL RBridge
nickname. nickname

Other lengths may be acceptable for future Address Types.

o Reply Address (variable): Address where the reply needed needs to be
sent. Length depends on the address specification.

8.4.5. Diagnostics Diagnostic Label TLV

The Diagnostic label Label TLV specifies the data label (VLAN or FGL) in
which the OAM messages are generated. Receiving RBridge MUST compare
the data label of the Flow entropy Entropy to the data label specified in the
Diagnostic Label TLV. Label Error Flag The "C" flag (Cross Connect Error) in the
response (TRILL OAM Message Version TLV) Application Identifier TLV; Section 8.4.3) MUST
be set when the two VLANs do not match.

Figure 13 13: Diagnostic VLAN Label TLV

o Type (1 octet) = TBDc indicates that this is the TRILL octet): 66, Diagnostic
VLAN Label TLV

o Length (2 octets) = octets): 5

o L-Type (Label type, 1 octet)

0- indicate (1 octet): Label type

0 - Indicates a right-justified 802.1Q 12 bit VLAN. 12-bit VLAN padded on the
left with bits that must be sent as zero and ignored on
receipt

1 - indicate Indicates a TRILL 24 bit fine grain 24-bit fine-grained label

o Reserved (1 octet) = set octet): Set to zero on transmission and ignored on
reception.

o Label (24 bits)= bits): Either 12 bit 12-bit VLAN or 24 bit fine grain fine-grained label.

RBridges do not perform Label label error checking when the Diagnostic
Label TLV is not included in the OAM message. In certain deployments
deployments, intermediate devices may perform label translation. In
such scenarios, the originator should not include the diagnostic Diagnostic
Label TLV in OAM messages. Inclusion of diagnostic Diagnostic Label TLV will
generate unwanted label error notifications.

8.4.6. Original Data Payload TLV

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. Original Payload .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 14 14: Original Data Payload TLV

o Type (1 octet) = TBDd octet): 67, Original Data Payload TLV

o Length (2 octets) = octets): variable

o Original Payload: The original TRILL Header and Flow Entropy.
Used in constructing replies to the Loopback Message (see Section
9) and the Path Trace Message (see Section 10).

8.4.7. RBridge scope Scope TLV

The RBridge scope Scope TLV identifies nicknames of RBridges from which a
response is required. The RBridge scope Scope TLV is only applicable to
Multicast
Multi-destination Tree Verification messages. Messages. This TLV SHOULD NOT be
included in other messages. Receiving RBridges MUST ignore this TLV
on messages other than Multicast Multi-destination Tree Verification Message. Messages.

Each TLV can contain up to 255 nicknames of in-scope RBridges. A
Multicast
Multi-destination Tree Verification Message may contain multiple "RBridge
RBridge scope TLVs", TLVs, in the event that more than 255 in scope in-scope RBridges
need to be specified.

Absence of the "RBridge scope TLV" RBridge Scope TLV indicates that a response is needed
from all the RBridges. Please see section 11. Section 11 for details.

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | nOfnicknames |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| nickname-1 Nickname-1 | nickname-2 Nickname-2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | nickname-n Nickname-n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 15 15: RBridge Scope TLV

o Type (1 octet) = TBDe indicates that this is the "RBridge scope
TLV" octet): 68, RBridge Scope TLV

o Length (2 octets) = variable. octets): Variable. Minimum value is 1.

o nOfnicknames (1 octet) = indicates octet): Indicates the number of nicknames included
in this TLV. Zero (0) indicates no nicknames are included in the
TLV. When this field is set to zero (0), length the Length field MUST be
set to 1.

o Nickname (2 octets) = 16 bit octets): 16-bit RBridge nickname. nickname

8.4.8. Previous RBridge nickname Nickname TLV

The "Previous Previous RBridge nickname TLV" Nickname TLV identifies the nickname or
nicknames of the Previous previous RBridge. [RFC6325] allows a given RBridge
to hold multiple nicknames.

The "Previous Previous RBridge nickname TLV" Nickname TLV is an optional TLV. Multiple
instances of this TLV MAY be included when an upstream RBridge is
represented by more than 255 nicknames (highly unlikely).

Figure 16 16: Previous RBridge nickname Nickname TLV

o Type (1 octet) = TBDf indicates that this is the "Previous octet): 69, Previous RBridge nickname" Nickname TLV

o Length (2 octets) = 5. octets): 5
o Reserved (3 octet) = set octet): Set to zero on transmission and ignored on
reception.

o Nickname (2 octets) = octets): RBridge nickname. nickname

8.4.9. Next Hop Next-Hop RBridge List TLV

"Next Hop

The Next-Hop RBridge List TLV" TLV identifies the nickname or nicknames of
the downstream next hop next-hop RBridges. [RFC6325] allows a given RBridge
to have multiple Equal Cost Paths equal-cost paths to a specified destination. Each next hop
next-hop RBridge is represented by one of its nicknames.

"Next Hop

The Next-Hop RBridge List TLV" TLV is an optional TLV. Multiple instances
of this TLV MAY be included when there are more than 255 Equal Cost Paths equal-cost
paths to the destination.

Figure 17 Next Hop 17: Next-Hop RBridge List TLV

o Type (1 octet) = TBDg indicates that this is the "Next nickname" octet): 70, Next-Hop RBridge List TLV

o Length (2 octets) = variable. octets): Variable. Minimum value is 1.

Nickname (2 octets) = 16 bit RBridge nickname.

o Nickname (2 octets): 16-bit RBridge nickname.

8.4.10. Multicast Receiver Port count Count TLV

"Multicast

The Multicast Receiver Port Count TLV" TLV identifies the number of ports
interested in receiving the specified multicast stream within the
responding RBridge on the label (VLAN or FGL) specified by the
Diagnostic Label TLV.

The Multicast Receiver Port count Count TLV is an Optional optional TLV.

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| number Number of Receivers |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 18 18: Multicast Receiver Availability Port Count TLV

o Type (1 octet) = TBDh indicates that this is the "Multicast
Availability TLV" octet): 71, Multicast Receiver Port Count TLV

o Length (2 octets) = 5. octets): 5

o Reserved (1 octet) = set octet): Set to zero on transmission and ignored on
reception.

o Number of Receivers (4 octets) = octets): Indicates the number of
Multicast multicast
receivers available on the responding RBridge on the label
specified by the diagnostic label.

8.4.11. Flow Identifier (flow-id) TLV

The Flow Identifier (flow-id) TLV uniquely identifies a specific flow. The flow-id
flow-identifier value is unique per MEP and needs to be interpreted
as such.

Figure 19 19: Flow Identifier TLV

o Type (1 octet) = TBDi octet): 72, Flow Identifier TLV

o Length (2 octets) = 5. octets): 5

o Reserved (1 octet) set octet): Set to 0 on transmission and ignored on
reception.

o MEP-ID (2 octets) = octets): MEP-ID of the originator [8021Q]. In TRILL TRILL,
MEP-ID can take a value from 1 to 65535.

