wdiff rfc8397.original rfc8397.txt

TRILL Working Group
Internet Engineering Task Force (IETF) M. Zhang
Internet Draft
Request for Comments: 8397 D. Eastlake 3rd
Intended
Category: Proposed Standard Standards Track Huawei
ISSN: 2070-1721 R. Perlman
Dell EMC
H. Zhai
JIT
D. Liu
China Telcom Telecom Co., Ltd
Expires: September 15, 2018 March 14,
May 2018

TRILL

Transparent Interconnection of Lots of Links (TRILL) Multilevel
Using Unique Nicknames
draft-ietf-trill-multilevel-unique-nickname-07.txt

Abstract

TRILL (Transparent Interconnection of Lots of Links) routing can be
extended to support multiple levels by building on the multilevel
feature of IS-IS routing. Depending on how nicknames are managed,
there are two primary alternatives to realize TRILL multilevel: the
unique nickname approach and the aggregated nickname approach as
discussed in RFC 8243. This document specifies a unique nickname
approach. This approach gives unique nicknames to all TRILL switches
across the multilevel TRILL campus.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 ....................................................3
2. Acronyms and Terminology . . . . . . . . . . . . . . . . . . . 3 ........................................4
3. Data Routing . . . . . . . . . . . . . . . . . . . . . . . . . 4 ....................................................4
3.1. Unicast Routing . . . . . . . . . . . . . . . . . . . . . . 4 ............................................4
3.2. Multi-destination Routing . . . . . . . . . . . . . . . . . 5 ..................................5
3.2.1. Local Distribution Trees . . . . . . . . . . . . . . . 5 ............................6
3.2.2. Global Distribution Trees . . . . . . . . . . . . . . . 5 ...........................6
4. Protocol Basics and Extensions . . . . . . . . . . . . . . . . 8 ..................................8
4.1. Multilevel TRILL Basics . . . . . . . . . . . . . . . . . . 8 ....................................8
4.2. Nickname Allocation . . . . . . . . . . . . . . . . . . . . 8 ........................................9
4.3. Nickname Announcements . . . . . . . . . . . . . . . . . . 9 .....................................9
4.4. Capability Indication . . . . . . . . . . . . . . . . . . . 11 .....................................11
5. Mix with Aggregated nickname Nickname Areas . . . . . . . . . . . . . . 11 .............................11
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 12 ........................................12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 12 ............................................13
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 .....................................................13
8.1. Normative References . . . . . . . . . . . . . . . . . . . 13 ......................................13
8.2. Informative References . . . . . . . . . . . . . . . . . . 14
9. ....................................14
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 14
Author's ......................................................15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 ................................................15

1. Introduction

The multiple level multiple-level feature of [IS-IS] can increase the scalability of
TRILL as discussed in [RFC8243]. However, multilevel IS-IS needs
some extensions to support the TRILL multilevel feature. The two
most significant extensions are how TRILL switch nicknames are
managed and how distribution trees are handled [RFC8243].

There are two primary alternatives to realize TRILL multilevel
[RFC8243]. One approach, which is referred to as the "aggregated
nickname" approach, involves assigning nicknames to the areas, and
allowing nicknames to be reused in different areas, areas by having the
border TRILL switches rewrite nickname fields when entering or
leaving an area. For more description of the aggregated nickname
approach, one can refer to [RFC8243] and [SingleN]. The other
approach, which is referred to as the "unique nickname" approach, is
specified in this document. The unique nickname approach gives
unique nicknames to all the TRILL switches in the multilevel campus, campus
by having the Level-1/Level-2 border TRILL switches at the Level 1 / Level 2 border
advertise into the Level 1 area which those nicknames are not available for
assignment in the
area, that area and insert advertising into the Level 2 area which those
nicknames that are used by this the Level 1 area so that other areas
cannot use them anymore, as well as
informing anymore. The advertising of Level 1 nicknames
informs the rest of the campus how to reach the nicknames residing in this
that area. In the this document, protocol extensions that support such
advertisement are specified.

Each RBridge in a unique nickname area calculates two types of trees:
local distribution trees and global distributions trees. For multi-
destination traffic that is limited to an area, the packets will be
flooded on a local distribution tree. Otherwise, the multi-
destination packets will be flooded along a global distribution tree.

