Internet Engineering Task Force (IETF) W. Hao
Request for Comments: 8383 D. Eastlake, 3rd
Category: Standards Track Y. Li
ISSN: 2070-1721 Huawei
M. Umair
Cisco
May 2018
Transparent Interconnection of Lots of Links (TRILL):
Address Flush Message
Abstract
The TRILL (Transparent Interconnection of Lots of Links) protocol, by
default, learns end station addresses from observing the data plane.
In particular, it learns local Media Access Control (MAC) addresses
and the edge switch port of attachment from the receipt of local data
frames and learns remote MAC addresses and the edge switch port of
attachment from the decapsulation of remotely sourced TRILL Data
packets.
This document specifies a message by which a TRILL switch can
explicitly request other TRILL switches to flush certain MAC
reachability learned through the decapsulation of TRILL Data packets.
This is a supplement to the TRILL automatic address forgetting (see
Section 4.8.3 of [RFC6325]) and can assist in achieving more rapid
convergence in case of topology or configuration change.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8383.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology and Abbreviations . . . . . . . . . . . . . . 3
2. Address Flush Message Details . . . . . . . . . . . . . . . . 4
2.1. VLAN Block Only Case . . . . . . . . . . . . . . . . . . 5
2.2. Extensible Case . . . . . . . . . . . . . . . . . . . . . 7
2.2.1. Blocks of VLANs . . . . . . . . . . . . . . . . . . . 11
2.2.2. Bit Map of VLANs . . . . . . . . . . . . . . . . . . 12
2.2.3. Blocks of FGLs . . . . . . . . . . . . . . . . . . . 12
2.2.4. list of FGLs . . . . . . . . . . . . . . . . . . . . 13
2.2.5. Big Map of FGLs . . . . . . . . . . . . . . . . . . . 14
2.2.6. All Data Labels . . . . . . . . . . . . . . . . . . . 14
2.2.7. MAC Address List . . . . . . . . . . . . . . . . . . 14
2.2.8. MAC Address Blocks . . . . . . . . . . . . . . . . . 15
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
3.1. Address Flush RBridge Channel Protocol Number . . . . . . 16
3.2. TRILL Address Flush TLV Types . . . . . . . . . . . . . . 17
4. Security Considerations . . . . . . . . . . . . . . . . . . . 17
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1. Normative References . . . . . . . . . . . . . . . . . . 17
5.2. Informative References . . . . . . . . . . . . . . . . . 18
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
By default, edge TRILL (Transparent Interconnection of Lots of Links)
switches [RFC6325] [RFC7780], also called edge Routing Bridges
(RBridges), learn end station MAC address reachability from observing
the data plane. On receipt of a native frame from an end station,
they would learn the local MAC address attachment of the source end
station. And on egressing (decapsulating) a remotely originated
TRILL Data packet, they learn the remote MAC address and remote
attachment TRILL switch. Such learning is all scoped by data label
(VLAN or Fine-Grained Label (FGL) [RFC7172]).
TRILL has mechanisms for timing out such learning and appropriately
clearing it based on some network connectivity and configuration
changes; however, there are circumstances under which it would be
helpful for a TRILL switch to be able to explicitly flush (purge)
certain learned end station reachability information in remote
RBridges to achieve more-rapid convergence. Section 6.2 of [RFC4762]
is an example of the use of such a mechanism.
Another example, based on Appendix A.3 of [RFC6325] ("Wiring Closet
Topology"), presents a bridged LAN connected to a TRILL network via
multiple RBridge ports. For optimum paths, Appendix A.3.3 suggests
configuring the RBridge ports to be like one Spanning Tree Protocol
(STP) tree root in the bridged LAN. The Address Flush message in
this document could also be triggered in this case when one of the
edge RBridges receives Topology Change (TC) information (e.g., TC in
STP, Topology Change Notification (TCN) in Multiple Spanning Tree
Protocol (MSTP) (MSTP)) in order to rapidly flush the MAC addresses for
specific VLANs learned at the other edge RBridge ports.
A TRILL switch can easily flush any locally learned addresses it
wants. This document specifies an RBridge Channel Support protocol
[RFC7178] message to request flushing address information for
specific VLANs or FGLs ([RFC7172]) learned from decapsulating TRILL
Data packets.