Flow-id

o flow-identifier (2 octets) = uniquely octets): Uniquely identifies the flow per MEP.
Different MEPs may allocate the same flow-id flow-identifier value. The
{MEP-ID,
flow-id} flow-identifier} pair is globally unique.

Inclusion of the MEP-ID in the flow-id Flow Identifier TLV allows the
inclusion of a MEP-ID for messages that do not contain a MEP-ID in
their OAM header. Applications may use MEP-ID information for
different types of troubleshooting.

8.4.12. Reflector Entropy TLV

The Reflector Entropy TLV is an optional TLV. This TLV, when
present, tells the responder to utilize the Reflector Entropy
specified within the TLV as the flow-entropy of the response message.

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Reflector Entropy .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 20 20: Reflector Entropy TLV

o Type (1 octet) = TBDj octet): 73, Reflector Entropy TLV. TLV

o Length (2 octets) = 97. octets): 97

o Reserved (1 octet) = set octet): Set to zero on transmission and ignored by the
recipient.

o Reflector Entropy (96-octet) = (96 octets): Flow Entropy to be used by the
responder. May be padded with zero zeros if the desired flow entropy flow-entropy
information is less than 96 octets.

8.4.13. Authentication TLV

The Authentication TLV is an optional TLV that can appear in any OAM Message
message or Reply reply in TRILL.

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Auth Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Authentication Value .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 21: Authentication TLV

o Type (1 octet) = TBDk octet): 74, Authentication TLV. TLV

o Length (2 octets) = variable length octets): Variable

o The Auth Type and following Authentication Value are the same as
the Auth Type and following value for the [IS-IS] Authentication
TLV. It is RECOMMENDED that Auth Type 3 be used. Auth Types 0,
1, 2, and 54 MUST NOT be used. With Auth Type 3, the
Authentication TLV is as follows:

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Auth Type = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ .
. Authentication Data (variable) .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 22: Authentication TLV with Auth Type 3

With Auth Type 3, the process is generally as specified in [RFC5310]
using the same Key ID space as TRILL [IS-IS]. The area covered by
the Authentication TLV is from the beginning of the TRILL Header to
the end of the TRILL OAM Message Channel - Channel; the Link Header and Trailer
are not included. The TRILL Header Alert
and Alert, Reserved bit bit, and Hop
Count are treated as if zero for the purposes of computing and verifying
the Authentication Data.

Key distribution is out of the scope for of this document as the keying
distributed for IS-IS is used.

An RBridge supporting OAM authentication can be configured to either
(1) ignore received OAM Authentication TLVs and not send them, (2)
ignore received OAM Authentication TLVs but include them in all OAM
packets sent, or (3) to include Authentication TLVs in all OAM
messages sent and enforce authentication of OAM messages received.
When an RBridge is enforcing authentication, it discards any OAM
message subject to OAM processing that does not contain an
Authentication TLV or if the an Authentication TLV does not verify.

9. Loopback Message

9.1. Loopback OAM Message format Format

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MD-L | Version | OpCode | Flags |FirstTLVOffset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loopback Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. TLVs .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 21 23: Loopback OAM Message Format

The above figure above depicts the format of the Loopback Request and
response
Response messages as defined in [8021Q]. The Opcode OpCode for the Loopback
Message is set to 3 3, and the Opcode OpCode for the Reply Message reply message is set to 2
[8021Q]. The Loopback Transaction Identifier (commonly called the
Session Identification Number or Session ID in this document) is a
32-bit integer that allows the requesting RBridge to uniquely
identify the corresponding session. Responding RBridges, without
modification, MUST echo the received "Loopback Transaction
Identifier" number.

9.2. Theory of Operation

9.2.1. Actions by Originator RBridge

The originator RBridge takes the following actions:

o Identifies the destination RBridge nickname based on user
specification or based on the specified destination MAC or IP
address.

o Constructs the flow entropy Flow Entropy based on user specified user-specified parameters or
implementation specific
implementation-specific default parameters.

o Constructs the TRILL OAM header: sets the opcode OpCode to Loopback
message
Message type (3)[8021Q]. (3) [8021Q]. Assigns applicable Loopback Transaction
Identifier number for the request.

o The TRILL OAM Application Identifier TLV MUST be included and with the
flags set to applicable values.

Include

o Includes following OAM TLVs, where applicable

o Out of Band applicable:

- Out-of-Band Reply Address TLV

- Diagnostic Label TLV

- Sender ID TLV

Specify

o Specifies the Hop count Count of the TRILL data Data frame per user
specification or utilize an applicable Hop count Count value.

Dispatch

o Dispatches the OAM frame for transmission.

RBridges may continue to retransmit the request at periodic
intervals, intervals
until a response is received or the re-transmission retransmission count expires. At
each transmission transmission, the Session Identification number Number MUST be
incremented.

9.2.2. Intermediate RBridge

Intermediate RBridges forward the frame as a normal data frame
and frame; no
special handling is required.

9.2.3. Destination RBridge

If the Loopback message Message is addressed to the local RBridge and
satisfies the OAM identification criteria specified in section
3.1. then, Section 3.1,
then the RBridge data plane forwards the message to the CPU for
further processing.

The TRILL OAM application layer further validates the received OAM
frame by checking for the presence of OAM-Ethertype OAM Ethertype at the end of the flow entropy.
Flow Entropy. Frames that do not contain OAM-Ethertype OAM Ethertype at the end of
the flow entropy Flow Entropy MUST be discarded.

Construction of the TRILL OAM response:

o The TRILL OAM application encodes the received TRILL header Header and flow
entropy
Flow Entropy in the Original payload Data Payload TLV and includes it in
the OAM message.

o Set the Return Code to (1) "Reply" and Return sub code Sub-code to zero (0)
"Valid Response". Update the TRILL OAM opcode OpCode to 2 (Loopback
Message Reply) Reply).

o Optionally, if the VLAN/FGL identifier value of the received flow
entropy Flow
Entropy differs from the value specified in the diagnostic Label, Diagnostic Label
TLV, set the Label Error Flag on "C" flag (Cross Connect Error) in the TRILL OAM
Application Identifier TLV.

o Include the sender Sender ID TLV (1) (1).

o If in-band response was requested, dispatch the frame to the TRILL
data plane with request-originator RBridge nickname as the egress
RBridge nickname.

o If out-of-band response was requested, dispatch the frame to the
IP forwarding process.

10. Path Trace Message

The primary use of the Path Trace Message is for fault isolation. It
may also be used for plotting the path taken from a given RBridge to
another RBridge.

[8021Q] accomplishes the objectives of the TRILL Path Trace Message
using Link Trace Messages. Link Trace Messages utilize a well-known
multicast MAC address. This works for [8021Q], [8021Q] because
for 802.1 both the
unicast and multicast paths are congruent. However, in TRILL TRILL,
multicast and unicast are not congruent. Hence, TRILL OAM uses a new
message format: the Path Trace message. Message.