In the unique nickname approach, nicknames are globally valid so that
border RBridges do not rewrite the nickname field of TRILL data
packets that transition between Level 1 and Level 2, as border
RBridges do in the aggregated nickname approach. If a border RBridge
is a transit node on a forwarding path, it does not learn MAC
addresses of the TRILL data packets forwarded along this path.
Testing and maintenance operations that originate in one area and
terminate in a different area are also simplified [RFC8243]. For
these reasons, the unique nickname approach might realize simpler
border RBridges than the aggregated nickname approach. However, the
unique nickname approach is less scalable and may be less well suited
for very large campuses.

2. Acronyms and Terminology

Border RBridge: An RBridge that is located on the border between two
or more RBridge areas.

Data Label: VLAN or FGL [RFC7172]

IS-IS: Intermediate System to Intermediate System [IS-IS]

RBridge: A device implementing the TRILL protocol.

TRILL: TRansparent Transparent Interconnection of Lots of Links or Tunneled
Routing in the Link Layer [RFC6325].

TRILL switch: An alternative name for an RBridge.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

3. Data Routing

Area X level 2 Area Y
+-----------------+ +---------------------+ +------------+
| | | | | |
S---RB27---Rx--Rz---RB2---Rb---Rc--Rd---Re--RB3---Rk--RB44---D
| 27 | | | | 44 |
| | | | | |
+-----------------+ +---------------------+ +------------+

Figure 3.1: 1: An example topology Example Topology for TRILL multilevel Multilevel

Figure 3.1 1 is adapted from the example topology of [RFC8243]. [RFC8243], where S
is Source, and D is Destination.

The routing processes are described in the following two subsections.

3.1. Unicast Routing

The plain RBridge RB27 has a different view of the topology of the
TRILL campus than its border RBridge RB2. For an outward path that
reaches an RBridge not in the same area (say (say, RB44), RB27 calculates
the segment of the path in Area X, the border RBridge RB2 calculates
the segment in Level 2, while the border RBridge to the destination
area, RBridge RB3, calculates the segment from itself to RB44.

Let us say that S transmits a frame to destination D and let us say
that D's location is learned by the relevant TRILL switches already.
These relevant switches have learned the following:

1) RB27 has learned that D is connected to nickname 44.
2) RB2 has learned that nickname 44 is accessible through RB3.

The following sequence of events will occur:

- S transmits an Ethernet frame with source MAC = S and destination
MAC = D.

- RB27 encapsulates with a TRILL header with ingress RBridge
nickname 27, and egress RBridge nickname 44 producing a TRILL Data
packet.

- RB2 has announced in the Level 1 IS-IS instance in Area X, X that it
owns all nicknames of other areas, including 44. Therefore, IS-IS
routes the packet to RB2.

- The packet is forwarded through Level 2, from RB2 to RB3, which
has advertised, in Level 2, it owns the nickname 44.

- RB3, when forwarding into Area Y, does not change the ingress
nickname 27 or the egress nickname 44.

- RB44, when decapsulating, learns that S is attached to nickname
27.

3.2. Multi-destination Routing

The scope of Multi-destination routing is defined by the tree root
nickname. A tree with a Level 2 tree root nickname is global global, and a
tree with a Level 1 tree root nickname is local. See Section 4.2 for
the Level 1 and Level 2 nickname allocation.

Border RBridges announce the global trees to be calculated only for
those Data Labels that span across areas. APPsub-TLVs as specified
in Section 3.2 of [RFC7968] will be advertised for this purpose.
Based on the Data Label, an ingress RBridge can determine whether a
global tree or a local tree is to be used for a TRILL multi-destination multi-
destination Data packet.

If there are legacy TRILL switches that do not understand the APPsub-
TLVs for tree selection, configuration MUST guarantee that Data
Labels [RFC7172] being used globally in Level 2 are disabled on these
legacy TRILL switches switches. (Otherwise, the legacy TRILL switches might
use local trees for multi-destination traffic with a global scope.). scope.)
These legacy TRILL switches may use global trees to flood multi-
destination packets with a scope of the local area. Those global
trees MUST be pruned at the border TRILL switches based on Data
Labels.