1.1. Terminology and Abbreviations
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 [RFC2119] [RFC8174]
when, and only when, they appear in all capitals, as shown here.
This document uses the terms and abbreviations defined in [RFC6325]
and [RFC7978] [RFC7178] as well as the following:
Data Label: A VLAN or FGL
Edge TRILL Switch: A TRILL switch attached to one or more links that
provide end station service
FCS: Frame Check Sequence
FGL: Fine-Grained Label [RFC7172]
Management VLAN: A VLAN in which all TRILL switches in a campus
indicate interest so that multi-destination TRILL Data packets,
including RBridge Channel protocol messages [RFC7978], [RFC7178], sent with
that VLAN as the Inner.VLAN will be delivered to all TRILL
switches in the campus. Usually, no end station service is
offered in the Management VLAN.
MAC: Media Access Control
RBridge: An alternative name for a TRILL switch
STP: Spanning Tree Protocol
TC: Topology Change message
TCN: Topology Change Notification message
TRILL switch: A device implementing the TRILL protocol RFC 6235 [RFC6325]
[RFC7780]
2. Address Flush Message Details
The Address Flush message is an RBridge Channel protocol message
[RFC7178].
The general structure of an RBridge Channel packet on a link between
TRILL switches is shown in Figure 1. The Protocol field in the
RBridge Channel Header gives the type of RBridge Channel packet and
indicates how to interpret the Channel-Protocol-Specific Payload
[RFC7178].
+-----------------------------------+
| Link Header |
+-----------------------------------+
| TRILL Header |
+-----------------------------------+
| Inner Ethernet Addresses |
+-----------------------------------+
| Data Label (VLAN or FGL) |
+-----------------------------------+
| RBridge Channel Header |
+-----------------------------------+
| Channel-Protocol-Specific Payload |
+-----------------------------------+
| Link Trailer (FCS if Ethernet) |
+-----------------------------------+
Figure 1: RBridge Channel Protocol Message Structure
By default, an Address Flush RBridge Channel protocol message applies
to addresses within the Data Label that appear right after the Inner
Ethernet Addresses. Address Flush protocol messages are usually sent
as multi-destination packets (TRILL Header M bit equal to one) so as
to reach all TRILL switches offering end station service in the VLAN
or FGL specified by that Data Label. Both multi-destination and
unicast Address Flush messages SHOULD be sent at priority 6 since
they are important control messages but are lower priority than
control messages that establish or maintain adjacency.
Nevertheless:
- There are provisions for optionally indicating the Data Label(s)
to be flushed for cases where the Address Flush message is sent
over a Management VLAN or the like.
- An Address Flush message can be sent unicast, if it is desired to
clear addresses at one TRILL switch only.
- An Address Flush message can be sent selectively to the RBridges
that have at least one access port configured as one of the VLANs
or FGLs specified in the Address Flush message payload.
Implementations should consider logging Address Flush messages
received with appropriate protections against packet storms.
2.1. VLAN Block Only Case
Figure 2 expands the RBridge Channel Header and Channel-Protocol-
Specific Payload from Figure 1 for the case of the VLAN-only-based
Address Flush message. This form of the Address Flush message is
optimized for flushing MAC addresses based on nickname and blocks of
VLANs. 0x8946 is the Ethertype assigned by IEEE for the RBridge
Channel protocol. protocol [RFC7178].
0 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
RBridge Channel Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | 0x0 |Channel Protocol= 0x009|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address Flush Protocol Specific:
+-+-+-+-+-+-+-+-+
| K-nicks |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nickname 1 | Nickname 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nickname ... | Nickname K-nicks |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| K-VLBs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN 1 | RESV | End.VLAN 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN 2 | RESV | End.VLAN 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN ... | RESV | End.VLAN ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN K-VLBs | RESV | End.VLAN K-VLBs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Address Flush Message - VLAN Block Case
The fields in Figure 2 related to the Address Flush message are as
follows:
Channel Protocol: The RBridge Channel Protocol value allocated for
Address Flush (see Section 3).