The Path Trace Message has the same format as the Loopback Message.
The Opcode OpCode for Path Trace Reply is TBD1 64, and the OpCode for the Path
Trace Message is TBD2. 65.

Operation of the Path Trace message Message is identical to the Loopback
message
Message except that it is first transmitted with a TRILL Header Hop count
Count field value of 1. The sending RBridge expects an "Intermediate
RBridge" Return sub-code Sub-code from the next hop or a "Valid response"
Return sub-Code Sub-code response from the destination RBridge. If an
"Intermediate RBridge" Return sub-code Sub-code is received in the response,
the originator RBridge records the information received from the
intermediate node that generated the message and resends the message
by incrementing the previous Hop
count Count value by 1. This process is
continued until, a response is received from the destination RBridge or RBridge,
a Path Trace process timeout occur occurs, or the Hop count Count reaches a
configured maximum value.

10.1. Theory of Operation

10.1.1. Action Actions by Originator RBridge

Identify

The originator RBridge takes the following actions:

o Identifies the destination RBridge based on user specification or
based on location of the specified MAC address.

Construct

o Constructs the flow entropy Flow Entropy based on user specified user-specified parameters or
implementation specific
implementation-specific default parameters.

Construct

o Constructs the TRILL OAM header: Set set the opcode OpCode to Path Trace
Request message
Message type (TBD2). (65). Assign an applicable Session Identification
number for the request. Return-code Return Code and sub-code Return Sub-code MUST be
set to zero.

o The TRILL OAM Application Identifier TLV MUST be included and set with the
flags set to applicable values.

Include

o Includes the following OAM TLVs, where applicable

o Out of Band applicable:

- Out-of-Band Reply Address TLV

- Diagnostic Label TLV

o Include the

- Sender ID TLV

Specify

o Specifies the Hop count Count of the TRILL data Data frame as 1 for the first
request.

Dispatch

o Dispatches the OAM frame to the TRILL data plane for transmission.

An RBridge may continue to retransmit the request at periodic
intervals,
intervals until a response is received or the re-transmission retransmission count
expires. At each new re-transmission, retransmission, the Session Identification
number MUST be incremented. Additionally, for responses received
from intermediate RBridges, the RBridge nickname and interface
information MUST be recorded.

10.1.2. Intermediate RBridge

Path Trace Messages transit through Intermediate RBridges
transparently, unless Hop-count the Hop Count has expired.

The TRILL OAM application layer further validates the received OAM
frame by examining the presence of the TRILL Alert Flag flag and OAM- OAM
Ethertype at the end of the flow entropy Flow Entropy and by examining the MD
Level.
MD-Level. Frames that do not contain OAM-Ethertype OAM Ethertype at the end of the
flow entropy
Flow Entropy MUST be discarded.

Construction of the TRILL OAM response:

o The TRILL OAM application encodes the received TRILL header Header and flow
entropy
Flow Entropy in the Original payload Data Payload TLV and include includes it in
the OAM message.

o Set the Return Code to (1) "Reply" and Return sub code Sub-code to zero two (2)
"Intermediate RBridge". Update the TRILL OAM opcode OpCode to TBD1 64 (Path
Trace Reply).

o If the VLAN/FGL identifier value of the received flow entropy Flow Entropy
differs from the value specified in the diagnostic Label, label, set the
Label Error Flag on
"C" flag (Cross Connect Error) in the TRILL OAM Application
Identifier TLV.

o Include the following TLVs TLVs:

- Previous RBridge nickname Nickname TLV (69)

- Reply Ingress TLV (5)

- Reply Egress TLV (6)

- Interface Status TLV (4)

TRILL Next Hop

- Next-Hop RBridge List TLV (70) (Repeat for each ECMP) (70)

- Sender ID TLV (1)
o If Label a cross-connect error is detected, set C the "C" flag (Label error detected) (Cross-
Connect Error) in the
version. reply's TRILL OAM Application Identifier
TLV.

o If in-band response was requested, dispatch the frame to the TRILL
data plane with request-originator RBridge nickname as the egress
RBridge nickname.

o If out-of-band response was requested, dispatch the frame to the
standard IP forwarding process.

10.1.3. Destination RBridge

Processing is identical to section 10.1.2. With that in Section 10.1.2 with the exception
that the TRILL OAM Opcode OpCode is set to Path Trace Reply (TBD1). (64).

11. Multi-Destination Tree Verification Message (MTVM)

Multi-Destination

Multi-destination Tree Verification messages Messages allow verifying TRILL
distribution tree integrity and pruning. TRILL VLAN/FGL and
multicast pruning are described in [RFC6325] [RFC7180] [RFC6325], [RFC7180], and
[RFC7172]. Multi-destination tree verification Tree Verification and Multicast
group verification messages Group
Verification Messages are designed to detect pruning defects.
Additionally, these tools can be used for plotting a given multicast
tree within the TRILL campus.

Multi-Destination tree verification

Multi-destination Tree Verification OAM frames are copied to the CPU
of every intermediate RBridge that is part of the distribution tree
being verified. The originator of the Multi-
destination Multi-destination Tree verification message
Verification Message specifies the scope of RBridges from which a
response is required. Only the RBridges listed in the scope field
respond to the request. Other RBridges silently discard the request.
Inclusion of the scope parameter field is required to prevent receiving an
excessive number of responses. The typical scenario of distribution
tree verification or group
verification, verification involves verifying multicast
connectivity to a selected set of end-nodes end nodes as opposed to the entire
network. Availability of the scope facilitates narrowing down the
focus to only the RBridges of interest.

Implementations MAY choose to rate-limit CPU bound CPU-bound multicast traffic.
As a result of rate-limiting or due to other congestion conditions,
MTVM messages may be discarded from time to time by the intermediate RBRidges
RBridges, and the requester may be required to retransmit the
request. Implementations SHOULD narrow the embedded scope of
retransmission request requests only to RBridges that have failed to respond.

11.1. Multi-Destination Tree Verification Message (MTVM) Format MTVM Format

The format of MTVM is identical to that of the Loopback Message format
defined in section 9. Section 9 with the exception that the Op-Code OpCode used is
TBD4. 67.

11.2. Theory of Operation

11.2.1. Actions by Originator RBridge

The user is required required, at a minimum minimum, to specify either the
distribution trees that need to be verified, or the Multicast MAC
address and VLAN/FGL, or the VLAN/FGL and Multicast destination Destination IP
address. Alternatively, for more specific multicast flow
verification, the user MAY specify more information e.g. information, e.g., source MAC
address, VLAN/FGL, and Destination and Source IP addresses.
Implementations, at a minimum, must allow the user to specify a
choice of distribution trees, Destination Multicast MAC address address, and
VLAN/FGL that needs to be verified. Although, Although it is not mandatory, it
is highly desired to provide an option to specify the scope. It
should be noted that the source MAC address and some other parameters
may not be specified if the Backwards
Compatibility Method of backwards-compatibility method in
Appendix A is used to identify the OAM frames.

Default parameters MUST be used for unspecified parameters. Flow
entropy
Entropy is constructed based on user specified user-specified parameters and/or
default parameters.