3.2.1. Local Distribution Trees

The root RBridge RB1 of a local distribution tree resides in the
area. RBridges in this area calculate this local tree based on the
link state information of this area, using RB1's nickname as the
root. Protocol behaviors for local distribution trees have been
specified in Section 4.5 of [RFC6325]. The only sole difference is that
the local distribution tree spans this area only. A multi-destination multi-
destination packet with an egress nickname of the root RBridge of a
local tree MUST NOT be leaked into Level 2 at the border RBridge.

3.2.2. Global Distribution Trees

Within Level 2, the RBridge with the highest tree root priority
advertises the set of global trees by providing a list of Level 2
RBridge nicknames just as defined in Section 4.5 of [RFC6325].

According to [RFC6325], the RBridge with the highest root priority
advertises the tree roots for a Level 1 area. There has to be a
border RBridge with the highest root tree priority in each area so
that it can advertises advertise the global tree root nicknames into the area.
Also, this border RBridge MUST advertise the set of local
distribution trees by providing another set of nicknames. Since
nicknames of global tree roots and local tree roots indicate
different flooding scopes, these two set sets MUST NOT overlap. If a
border RBridge has been assigned both as a global tree root and a
local tree root, it MUST acquire both a global tree root nickname(s)
and local tree root nickname(s). However, non-border RBridges in an
area do not differentiate between a global tree root nickname and a
local tree root nickname.

Suppose RB3 is the RBridge with the highest tree root priority within
Level 2, and RB2 is the highest tree root priority in Area X. RB2
advertises in Area X that nickname RB3 is the root of a distribution
tree. Figure 3.2 Figures 2 through Figure 3.5 5 illustrate how different RBridges view the
global distribution tree.

RB2,RB3,Rb,Rc,Rd,Re,Rk,RB44
o
/
Rz o
/
Rx o
/
RB27 o

Figure 3.2: 2: RB27's view View of the global distribution tree Global Distribution Tree

RB3,Rk,RB44
o
/
Re o
/
Rd o
/
Rc o
/
Rb o
/
RB2 o
/
Rz o
/
Rx o
/
RB27 o

Figure 3.3: 3: RB2's view View of the global distribution tree Global Distribution Tree

RB3
o
/ \
Re o o Rk
/ \
Rd o o RB44
/
Rc o
/
Rb o
/
R27,Rx,Rz,RB2 o

Figure 3.4: 4: RB3's view View of the global distribution tree Global Distribution Tree
RB3,RB27,RBx,RBz,RB2,Rb,Rc,Rd,Re
o
\
o Rk
\
o RB44

Figure 3.5: 5: RB44's view View of the global distribution tree Global Distribution Tree

The following sequence of events will occur when a multi-destination
TRILL Data packet is forwarded using the global distribution tree:

- RB27 produces a multi-destination (M bit is one) TRILL Data packet
with ingress RBridge nickname 27 and egress RBridge nickname 3.
RB27 floods this packet using the segment of the global
distribution tree that resides in Area X.

- RB2, when flooding the packet in Level 2, uses the segment of the
global distribution tree that resides in Level 2.

- RB3, when flooding the packet into Area Y, uses the segment of the
global distribution tree that resides in Area Y.

- The multicast listener RB44, when decapsulating the received
packet, learns that S is attached to nickname 27.

4. Protocol Basics and Extensions

4.1. Multilevel TRILL Basics

Multilevel TRILL builds on the multilevel feature of [IS-IS]. Border
RBridges are in both a Level 1 area and in Level 2. They establish
adjacency with Level 1 RBridges as specified in [RFC7177] and
[RFC6325]. They establish adjacency with Level 2 RBridges in exactly
the same way except that (1) for a LAN link link, the IS-IS Hellos used
are Level 2 Hello PDUs [IS-IS] and (2) for a point-to-point link link, the
Level is configured and indicated in flags in the point-to-point
Hello. The state machines for Level 1 and Level 2 adjacency are
independent
independent, and two RBridges on the same LAN link can have any
adjacency state for Level 1 and, separately, any adjacency state for
Level 2. Level 1 and Level 2 link state flooding are independent
using Level 1 and Level 2 versions of the relevant IS-IS PDUs (LSP,
CSNP, PSNP, FS-LSP, FS-CSNP FS-CSNP, and FS-PSNP). Thus FS-PSNP [RFC7356] [RFC7780]). Thus,
Level 1 link state information stays within a Level 1 area and Level
2 link state information stays in Level 2 unless there are specific
provisions for leaking (copying) information between levels. This is
why multilevel can address the TRILL scalability issues as specified
in Section 2 of [RFC8243].