K-nicks: The number of nicknames listed as an unsigned integer. If
this is zero, the ingress nickname in the TRILL Header [RFC6325]
is considered to be the only nickname to which the message
applies. If non-zero, it gives the number of nicknames listed
right after K-nicks to which the message applies, and, in this
non-zero case, the flush does not apply to the ingress nickname in
the TRILL Header unless it is also listed. The message flushes
address learning due to egressing TRILL Data packets that had an
ingress nickname to which the message applies.
Nickname: A listed nickname to which it is intended that the Address
Flush message apply. If an unknown or reserved nickname occurs in
the list, it is ignored, but the address flush operation is still
executed with the other nicknames. If an incorrect nickname
occurs in the list, so that some address learning is flushed that
should not have been flushed, the network will still operate
correctly; however, it will be less efficient as the incorrectly
flushed learning is relearned.
K-VLBs: The number of VLAN blocks present as an unsigned integer.
If this byte is zero, the message is the more general format
specified in Section 2.2. If it is non-zero, it gives the number
of blocks of VLANs present. Thus, in the VLAN Block address flush
case, K-VLBs will be at least one.
RESV: 4 reserved bits. MUST be sent as zero and ignored on receipt.
Start.VLAN, End.VLAN: These 12-bit fields give the beginning and
ending VLAN IDs of a block of VLANs. The block includes both the
starting and ending values; so, a block of size one is indicated
by setting End.VLAN equal to Start.VLAN. If Start.VLAN is 0x000,
it is treated as if it was 0x001. If End.VLAN is 0xFFF, it is
treated as if it was 0xFFE. If End.VLAN is smaller than
Start.VLAN, considering both as unsigned integers, that VLAN block
is ignored, but the address flush operation is still executed with
other VLAN blocks in the message. VLAN blocks may overlap, in
which case, the address flush operation is applicable to a VLAN
covered by any one or more of the blocks in the message.
This message flushes all addresses in an applicable VLAN learned from
egressing TRILL Data packets with an applicable nickname as ingress.
To flush addresses for all VLANs, it is easy to specify a block
covering all valid VLAN IDs (i.e., from 0x001 to 0xFFE).
2.2. Extensible Case
A more general form of the Address Flush message is provided to
support flushing by FGL and more efficient encodings of VLANs and
FGLs where using a set of contiguous blocks is cumbersome. It also
supports optionally specifying the MAC addresses to clear. This form
is extensible.
The extensible case is indicated by a zero in the byte shown in
Figure 2 as "K-VLBs" followed by other information encoded as TLVs.
0 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
RBridge Channel Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | 0x0 |Channel Protocol=0x009 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address Flush Protocol Specific:
+-+-+-+-+-+-+-+-+
| K-nicks |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nickname 1 | Nickname 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nickname ... | Nickname K-nicks |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | TLVs ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...
Figure 3: Address Flush Message - Extensible Case
Channel Protocol, K-nicks, Nickname: These fields are as specified
in Section 2.1.
TLVs: If the byte immediately before the TLVs field, which is the
byte labeled "K-VLBs" in Figure 2, is zero, as shown in Figure 3,
the remainder of the message consists of TLVs encoded as shown in
Figure 4.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 4: Type, Length, Value
Type: The 8-bit TLV type as shown in the table below. See
subsections of Section 2.2 for details on each type assigned
below. If the type is reserved or not known by a receiving
RBridge, that receiving RBridge ignores the value and skips to the
next TLV by use of the Length byte. There is no provision for a
list of VLAN ID TLVs as there are few enough of them that an
arbitrary subset of VLAN IDs can be represented as a bit map.
Type Description Reference
------ ------------------ -----------------
0 Reserved [RFC8383]
1 Blocks of VLANs [RFC8383]
2 Bit Map of VLANs [RFC8383]
3 Blocks of FGLs [RFC8383]
4 List of FGLs [RFC8383]
5 Bit Map of FGLs [RFC8383]
6 All Data Labels [RFC8383]
7 MAC Address List [RFC8383]
8 MAC Address Blocks [RFC8383]
9-254 Unassigned
255 Reserved [RFC8383]
Length: The 8-bit unsigned integer length in bytes of the remaining
information in the TLV after the Length byte. The Length MUST NOT
imply that the value extends beyond the end of the RBridge
Channel-Protocol-Specific Payload area. If it does, the Address
Flush message is corrupt and MUST be ignored.