Based on user specified parameters, the originating RBridge does the
following:

o Identifies the nickname that represents the multicast tree.

o Obtains the applicable Hop count Count value for the selected multicast
tree.

o Constructs TRILL OAM message header and include includes the Session
Identification number. The Session Identification number facilitate Number
facilitates the originator mapping the response to the correct
request.

o Includes the TRILL OAM Application Identifier TLV, which MUST be
included.

o Includes the Op-Code OpCode Multicast Tree Verification Message
(TBD4) (67).

o Includes RBridge scope Scope TLV (TBDe) (68).

o Optionally, include includes the following TLV, TLVs, where applicable

o Out-of-band applicable:

- Out-of-Band IP address (TBDb)
o Address TLV (65)

- Diagnostic Label (TBDd)

o TLV (66)

- Sender ID TLV (1)

Specify

o Specifies the Hop count Count of the TRILL data Data frame per user
specification or alternatively utilize utilizes the applicable Hop count Count
value if the TRILL Hop count Count is not being specified by the user; and

Dispatch user.

o Dispatches the OAM frame to the TRILL data plane to be ingressed
for transmission.

The RBridge may continue to retransmit the request at a periodic
interval until either a response is received or the re-
transmission retransmission
count expires. At each new re-transmission, retransmission, the Session
Identification number Number MUST be incremented. At each re-
transmission, retransmission,
the RBridge may further reduce the scope to the RBridges that it has
not received a response from.

11.2.2. Receiving RBridge

Receiving RBridges identify multicast verification frames per the
procedure explained in sections Section 3.2.

The RBridge validates the frame and analyzes the scope RBridge list.
If the RBridge scope Scope TLV is present and the local RBridge nickname is
not specified in the scope list, it will silently discard the frame.
If the local RBridge is specified in the scope list OR the RBridge scope
Scope TLV is absent, the receiving RBridge proceeds with further
processing as defined in section Section 11.2.3.

11.2.3. In scope In-Scope RBridges

Construction of the TRILL OAM response:

o The TRILL OAM application encodes the received TRILL header Header and flow
entropy
Flow Entropy in the Original payload Data Payload TLV and includes them in
the OAM message.

o Set the Return Code to zero (0) and Return sub code Sub-code to zero (0).
Update the TRILL OAM opcode OpCode to TBD3 (Multicast 66 (Multi-destination Tree
Verification Reply).

o Include following TLVs:

- Previous RBridge nickname Nickname TLV (TBDf) (69)

- Reply Ingress TLV (5)

- Interface Status TLV (4)

TRILL Next Hop

- Next-Hop RBridge List (TBDg) TLV (70)

- Sender ID TLV (1)

- Multicast Receiver Availability Port Count TLV (TBDh) (71)

o If a Label (VLAN or FGL) cross connect VLAN/FGL cross-connect error is detected, set the
C "C" flag (Cross connect error detected)
(Cross-Connect Error) in the TRILL OAM Application Identifier TLV.

o If in-band response was requested, dispatch the frame to the TRILL
data plane with request-originator RBridge nickname as the egress
RBridge nickname.

o If out-of-band response was requested, dispatch the frame to the
standard IP forwarding process.

12. Application of Continuity Check Message (CCM) in TRILL

Section 7. 7 provides an overview of CCM Messages defined in [8021Q] and
how they can be used within the TRILL OAM. This
section, section presents the
application and Theory theory of Operations operations of CCM within the TRILL OAM
framework. Readers are referred to [8021Q] for CCM message format
and applicable TLV definitions and usages. Only the TRILL specific TRILL-specific
aspects are explained below.

In TRILL, between any two given MEPs MEPs, there can be multiple potential
paths. Whereas in [8021Q], there is always a single path between any
two MEPs at any given time. [RFC6905] requires solutions to have the
ability to monitor continuity over one or more paths.

CCM Messages are uni-directional, such that there is no explicit
response to a received CCM message. Connectivity status is indicated
by setting the applicable flags (e.g. (e.g., RDI) of the CCM messages
transmitted by an a MEP.

It is important that the solution presented in this document
accomplishes the requirements specified in [RFC6905] within the
framework of [8021Q] in a straightforward manner and with minimum
changes. Section 8 above defines multiple flows within the CCM object,
each corresponding to a flow that a given MEP wishes to monitor.
Hence, CCM, in multipath environments like TRILL, monitors per flow per-flow
connectivity and cross connect cross-connect errors.

Receiving MEPs do not cross check cross-check whether a received CCM belongs to a
specific flow from the originating RBridge. Any attempt to track
status of individual flows may explode the amount of state
information that any given RBridge has to maintain.

The obvious question arises: How how does the originating RBridge know
which flow or flows are at fault?

This is accomplished with a combination of the RDI flag in the CCM
header, flow-id Flow Identifier TLV, and SNMP Notifications (Traps).
Section
12.1. below discuss 12.1 discusses the procedure.

12.1. CCM Error Notification

Each MEP transmits 4 four CCM messages per each flow. ([8021Q] detects
CCM fault when 3 three consecutive CCM messages are lost). Each CCM
Message
message has a unique sequence number (Session ID) and unique
flow-identifier. flow-
identifier. The flow identifier flow-identifier is included in the OAM message via flow-id
the Flow Identifier TLV.

When an a MEP notices a CCM timeout from a remote MEP (MEP-A), it sets
the RDI flag on the next CCM message it generates. Additionally, it
logs and sends an SNMP notification that contain contains the remote MEP
Identification, flow-id flow-identifier, and the Sequence Number sequence number of the last
CCM message it received and received, and, if available, the flow-id flow-identifier and
the Sequence Number sequence number of the first CCM message it received after the
failure. Each MEP maintains a unique flow-id flow-identifier per each
flow, hence flow;
hence, the operator can easily identify flows that correspond to the
specific flow-id. flow-identifier.

The following example illustrates the above.

Assume there are two MEPs, MEPs: MEP-A and MEP-B.

Assume there are 3 three flows between MEP-A and MEP-B.

Let's assume MEP-A allocates sequence numbers as follows follows:

Flow-1 Sequence={1,2,3,4,13,14,15,16,.. } flow-id=(1) flow-identifier=(1)

Flow-2 Sequence={5,6,7,8,17,18,19,20,.. } flow-id=(2) flow-identifier=(2)

Flow-3 Sequence={9,10,12,11,21,22,23,24,.. } flow-id=(3) flow-identifier=(3)
Let's Assume assume Flow-2 is at fault.

MEP-B,

MEP-B receives CCM from MEP-A with sequence numbers 1,2,3,4, 1, 2, 3, and 4
but did not receive 5,6,7,8. 5, 6, 7, and 8. CCM timeout is set to 3 three CCM
intervals in [8021Q]. Hence Hence, MEP-B detects the error at the 8'th 8th CCM
message. At this time time, the sequence number of the last good CCM
message MEP-B has received from MEP-A is 4 4, and flow-id the flow-identifier
of the last good CCM Message is (1). Hence Hence, MEP-B will generate a
CCM error SNMP notification with MEP-A and Last MEP-A, last good flow-id (1) flow-identifier
(1), and sequence number 4.