The former "campus wide" minimum acceptable link size Sz is
calculated as before before: by Level 1 RBridges (including border RBridges)
using the originatingLSPBufferSize advertised in the Level 1 LSP so
it is area local in multilevel TRILL. A minimum acceptable link size
in Level 2, called Sz2, is calculated by the RBridges participating
in Level 2 in the same way as Sz is calculated but using the
originatingLSPBufferSize distributed in Level 2 LSPs.

4.2. Nickname Allocation

Level 2 RBridges contend for nicknames in the range from 0xF000
through 0xFFBF the same way as specified in [RFC6325], [RFC6325]: using Level 2
LSPs. The highest priority highest-priority border router for a Level 1 area should
contend with others in Level 2 for blocks of nicknames for the range
from 0x0001 to 0xEFFF. Blocks of 64 aligned on multiple boundaries of
multiples of 64
boundaries are RECOMMENDED in this document.

The nickname contention in Level 2 will figure out determine which blocks of
nicknames are available for an area and which blocks of nicknames are
used elsewhere. The NickBlockFlags APPsub-TLV as specified in
Section 4.3 will be used by the border RBridge(s) to announce the
nickname availability.

4.3. Nickname Announcements

Border RBridges need to exchange nickname information between Level 1
and Level 2, otherwise 2; otherwise, forwarding paths inward/outward inward or outward will not
be calculated. For this purpose, border RBridges need to fabricate
nickname announcements. Sub-TLVs used for such announcements are
specified as follows.

Besides its own nickname(s), a border RBridge MUST announce, in its
area, the ownership of all external nicknames that are reachable from
this border RBridge. These external nicknames include nicknames used
in other unique nickname areas and nicknames in Level 2. Non-border
RBridge nicknames within aggregated nickname areas are excluded.
Also, a border RBridge MUST announce, in Level 2, the ownership of
all nicknames within its area. From listening to these Level 2
announcements, border RBridges can figure out the nicknames used by
other areas.

RBridges in the TRILL base protocol use the Nickname Sub-TLV as
specified in Section 2.3.2 of [RFC7176] to announce the ownership of
nicknames. However, it becomes uneconomic to use this Sub-TLV to
announce a mass of internal/external nicknames. To address this
issue, border RBridges SHOULD make use of the NickBlockFlags APPsub-
TLV
APPsub-TLV to advertise into the Level 1 area the inclusive range of
nicknames that are available or are not available for self allocation by the
Level 1 RBridges in that area. Its structure is as follows:

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| type Type = tbd2 24 |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| length Length |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|OK| RESV |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Nickname Block 1 |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ...
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Nickname Block K |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

o Type: tbd2 24 (TRILL NickBlockFlags)

o Length: 2 + 4*K 4*K, where K is the number of nickname blocks.

o OK:

- When this bit is set to 1, the blocks of nicknames in this
APPsub-TLV are associated to the border RBridge's attached
Level 1 area. The APPsub-TLV will be advertised in both
Level 1 and Level 2. For nicknames that fall in the ranges or
of the nickname blocks, RBridges of Level 2 always route to
the originating border RBridge, just as if this border
RBridge owns these nicknames.

- When this bit is set to 0, it indicates that the nicknames
covered by the nickname blocks are being used in Level 2 or
other areas so that they are not available for use in the
border RBridge's attached Level 1 area. The APPsub-TLV will
be advertised into Level 1 only. For nicknames that fall in
the ranges of the nickname blocks, RBridges of the area
always route to the originating border RBridge, just as if
this border RBridge owns these nicknames. For nicknames in
these ranges, other RBridges will deem that they are owned by
the originating border RBridge. The paths to nicknames that
fall in these ranges will be calculated to reach the
originating border RBridge. TRILL Data packets with egress
nicknames that are neither in these ranges nor announced by
any RBridge in the area MUST be discarded.

o RESV: reserved for future flag allocation. MUST be sent as
zero and ignored on receipt.

o Nickname Block: a starting and ending nickname as follows:

+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| starting nickname |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ending nickname |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

Nickname Sub-TLV as specified in Section 2.3.2 of [RFC7176] is still
allowed to be used used, given the above NickBlockFlags APPsub-TLV is
being used.