Value: Depends on the TLV type.
In an extensible Address Flush message, when the TLVs are parsed,
those TLVs having unknown types are ignored by the receiving RBridge.
There may be multiple instances of TLVs with the same Type in the
same Address Flush message, and TLVs are not required to be in any
particular order.
- All RBridges implementing the Address Flush RBridge Channel
protocol message MUST implement types 1 and 2, the VLAN types, and
Type 6, which indicates addresses are to be flushed for all Data
Labels.
- RBridges that implement the Address Flush message and implement
FGL ingress/egress MUST implement types 3, 4, and 5, the FGL
types. (An RBridge that is merely FGL safe [RFC7172], but cannot
egress FGL TRILL Data packets, SHOULD ignore the FGL types, as it
will not learn any FGL-scoped MAC addresses from the data plane.)
- RBridges that implement the Address Flush message SHOULD implement
types 7 and 8 so that specific MAC addresses can be flushed. If
they do not, the effect will be to flush all MAC addresses for the
indicated Data Labels, which may be inefficient as any MAC
addresses not intended to be flushed will have to be relearned.
The parsing of the TLVs by a receiving RBridge results in three
pieces of information:
1. a flag indicating whether one or more Type 6 TLVs (All Data
Labels) were encountered;
2. a set of Data Labels accumulated from VLAN and/or FGL
specifying TLVs in the message; and,
3. if the MAC address TLV types are implemented, a set of MAC
addresses accumulated from MAC-address-specifying TLVs in the
message.
VLANs/FGLs might be indicated more than once due to overlapping
blocks or the like, and a VLAN/FGL is included in the above set of
VLANs/FGLs if it occurs in any TLV in the Address Flush message. A
MAC address might be indicated more than once due to overlapping
blocks or the like, and a particular MAC address is included in the
above set of MAC addresses if it occurs in any TLV in the Address
Flush message.
After the above information has been accumulated by parsing the TLVs,
three sets are derived as described below: a set of nicknames, a set
of Data Labels, and a set of MAC addresses. The address flush
operation at the receiver applies to the cross product of these
derived sets. That is, a { Data Label, MAC address, nickname }
triple is flushed if and only if the Data Label matches an element in
the derived set of Data Labels, the MAC address matches an element in
the derived set of MAC address, and the nickname matches an element
in the derived set of nicknames. In the case of Data Labels and MAC
addresses, a special value of the set, {ALL}, is permitted, which
matches all values.
The sets are derived as follows:
Data Labels set:
If the Type 6 TLV has been encountered, the set is {ALL}, else,
if any Data Labels have been accumulated by processing Data
Label TLVs (Types 1, 2, 3, 4, and 5), the set is those
accumulated Data Labels, else,
the Data Labels set is null and the Address Flush message does
nothing.
MAC Addresses set:
In the receiver does not implement the MAC address types (Types
7 and 8) or it does implement those types but no MAC
addresses are accumulated in parsing the TLVs, then the MAC
Address set is {ALL},
else, the MAC Addresses set is the set of MAC addresses
accumulated in processing the TLVs.
Nicknames set:
If the K-nicks field in the Address Flush message was zero,
then the ingress nickname in the TRILL Header of the message
is the sole nickname set member, else,
the nicknames set members are the K-nicks nicknames listed in
the Address Flush message.
The various formats below are provided for encoding efficiency. A
block of values is most efficient when there are a number of
consecutive values. A bit map is most efficient if there are
scattered values within a limited range. And a list of single values
is most efficient if there are widely scattered values.
2.2.1. Blocks of VLANs
If the TLV Type is 1, the value is a list of blocks of VLANs as
follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 1 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN 1 | RESV | End.VLAN 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN 2 | RESV | End.VLAN 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN ... | RESV | End.VLAN ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The meaning of Start.VLAN and End.VLAN is as specified in
Section 2.1. Length MUST be a multiple of 4. If Length is not a
multiple of 4, the TLV is corrupt and the Address Flush message MUST
be discarded.