When MEP-A switches to flow-3 Flow-3 after transmitting flow-2, Flow-2, MEP-B will
start receiving CCM messages. In the foregoing example example, it will be a
CCM message with Sequence Numbers 9,10,11,12,21 sequence numbers 9, 10, 11, 12, and 21 and so on.
When in receipt of a new CCM message from a specific MEP, after a CCM
timeout, the TRILL OAM will generate an SNMP Notification of CCM
resume with remote MEP-ID and MEP-ID, the first valid
flow-id flow-identifier, and the Sequence
sequence number after the CCM timeout. In the foregoing example, it
is MEP-A, flow-id (3) flow-identifier (3), and Sequence Number sequence number 9.

The remote MEP list under the CCM MIB Object is augmented to contain
"Last Sequence Number", flow-id flow-identifier, and "CCM Timeout" variables. Last
"Last Sequence Number Number" and flow-id flow-identifier are updated every time a
CCM is received from a remote MEP. The CCM Timeout variable is set
when the CCM timeout occurs and is cleared when a CCM is received.

12.2. Theory of Operation

12.2.1. Actions by Originator RBridge

Derive

The originator RBridge takes the flow entropy following actions:

o Derives the Flow Entropy field based on flow entropy flow-entropy information
specified in the CCM Management object.

Construct

o Constructs the TRILL CCM OAM header as specified in [8021Q].

o The TRILL OAM Version Application Identifier TLV MUST be included as the
first TLV and set with the flags set to applicable values.

Include

o Includes other TLVs specified in [8021Q]

Include [8021Q].

o Includes the following optional TLV, where applicable

o applicable:

- Sender ID TLV (1)
Specify

o Specifies the Hop count Count of the TRILL data Data frame per user
specification or utilize an applicable Hop count Count value.

Dispatch

o Dispatches the OAM frame to the TRILL data plane for transmission.

An RBridge transmits a total of 4 four requests, each at CCM
retransmission interval. At each transmission transmission, the Session
Identification number MUST be incremented by one.

At the 5'th 5th retransmission interval, flow entropy of the Flow Entropy of the CCM
packet is updated to the next flow entropy flow-entropy information specified in
the CCM Management Object. object. If the current flow entropy Flow Entropy is the last flow
entropy
Flow Entropy specified, move to the first flow entropy Flow Entropy specified and
continue the process.

12.2.2. Intermediate RBridge

Intermediate RBridges forward the frame as a normal data frame
and frame; no
special handling is required.

12.2.3. Destination RBridge

If the CCM Message is addressed to the local RBridge or multicast and
satisfies the OAM identification methods specified in sections
3.2. Section 3.2,
then the RBridge data plane forwards the message to the CPU for
further processing.

The TRILL OAM application layer further validates the received OAM
frame by examining the presence of OAM-Ethertype OAM Ethertype at the end of the flow entropy.
Flow Entropy. Frames that do not contain OAM-Ethertype OAM Ethertype at the end of
the flow entropy Flow Entropy MUST be discarded.

Validate

The TRILL OAM application layer then validates the MD-LEVEL MD-Level and pass
the packet to the Opcode de-
multiplexer. OpCode demultiplexer. The Opcode de-multiplexer OpCode demultiplexer
delivers CCM packets to the CCM process.

The CCM Process process performs the processing specified in [8021Q].

Additionally

Additionally, the CCM process updates the CCM Management Object object with
the sequence number of the received CCM packet. Note: The last
received CCM sequence number and CCM timeout are tracked per each
remote MEP.

If the CCM timeout is true for the sending remote MEP, then clear the
CCM timeout in the CCM Management object and generate the SNMP
notification as specified above.

13. Fragmented Reply

TRILL OAM allows Fragmented fragmented reply messages. In case of Fragmented
Replies, fragmented
replies, all part parts of the reply MUST follow the procedure defined in
this section.

The same session Session Identification Number MUST be included in all
related fragments of the same message.

The TRILL OAM Application Identifier TLV MUST be included, with
fragment-ID the
Fragment-ID field monotonically increasing with each fragment
transmitted with the appropriate Final Flag flag field. The Final
Flag, MUST, flag
MUST only be equal to one on the final fragment of the reply.

On the receiver, the process MUST order the fragments based on the
fragment id.
Fragment-ID. Any fragments received after the final fragment MUST be
discarded. Messages with incomplete fragments (i.e. (i.e., messages with
one or missing fragments after the receipt of the fragment with the
final flag set) MUST be discarded as well.

If the number of fragments exceed exceeds the maximum supported fragments
(255), then return code the Return Code of the reply message MUST be set according to the message 1
(Reply message), and return sub code the Return Sub-code MUST be set to 1 indicating fragment (Fragment
limit
exceed. exceeded).

14. Security Considerations

Forged OAM packets could cause false error or failure indications
or indications,
mask actual errors or failures failures, or be used for denial of service.
Source addresses for messages can be forged and the Out
of Band out-of-band reply
facility (Section (see Section 8.4.4) provides for explicitly supplying the
address for replies. For protection against forged OAM packets, the
Authentication TLV (see Section 8.4.13) can be used in an OAM message
in TRILL. This TLV is virtually identical to the IS-IS
Authentication TLV specified in [IS-IS] and depends on IS-IS keying
material and the current state of IS-IS keying and the use of the
virtually identical IS-IS Authentication TLV is analyzed as discussed in
[KARPISIS].
[KARPISIS] and [RFC5310]. In particular, there is currently no
standardized IS-
IS IS-IS automated key management.

Of course, authentication is ineffective unless verified and
ineffective against senders who have the keying material needed to
produce OAM messages that will pass authentication checks.
Implementations MUST implement rate-limiting functionality to protect
against exploitation of OAM messages as a means of denial
of service denial-of-service
attacks. Aggressive rate limiting rate-limiting may trigger false positive errors
against CCM and LBM based LBM-based session monitoring.

Even with authentication, replay of authenticated messages may be
possible. There are four types of messages: Continuity Check (CCM),
Loopback, Path Trace, and Multi-Destination Multi-destination Tree Verification (MTVM).
In the case of CCM messages, sequence numbers are required (see
Section 12.1) that can protect against replay. In the case of
Loopback Messages (see Section 9.1), a Loopback Transaction
Identifier is included that, as required by [8021Q], is incremented
with each transmission and can detect replays. Path Trace Messages PTMs (see Section 10)
and MTVM MTVMs (see
section Section 11.1) are specified to have the same format, although
with a different OpCodes, format as the
Loopback Message and Messages (although with different OpCodes), so they also
have an identifier increment incremented with each transmission that can detect
replays. Thus Thus, all TRILL OAM messages have a field that can be used
for replay protection.

For general TRILL related TRILL-related security considerations, please refer to
[RFC6325].