There might be multiple border RBridges connected to the same area.
Each border RBridges RBridge may advertise a subset of the entire
internal/external nickname space in order to realize load balance.
However, optimization of such load balance is an implementation issue
and is out outside the scope of this document.

As specified in Section 4.2.6 of [RFC6325], multiple border RBridges
may claim the same nicknames outward outwardly and/or inward. inwardly. Other
RBridges add those nicknames as if they are attached to all of those
border RBridges.

4.4. Capability Indication

All border RBridge RBridges MUST understand the NickBlockFlags APPsub-TLV. Non
border
Non-border RBridges in an area should understand the NickBlockFlags
APPsub-TLV. If an RBridge within an area understands the
NickBlockFlags APPsub-TLV, it MUST indicate this capability by
announcing it in its TRILL-VER Sub-TLV. (See Section 7). 7.)

If there are RBridges that do not understand the NickBlockFlags
APPsub-TLV, border RBridges of the area MUST also use the traditional
Nickname Sub-TLV [RFC7176] to announce into the area those nicknames
covered by the nickname blocks of the NickBlockFlags APPsub-TLV whose
OK is 0. The available range of nicknames for this area should be
configure
configured on these traditional RBridges.

5. Mix with Aggregated nickname Nickname Areas

The design of TRILL multilevel allows a mixture of unique nickname
areas and aggregated nickname areas (see Section 1.2 of [RFC8243]).
Usage of nickname space MUST be planed planned so that nicknames used in any
one unique nickname area and Level 2 are never used in any other
areas which includes
areas, including unique nickname areas as well as aggregated nickname
areas. In other words, nickname re-usage reusage is merely allowed among
aggregated nickname areas.

Border RBridges of an aggregated area MUST announce nicknames heard
from Level 2 into their area like just like an a unique nickname border
RBridge. But However, these RBridges do not announce nicknames of their
area into Level 2.

Each border RBridge of the aggregated areas will appear on the global
tree, as specified in Section 4.1, as a single node. The global
trees for unique nickname areas span unique nickname areas and Level
2 but never reach the inside of aggregated areas.

6. Security Considerations

Since TRILL multilevel uses the existing IS-IS multilevel facilities
[IS-IS], flooding of control traffic for link state link-state information is
automatically confined to a Level 1 area or to Level 2 except (for (except for
limited types of information that can be specifically flagged for
wider flooding). This addresses the TRILL scalability issues as
specified in Section 2 of [RFC8243] [RFC8243], and also, except for the wider
flooding case, this confines the scope of the effects of malicious
events that could be communicated through the link state. However,
due to the nature fact that unique nickname areas share a common nickname
space, border RBridges still have to leak nickname information
between levels. Such leaking means that nickname related nickname-related events in
one area can affect other areas.

For this purpose, border RBridges need to fabricate the nickname
announcements as specified in Section 4.3. Malicious devices may
also fake the NickBlockFlags APPsub-TLV to announce a range of
nicknames. By doing this, the attacker can attract TRILL data
packets that are were originally sent to reach a bunch of other RBridges. For
this reason, RBridges SHOULD be configured to use the IS-IS
Authentication TLV (10) in the IS-IS PDUs, particularly those
containing the NickBlockFlags APPsub-TLV, so that IS-IS security ([RFC5310])
[RFC5310] can be used to authenticate those PDUs and discard them if
they are forged.

If border RBridges do not prune multi-destination distribution tree
traffic in Data Labels that are configured to be area local, then
traffic that should have been contained within an area might be
wrongly delivered to end stations in that Data Label in other areas,
that areas.
That is, the Data Label would no longer be area local. This would
generally violate security constraints that require traffic to be
delivered only to end stations in that Data Label in a single area.

For general TRILL Security Considerations, see [RFC6325].

7. IANA Considerations

IANA is requested to register has registered a new flag bit under the TRILL-VER Sub-
TLV "TRILL-VER Sub-TLV
Capability Flags Flags" registry.