2.2.2. Bit Map of VLANs
If the TLV Type is 2, the value is a bit map of VLANs as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| RESV | Start.VLAN | Bits...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
The value portion of the TLV begins with two bytes having the 12-bit
starting VLAN ID right justified (the top 4 bits are as specified in
Section 2.1 RESV). This is followed by bytes with one bit per VLAN
ID. The high order bit of the first byte is for VLAN N. The next-
to-the-highest order bit is for VLAN N+1. The low order bit of the
first byte is for VLAN N+7. The high order bit of the second byte,
if there is a second byte, is for VLAN N+8, and so on. If that bit
is a one, the Address Flush message applies to that VLAN. If that
bit is a zero, then addresses that have been learned in that VLAN are
not flushed. Note that Length MUST be at least 2. If Length is 0 or
1, the TLV is corrupt and the Address Flush message MUST be
discarded. VLAN IDs do not wrap around. If there are enough bytes
so that some bits correspond to VLAN ID 0xFFF or higher, those bits
are ignored, but the message is still processed for bits
corresponding to valid VLAN IDs.
2.2.3. Blocks of FGLs
If the TLV Type is 3, the value is a list of blocks of FGLs as
follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 3 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Start.FGL 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| End.FGL 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Start.FGL 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| End.FGL 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Start.FGL ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| End.FGL ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The TLV value consists of sets of Start.FGL and End.FGL numbers. The
Address Flush information applies to the FGLs in that range,
inclusive. A single FGL is indicated by setting both Start.FGL and
End.FGL to the same value. If End.FGL is less than Start.FGL,
considering them as unsigned integers, that block is ignored, but the
Address Flush message is still processed for any other blocks
present. For this Type, Length MUST be a multiple of 6; if it is
not, the TLV is corrupt and the Address Flush message MUST be
discarded if the receiving RBridge implements Type 3.
2.2.4. list of FGLs
If the TLV Type is 4, the value is a list of FGLs as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 4 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FGL 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FGL 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FGL ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The TLV value consists of FGL numbers each in 3 bytes. The Address
Flush message applies to those FGLs. For this Type, Length MUST be a
multiple of 3; if it is not, the TLV is corrupt and the Address Flush
message MUST be discarded if the receiving RBridge implements Type 4.
2.2.5. Big Map of FGLs
If the TLV Type is 5, the value is a bit map of FGLs as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 5 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Start.FGL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bits...
+-+-+-+-+-+-+-+-
The TLV value consists of three bytes with the 24-bit starting FGL
value N. This is followed by bytes with one bit per FGL. The high
order bit of the first byte is for FGL N. The next-to-the-highest
order bit is for FGL N+1. The low order bit of the first byte is for
FGL N+7. The high order bit of the second byte, if there is a second
byte, is for FGL N+8, and so on. If that bit is a one, the Address
Flush message applies to that FGL. If that bit is a zero, then
addresses that have been learned in that FGL are not flushed. Note
that Length MUST be at least 3. If Length is 0, 1, or 2 for a Type 5
TLV, the TLV is corrupt and the Address Flush message MUST be
discarded if Type 5 is implemented. FGLs do not wrap around. If
there are enough bytes so that some bits correspond to an FGL higher
than 0xFFFFFF, those bits are ignored, but the message is still
processed for bits corresponding to valid FGLs.
2.2.6. All Data Labels
If the TLV Type is 6, the value is null as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 6 | Length = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This type is used when an RBridge wants to withdraw all addresses for
all the Data Labels (all VLANs and FGLs). Length MUST be zero. If
Length is any other value, the TLV is corrupt and the Address Flush
message MUST be discarded.
2.2.7. MAC Address List
If the TLV Type is 7, the value is a list of MAC addresses as
follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 7 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC 1 upper half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC 1 lower half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC 2 upper half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC 2 lower half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC ... upper half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC ... lower half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The TLV value consists of a list of 48-bit MAC addresses. Length
MUST be a multiple of 6. If it is not, the TLV is corrupt, and the
Address Flush message MUST be discarded if the receiving RBridge
implements Type 7.