[8021Q] requires that the MEP filters or pass passes through OAM messages
based on the MD-Level. The MD-Level is embedded deep in the OAM
message. Hence, conventional methods of frame filtering may not be
able to filter frames based on the MD-Level. As a result, OAM
messages that must be dropped due to MD level MD-Level mismatch may leak into
a TRILL domain with a different MD-Level.

This leaking may not cause any functionality loss. The receiving
MEP/MIP is required to validate the MD-level prior to acting on the
message. Any frames received with an incorrect MD-Level need to be
dropped.

Generally, a single operator manages each TRILL campus, hence campus; hence, there
is no risk of security exposure. However, in the event of
multi multi-
operator deployments, operators should be aware of possible exposure
of device specific information device-specific information, and appropriate measures must be
taken.

It is also important to note that the MPLS OAM [RFC4379] framework [RFC4379]
does not include the concept of domains and OAM filtering based on
operators. It is our opinion that the lack of OAM frame filtering
based on domains does not introduce significant functional deficiency
or security risk.

It is possible to mandate requiring different credentials to use
different OAM functions or capabilities within a specific OAM
function. Implementations may consider grouping users to different
security clearance levels and restricting functions and capabilities
to different clearance levels. However, Exact exact implementation details
of such a framework are outside the scope of this document.

15. IANA Considerations

IANA is requested to assign has made the following: assignments described below.

15.1. OAM Capabilitiy Capability Flags

Assign two

Two TRILL-VER sub-TLV Capability Flags (see Section 3.3) have been
assigned as follows:

Bit Description Reference
--- ----------- ---------

TBD[2]
2 OAM capable [this document]

TBD[3] Backwards compatible RFC 7455
3 Backwards-compatible OAM [this document] RFC 7455

15.2. CFM Code Points

IANA is requested to assign four Op-Codes

Four OpCodes have been assigned from the CFM "CFM OAM IETF
Op-Codes sub-registry OpCodes" sub-
registry as follows [suggested values in square
brackets]: follows:

Value Assignment Reference
===== ========== =========

TBD1[64]
----- ---------- ---------
64 Path Trace Reply [this document]
TBD2[65] RFC 7455
65 Path Trace Message [this document]
TBD3[66] Multicast RFC 7455
66 Multi-destination Tree Verification Reply
[this document]
TBD4[67] Multicast RFC 7455
67 Multi-destination Tree Verification Message
[this document]

IANA is requested to assign eleven RFC 7455

Eleven TLV Types have been assigned from the CFM "CFM OAM IETF TLV Types Types"
sub-registry as follows [suggested values in square
brackets]: follows:

Value Assignment Reference
===== ========== =========

TBDa[64]
----- ---------- ---------
64 TRILL OAM Application Identifier TLV
[this document]
TBDb[65] Out of Band RFC 7455
65 Out-of-Band Reply Address TLV [this document]
TBDc[66] RFC 7455
66 Diagnostic Label TLV [this document]
TBDd[67] RFC 7455
67 Original Data Payload TLV [this document]
TBDe[68] RFC 7455
68 RBridge Scope TLV [this document]
TBDf[69] RFC 7455
69 Previous RBridge nickname Nickname TLV
[this document]
TBDg[70] Next Hop RFC 7455
70 Next-Hop RBridge List TLV
[this document]
TBDh[71] RFC 7455
71 Multicast Receiver Port count Count TLV
[this document]
TBDi[72] RFC 7455
72 Flow Identifier TLV [this document]
TBDj[73] RFC 7455
73 Reflector Entropy TLV [this document]
TBDk[74] RFC 7455
74 Authentication TLV [this document] RFC 7455

15.3. MAC Addresses

IANA is requested to has assigned a unicast and a multicast MAC address under the
IANA OUI, Organizationally Unique Identifier (OUI) for identification of
OAM packets as discussed for the backward compatibility backwards-compatibility method
(Appendix A,
Section A.2) and based on the request template in Appendix C. The
assigned addresses are TBDmac1 [00-00-5E-90-01-00] 00-00-5E-90-01-00 (unicast) and
TBDmac2 [01-5E-90-01-00]
01-00-5E-90-01-00 (multicast).

15.4. Return codes Codes and sub codes Sub-codes

IANA is requested to create TRILL has created the "TRILL OAM Return Code Codes" registry within the TRILL Parameter Registry and, for each return code
"Transparent Interconnection of Lots of Links (TRILL) Parameters"
registry and a separate
sub code Sub-Registry as below: sub-code sub-registry for each Return Code as
shown below:

Registry: TRILL OAM Return Codes. Codes

Registration Procedure: Standards Action. Action

Return Code Assignment References
=========== ========== ==========
----------- ---------- ----------
0 Request message [this document] RFC 7455
1 Reply message [this document] RFC 7455
2-255 Unassigned [this document] RFC 7455

Sub-Registry: Sub Codes Sub-codes for TRILL OAM Return Code 0. 0

Registration Procedure: Standards Action.

Sub Code Action

Sub-code Assignment References
=========== ========== ==========
-------- ---------- ----------
0 Valid request [this document] RFC 7455
1-255 Unassigned [this document] RFC 7455

Sub-Registry: Sub Codes Sub-codes for TRILL OAM Return Code 1. 1

Registration Procedure: Standards Action.

Sub Code Action

Sub-code Assignment References
=========== ========== ==========
-------- ---------- ----------
0 Valid response [this document] RFC 7455
1 Fragment limit exceeded [this document] RFC 7455
2 Intermediate RBridge [this document] RFC 7455
3-255 Unassigned [this document] RFC 7455

15.5. TRILL RBridge Nickname Address Family

IANA has allocated 16396 as the Address Family Number for TRILL
RBridge nicknames.
nickname.

16. References

16.1. Normative References

[8021Q] IEEE, "IEEE Standard for Local and metropolitan area
networks -- Bridges and Bridged Networks", IEEE Std
802.1Q-2014, December 2014.

[IS-IS] ISO/IEC, "Information technology -- Telecommunications and
information exchange between systems -- Intermediate
System to Intermediate System intra-domain routeing
information exchange protocol for use in conjunction with
the protocol for providing the connectionless-mode network
service (ISO 8473)", ISO/IEC 10589:2002, Second Edition,
2002.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. 2008, <http://www.rfc-editor.org/info/rfc5226>.

[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Cryptographic Generic Cryptographic
Authentication", RFC 5310, February 2009. 2009,
<http://www.rfc-editor.org/info/rfc5310>.

[RFC6325] Perlman, R., et.al., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC 6325, July 2011. 2011,
<http://www.rfc-editor.org/info/rfc6325>.

[RFC7172] Eastlake 3rd, D., Zhang, M., Agarwal, P., Perlman, R., and
D. Dutt, "Transparent Interconnection of Lots of Links
(TRILL): Fine-Grained Labeling", RFC 7172, May
2014.

[8021Q] IEEE, "Media Access Control (MAC) Bridges and Virtual
Bridged Local Area Networks", IEEE Std 802.1Q-2011,
August, 2011.