Bit Description Reference
--- ----------- ---------
tbd1
5 Able to handle the [This document] RFC 8397
NickBlockFlags
APPsub-TLV

IANA is requested to assign has assigned a new type for the NickBlockFlags APPsub-
TLV APPsub-TLV from
the range available below 256 and add the following entry to the
"TRILL APPsub-TLV Types under IS-IS TLV 251 Application Identifier 1"
registry as follows:

Type Name Reference
---- ------ ---------
tbd2
24 NickBlockFlags [This document] RFC 8397

8. References

8.1. 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, <http://www.rfc-
editor.org/info/rfc2119>.
<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,
<http://www.rfc-editor.org/info/rfc6325>.
<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>.

[RFC7176] 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,
DOI 10.17487/RFC7176, May 2014, <http://www.rfc-
editor.org/info/rfc7176>.

[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, <http://www.rfc-
editor.org/info/rfc7172>.
<https://www.rfc-editor.org/info/rfc7176>.

[RFC7177] Eastlake 3rd, D., Perlman, R., Ghanwani, A., Yang, H., and
V. Manral, "Transparent Interconnection of Lots of Links
(TRILL): Adjacency", RFC 7177, DOI 10.17487/RFC7177, May
2014, <http://www.rfc-editor.org/info/rfc7177>. <https://www.rfc-editor.org/info/rfc7177>.

[RFC7968] Li, Y., Eastlake 3rd, D., Hao, W., Chen, H., and S.
Chatterjee, "Transparent Interconnection of Lots of Links
(TRILL): Using Data Labels for Tree Selection for Multi-
Destination Data", RFC 7968, DOI 10.17487/RFC7968, August
2016, <http://www.rfc-editor.org/info/rfc7968>. <https://www.rfc-editor.org/info/rfc7968>.

[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>.

[IS-IS] International Organization for Standardization,
"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,
November 2002.

8.2. Informative References

[SingleN] Zhang, M., Eastlake, D., et al, "Single "Transparent
Interconnection of Lots of Links (TRILL) Single Area
Border RBridge Nickname for TRILL Multilevel", draft-ietf-trill-
multilevel-single-nickname,
multilevel-single-nickname-05, Work in Progress. Progress, January
2018.

[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, DOI 10.17487/RFC5310, February
2009,
<http://www.rfc-editor.org/info/rfc5310>. <https://www.rfc-editor.org/info/rfc5310>.

[RFC7356] Ginsberg, L., Previdi, S., and Y. Yang, "IS-IS Flooding
Scope Link State PDUs (LSPs)", RFC 7356,
DOI 10.17487/RFC7356, September 2014,
<https://www.rfc-editor.org/info/rfc7356>.

[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>.

[RFC8243] Perlman, R., Eastlake 3rd, D., Zhang, M., Ghanwani, A.,
and H. Zhai, "Alternatives for Multilevel Transparent
Interconnection of Lots of Links (TRILL)", RFC 8243,
DOI 10.17487/RFC8243, September 2017, <https://www.rfc-
editor.org/info/rfc8243>.

9.
<https://www.rfc-editor.org/info/rfc8243>.

Contributors

Margaret Cullen
Painless Security
14 Summer St. Suite 202
Malden, MA 02148
United States of America

Email: margaret@painless-security.com

Author's

Authors' Addresses

Mingui Zhang
Huawei Technologies
No. 156 Beiqing Rd., Haidian District
Beijing 100095
China

Phone: +86-13810702575
Email: zhangmingui@huawei.com

Donald E. Eastlake 3rd
Huawei Technologies
155 Beaver Street
Milford, MA 01757
United States of America

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

Radia Perlman
Dell EMC
176 South Street
Hopkinton, MA 01748
United States of America

Email: radia@alum.mit.edu
Hongjun Zhai
Jinling Institute of Technology
99 Hongjing Avenue, Jiangning District
Nanjing, Jiangsu 211169
China

Email: honjun.zhai@tom.com

Dongxin Liu
China Telcom Telecom Co., Ltd
109 West Zhongshan Ave, Tianhe District
Guangzhou 510630
P.R.
China

Email: liudx@gsta.com