2.2.8. MAC Address Blocks
If the TLV Type is 8, the value is a list of blocks of MAC addresses
as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 8 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.start 1 upper half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.start 1 lower half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.end 1 upper half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.end 1 lower half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.start 2 upper half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.start 2 lower half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.end 2 upper half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.end 2 lower half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.start ... upper half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.start ... lower half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.end ... upper half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC.end ... lower half |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The TLV value consists of sets of Start.MAC and End.MAC numbers. The
Address Flush information applies to the 48-bit MAC Addresses in that
range, inclusive. A single MAC address is indicated by setting both
Start.MAC and End.MAC to the same value. If End.MAC is less than
Start.MAC, considering them as unsigned integers, that block is
ignored but the Address Flush message is still processed for any
other blocks present. For this Type, Length MUST be a multiple of
12; if it is not, the TLV is corrupt and the Address Flush message
MUST be discarded if the receiving RBridge implements Type 7.
3. IANA Considerations
3.1. Address Flush RBridge Channel Protocol Number
IANA has assigned 0x009 as the Address Flush RBridge Channel Protocol
number from the range of RBridge Channel protocols allocated by
Standards Action [RFC7178] [RFC8126].
The added entry to the "RBridge Channel Protocols" registry at
<https://www.iana.org/assignments/trill-parameters/> is as follows:
Protocol Description Reference
-------- -------------- ------------------
0x009 Address Flush [RFC8383]
3.2. TRILL Address Flush TLV Types
IANA has created the "TRILL Address Flush TLV Types" registry at
<https://www.iana.org/assignments/trill-parameters/> as a subregistry
of the "RBridge Channel Protocols" registry. Registry headers are as
below. The initial entries are as in the table in Section 2.2.
Registry: TRILL Address Flush TLV Types
Registration Procedures: IETF Review
Reference: [RFC8383]
4. Security Considerations
The Address Flush RBridge Channel Protocol itself provides no
security assurances or features. However, Address Flush protocol
messages can be secured by use of the RBridge Channel Header
Extension [RFC7978]. It is RECOMMENDED that all RBridges that
implement the Address Flush message be configured to ignore such
messages unless they have been secured with an RBridge Channel Header
Extension that meets local security policy.
If RBridges receiving Address Flush messages do not require them to
be at least authenticated, they are relatively easy to forge. In
that case, such forged Address Flush messages can reduce network
efficiency, by purging useful learned information that will have to
be relearned. This provides a denial-of-service attack, but cannot
cause incorrect operation in the sense that it cannot cause a frame
to be improperly delivered.
See [RFC7178] for general RBridge Channel Security Considerations.
See [RFC6325] for general TRILL Security Considerations.
5. References
5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6325] Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC 6325, DOI 10.17487/RFC6325, July 2011,
<https://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,
DOI 10.17487/RFC7172, May 2014,
<https://www.rfc-editor.org/info/rfc7172>.
[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,
DOI 10.17487/RFC7178, May 2014,
<https://www.rfc-editor.org/info/rfc7178>.
[RFC7780] Eastlake 3rd, D., Zhang, M., Perlman, R., Banerjee, A.,
Ghanwani, A., and S. Gupta, "Transparent Interconnection
of Lots of Links (TRILL): Clarifications, Corrections, and
Updates", RFC 7780, DOI 10.17487/RFC7780, February 2016,
<https://www.rfc-editor.org/info/rfc7780>.
[RFC7978] Eastlake 3rd, D., Umair, M., and Y. Li, "Transparent
Interconnection of Lots of Links (TRILL): RBridge Channel
Header Extension", RFC 7978, DOI 10.17487/RFC7978,
September 2016, <https://www.rfc-editor.org/info/rfc7978>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
5.2. Informative References
[RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
<https://www.rfc-editor.org/info/rfc4762>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
Acknowledgements
The following are thanked for their contributions:
Ramkumar Parameswaran, Henning Rogge
Authors' Addresses
Weiguo Hao
Huawei Technologies
101 Software Avenue,
Nanjing 210012
China
Phone: +86-25-56623144
Email: haoweiguo@huawei.com
Donald Easlake 3rd
Huawei Technologies
155 Beaver Street
Milford, MA 01757
United States of America
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
Yizhou Li
Huawei Technologies
101 Software Avenue,
Nanjing 210012
China
Phone: +86-25-56624629
Email: liyizhou@huawei.com
Mohammed Umair
Cisco
Cessna Business Park, Kadubeesanahalli Village, Hobli,
Sarjapur, Varthur Main Road, Marathahalli,
Bengaluru, Karnataka 560087
India
Email: mohammed.umair2@gmail.com