[IS-IS] ISO/IEC 10589:2002, Second Edition, "Intermediate System
to Intermediate System Intra-Domain Routing Exchange
Protocol for use in Conjunction with the Protocol for
Providing the Connectionless-mode Network Service (ISO
8473)", 2002. 2014,
<http://www.rfc-editor.org/info/rfc7172>.

16.2. Informative References

[KARPISIS] Chunduri, U., Tian, A., and W. Lu, "KARP IS-IS security
analysis", Work in Progress, draft-ietf-karp-isis-
analysis-03, September 2014.

[RFC4379] Kompella, K. et.al, "Detecting Multi-Protocol Label
Switched (MPLS) Data Plane Failures", Eronen, P., Ed., and H. Tschofenig, Ed., "Pre-Shared Key
Ciphersuites for Transport Layer Security (TLS)", RFC 4379,
February 2006.
4279, December 2005,
<http://www.rfc-editor.org/info/rfc4279>.

[RFC6291] Andersson, L., et.al., van Helvoort, H., Bonica, R., Romascanu,
D., and S. Mansfield, "Guidelines for the use Use of the "OAM"
Acronym in the IETF" IETF", BCP 161, RFC 6291, June 2011. 2011,
<http://www.rfc-editor.org/info/rfc6291>.

[RFC6361] Carlson, J. and Eastlake, D. Eastlake 3rd, "PPP Transparent
Interconnection of Lots of Links (TRILL) Protocol Control
Protocol", RFC 6361, August 201. 2011,
<http://www.rfc-editor.org/info/rfc6361>.

[RFC6905] Senevirathne, T. et.al, T., Bond, D., Aldrin, S., Li, Y., and R.
Watve, "Requirements for Operations, Administration, and
Maintenance (OAM) in Transparent Interconnection of Lots
of Links (TRILL)", RFC 6905, March 2013. 2013,
<http://www.rfc-editor.org/info/rfc6905>.

[RFC7174] Salam, S., Senevirathne, T., Aldrin, S., and D. Eastlake
3rd, "Transparent Interconnection of Lots of Links (TRILL)
Operations, Administration, and Maintenance (OAM)
Framework", RFC 7174, May 2014,
<http://www.rfc-editor.org/info/rfc7174>.

[RFC7176] Eastlake, Eastlake 3rd, D., Senevirathne, T., Ghanwani, A., Dutt,
D., and A. Banerjee, "Transparent Interconnection of Lots
of Links (TRILL) Use of IS-IS", RFC 7176, May 2014,
<http://www.rfc-editor.org/info/rfc7176>.

[RFC7178] Eastlake 3rd, D., Manral, V., Li, Y., Aldrin, S., and D.
Ward, "Transparent Interconnection of Lots of Links
(TRILL): RBridge Channel Support", RFC 7178, May 2014,
<http://www.rfc-editor.org/info/rfc7178>.

[RFC7179] Eastlake 3rd, D., Ghanwani, A., Manral, V., Li, Y., and C.
Bestler, "Transparent Interconnection of Lots of Links
(TRILL): Header Extension", RFC 7179, May 2014,
<http://www.rfc-editor.org/info/rfc7179>.

[RFC7180] Eastlake 3rd, D., Senevirathne, T., Zhang, M., Ghanwani, A., Dutt, D., Manral, V., and
A. Banerjee, "Transparent Interconnection of Lots of Links (TRILL) Use of IS-IS", RFC 7176 May 2014.

[RFC7180] Eastlake, Donald, et.al. "TRILL:
(TRILL): Clarifications, Corrections, and Updates, Updates", RFC 7180
7180, May 2014.

[RFC7174] 2014, <http://www.rfc-editor.org/info/rfc7180>.

[RFC7456] Mizrahi, T., Senevirathne, T., Salam, S., Kumar, D., and
D. Eastlake 3rd, "Loss and Delay Measurement in
Transparent Interconnection of Lots of Links (TRILL)", RFC
7456, February 2015, <http://www.rfc-
editor.org/info/rfc7456>.

[TRILLOAMMIB]
Kumar, D., Salam, S., et.al., and T. Senevirathne, "TRILL OAM Framework", RFC 7174 ,
May 2014.

[RFC7179] Eastlake, Donald, et.al. "TRILL: Header Extension", RFC
7179, May 2014.
MIB", Work in Progress, draft-deepak-trill-oam-mib-01,
October 2013.

[Y1731] ITU-T Recommendation Y.1731, ITU-T, "OAM functions and mechanisms for Ethernet based
networks", ITU-T Recommendation G.8013/Y.1731, July November
2013.

[RFC7178] D. Eastlake, et.al. , "TRILL: RBridge Channel Support",
RFC 7178, May 2014.

[TRILLOAMMIB] Deepak Kumar et.al, "TRILL OAM MIB", draft-deepak-
trill-oam-mib, May 2013, work in progress.

[KARPISIS] U. Chunduri, et.a., "KARP IS-IS security analysis",
draft-karp-isis-analysis, September 2014, work in
progress.

Appendix A. Backwards Compatibility

Methodology

The methodology presented above in this document is in-line with the
[8021Q]
framework defined in [8021Q] for providing fault management coverage.
However, in practice, some TRILL platforms may not have the
capabilities to support some of the required techniques. In this
section,
appendix, we present a method that allows RBridges, which do not have
the required hardware capabilities, to participate in the TRILL OAM
solution.

There are two broad areas to be considered; 1. considered: 1) the Maintenance Point
(MEP/MIP) Model 2. Data plane and 2) data-plane encoding and frame identification

A.1 identification.

A.1. Maintenance Point (MEP/MIP) Model

For backwards compatibility, MEPs and MIPs are located in the CPU.
This will be referred to as the "central brain" model as opposed to
"port brain" model.

In the "central brain" model, an RBridge using either ACLs Access Control
Lists (ACLs) or some other method, method forwards qualifying OAM messages to
the CPU. The CPU then performs the required processing and
multiplexing to the correct MP (Maintenance Point).

Additionally, RBridges MUST have the capability to prevent the
leaking of OAM packets, as specified in [RFC6905].

A.2 Data plane encoding

A.2. Data-Plane Encoding and frame identification Frame Identification

The backwards compatibility backwards-compatibility method presented in this section defines
methods to identify OAM frames when implementations do not have
capabilities to utilize the TRILL OAM Alert flag presented earlier in
this document to identify OAM frames, frames in the hardware.

It is assumed that ECMP path selection of non-IP flows utilize utilizes MAC
DA, MAC SA SA, and VLAN, VLAN; IP Flows flows utilize IP DA, IP SA and SA, TCP/UDP port
numbers
numbers, and other Layer 3 and Layer 4 information. The well-known
fields to identify OAM flows are chosen such that they mimic the ECMP
selection of the actual data along the path. However, it is
important to note that, that there may be implementations that would
utilize these well-known fields for ECMP selections. Hence,
implementations that support OAM SHOULD move to utilizing the TRILL
Alert Flag, flag, as soon as possible possible, and methods presented here SHOULD be
used only as an interim solution.

Identification methods are divided in to 4 four broader groups:

1. Identification of Unicast non-IP OAM Flows,

2. Identification of Multicast non-IP OAM Flows,

3. Identification of Unicast IP OAM Flows Flows, and

4. Identification of Multicast IP OAM Flows Flows.

As presented in the table below, Figure 24, based on the flow type (as defined above),
implementations are required to use a well-known value in either the
Inner.MacSA field or OAM Ethertype field to identify OAM flows.

Receiving

A receiving RBridge identifies OAM flows based on the presence of the
well-known values in the specified fields, and additionally, fields. Additionally, for unicast
flows, the egress RBridge nickname of the packet MUST match that of
the local RBridge RBridge, or for multicast flows, the TRILL
header mutlicast Header multicast
("M") flag MUST be set.

Unicast OAM flows that qualify for local processing MUST be
redirected to the OAM process and MUST NOT be forwarded (that to (to prevent
leaking of the packet out of the TRILL campus).

A copy of Multicast multicast OAM flows that qualify for local processing MUST
be sent to the OAM process process, and packet the packets MUST be forwarded along
the normal path. Additionally, methods MUST be in place to prevent
multicast packets from leaking out of the TRILL campus.

The following table

Figure 24 summarizes the identification of different OAM frames from
data frames.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 22 24: Identification of TRILL OAM Frames
The unicast and multicast Inner.MacSAs used for the unicast and
multicast IP cases, respectively, are TBDmac1 [00-00-5E-90-01-00] 00-00-5E-90-01-00 and TBDmac2 [01-00-5E-90-01-01]
01-00-5E-90-01-00. These have been assigned by per the request in
Appendix C.

It is important to note that all RBridges MUST generate OAM flows
with the "A" flag set and CFM EtherType Ethertype "0x8902" at the flow entropy Flow Entropy
off-set. However, well-known values MUST be utilized as part of the
flow-entropy when generating OAM messages destined for older RBridges
that are compliant to the backwards compatibility backwards-compatibility method defined in
this appendix.

Appendix B. Base Mode for TRILL OAM

CFM, as defined in [8021Q], requires configuration of several
parameters before the protocol can be used. These parameters include
MAID, Maintenance Domain Level (MD-LEVEL) (MD-Level), and MEPIDs. MEP-IDs. The Base
Mode for TRILL OAM defined here facilitates ease of use and provides out of the box
out-of-the-box plug-and-play capabilities, supporting the Operational operational
and Manageability manageability considerations described in Section 6 of [RFC7174].

All RBridges that support TRILL OAM MUST support the Base Mode
operation.

All Rbridges RBridges MUST create a default MA with MAID as specified herein.

MAID [8021Q] has a flexible format and includes two parts:
Maintenance Domain Name and Short MA name. Name. In the Based Base Mode of
operation, the value of the Maintenance Domain Name must be the
character string "TrillBaseMode" (excluding the quotes "). quotes). In the Base
Mode operation operation, the Short MA Name format is set to a 2-octet integer
format (value 3 in Short MA Format field) and Short MA
name Name set to
65532 (0xFFFC).

The Default default MA belongs to MD-LEVEL MD-Level 3.

In the Base Mode of operation, each RBridge creates a single UP MEP
associated with a virtual OAM port with no physical layer (NULL PHY).
The MEPID MEP-ID associated with this MEP is the 2-octet RBridge Nickname. nickname.

By default, all RBridges operating in the Base Mode for TRILL OAM are
able to initiate LBM, PT PTM, and other OAM tools with no configuration.

Implementations MAY provide default flow-entropy to be included in
OAM messages. Content of the default flow-entropy is outside the
scope of this document.

Figure 23, below 25 depicts encoding of MAID within CCM messages.

+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Field Name |Size |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Maintenance | 1 |
|Domain Format | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Maintenance | 2 |
|Domain Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Maintenance | variable|
|Domain Name | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Short MA | 1 |
|Name Format | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Short MA | 2 |
|Name Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Short MA | variable|
|Name | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Padding | Variable|
+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 23 25: MAID structure Structure as defined Defined in [8021Q]

Maintenance Domain Name Format is Format: set to Value: value 4

Maintenance Domain Name Length is Length: set to value: value 13

Maintenance Domain Name is Name: set to: to TrillBaseMode

Short MA Name Format is Format: set to value: value 3

Short MA Name Length is Length: set to value: value 2

Short MA Name is Name: set to: to FFFC

Padding: set of zero up to 48 octets of total length of the MAID. MAID

Please refer to [8021Q] for details.

Appendix C. MAC Addresses Request

Applicant Name: IETF TRILL Working Group

Applicant Email: tsenevir@cisco.com

Applicant Telephone: +1-408-853-2291

Use Name: TRILL OAM

Document: draft-tissa-trill-oam-fm RFC 7455

Specify whether this is an application for EUI-48 or EUI-64
identifiers: EUI-48

Size of Block requested: 1

Specify multicast, unicast, or both: Both

17.

Acknowledgments

Work in on this document was largely inspired by the directions provided
by Stewart Bryant in finding a common OAM solution between SDOs.

Acknowledgments are due for many who volunteered to review this
document, notably, Jari Arkko, Adrian Farrel, Pete Resnick, Stephen
Farrell, Dan Romascanu, Gayle Nobel Nobel, and Tal Mizrahi.

Special appreciations are appreciation is due for to Dinesh Dutt for his support and
encouragement, especially during the initial discussion phase of
TRILL OAM.

This document was prepared using 2-Word-v2.0.template.dot.

Authors' Addresses

Tissa Senevirathne
CISCO
Cisco Systems
375 East Tasman Drive. Drive
San Jose, CA 95134
USA.
United States

Phone: +1 408-853-2291
Email:
EMail: tsenevir@cisco.com

Norman Finn
CISCO
Cisco Systems
510 McCarthy Blvd
Milpitas, CA 95035
USA

Email:
United States

EMail: nfinn@cisco.com

Samer Salam
CISCO
Cisco Systems
595 Burrard St. St., Suite 2123
Vancouver, BC V7X 1J1, 1J1
Canada

Email:

EMail: ssalam@cisco.com
Deepak Kumar
CISCO
Cisco Systems
510 McCarthy Blvd, Blvd
Milpitas, CA 95035, USA

Phone : 95035
United States

Phone: +1 408-853-9760
Email:
EMail: dekumar@cisco.com

Donald Eastlake 3rd
Huawei Technologies
155 Beaver Street
Milford, MA 01757
United States

Phone: +1-508-333-2270
Email:
EMail: d3e3e3@gmail.com

Sam Aldrin
Huawei Technologies
2330 Central Express Way
Santa Clara, CA 95951
USA

Email:
United States

EMail: aldrin.ietf@gmail.com

Yizhou Li
Huawei Technologies
101 Software Avenue, Avenue
Nanjing 210012
China

Phone: +86-25-56625375
Email:
EMail: liyizhou@huawei.com