INTERNET-DRAFT                                            Mohammed Umair
Intended Status: Informational                  Kingston Smiler Selvaraj
                                                              IPInfusion
                                                     Donald Eastlake 3rd
                                                               Lucy Yong
                                                     Huawei Technologies
Expires: September 10, 2016                                March 9, 2016


                 TRILL Transparent Transport over MPLS
               <draft-muks-trill-transport-over-mpls-02>


Abstract

   This document specifies how to interconnect multiple Transparent
   Interconnection of Lots of links (TRILL) sites with an intervening
   MPLS network using existing TRILL and VPLS standards. This draft
   addresses two problems as follows:

   1) Providing connection between more than two TRILL sites that
   are separated by MPLS provider network.

   2) Providing a single logical virtualized TRILL network for
   different tenants that are separated by an MPLS provider network.




Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at



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   http://www.ietf.org/shadow.html


Copyright and License Notice

   Copyright (c) 2016 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
   (http://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  . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . .  4
   2. TRILL Over MPLS Model . . . . . . . . . . . . . . . . . . . . .  5
   3. VPLS Model  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1. Entities in the VPLS Model  . . . . . . . . . . . . . . . .  7
     3.3. TRILL Adjacency for VPLS model  . . . . . . . . . . . . . .  8
     3.4. MPLS encapsulation for VPLS model . . . . . . . . . . . . .  8
     3.5. Loop Free provider PSN/MPLS.  . . . . . . . . . . . . . . .  8
     3.6. Frame processing. . . . . . . . . . . . . . . . . . . . . .  8
   4. VPTS Model  . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     4.1. Entities in the VPTS Model  . . . . . . . . . . . . . . . . 10
       4.1.1. TRILL Intermediate Routers (TIR)  . . . . . . . . . . . 11
       4.1.2. Virtual TRILL Switch/Service Domain (VTSD)  . . . . . . 11
     4.2. TRILL Adjacency for VPTS model  . . . . . . . . . . . . . . 11
     4.3. MPLS encapsulation for VPTS model . . . . . . . . . . . . . 11
     4.4. Loop Free provider PSN/MPLS.  . . . . . . . . . . . . . . . 12
     4.5. Frame processing. . . . . . . . . . . . . . . . . . . . . . 12
       4.5.1. Multi-Destination Frame processing  . . . . . . . . . . 12
       4.5.2. Unicast Frame processing  . . . . . . . . . . . . . . . 12
   5. Extensions to TRILL Over Pseudowires [RFC7173]  . . . . . . . . 12
   6. VPTS Model Versus VPLS Model  . . . . . . . . . . . . . . . . . 12
   7. Packet processing between pseudowires . . . . . . . . . . . . . 13
   8. Security Considerations . . . . . . . . . . . . . . . . . . . . 14
   9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 14
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 14



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     10.2. Informative References . . . . . . . . . . . . . . . . . . 15
   Appendix Z: Change History . . . . . . . . . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
















































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1. Introduction

   The IETF Transparent Interconnection of Lots of Links (TRILL)
   protocol [RFC6325] [RFC7177] [RFC7780] provides transparent
   forwarding in multi-hop networks with arbitrary topology and link
   technologies using a header with a hop count and link-state routing.
   TRILL provides optimal pair-wise forwarding without configuration,
   safe forwarding even during periods of temporary loops, and support
   for multipathing of both unicast and multicast traffic. Intermediate
   Systems (ISs) implementing TRILL are called Routing Bridges(RBridges)
   or TRILL Switches

   This draft, in conjunction with [RFC7173] on TRILL Transport using
   Pseudowires, addresses two problems:

   1) Providing connection between more than two TRILL sites belongs to
   a single TRILL network that are separated by an MPLS provider network
   using [RFC7173]. (Herein also called problem statement 1.)

   2) Providing a single logical virtualized TRILL network for different
   tenants that are separated by an MPLS provider network. In short
   providing connection between TRILL sites belonging to a
   tenant/tenants over a MPLS provider network. (Herein also called
   problem statement 2.)

   A tenant is the administrative entity on whose behalf their
   associated services are managed. Here tenant refers to a TRILL campus
   that is segregated from other tenants for security reasons.

   A key multi-tenancy requirement is traffic isolation so that one
   tenant's traffic is not visible to any other tenant. This draft also
   addresses the problem of multi-tenancy by isolating one tenant's
   traffic from the other.

1.1. Terminology

   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 [RFC2119].


    Acronyms used in this document include the following:

        AC         - Attachment Circuit [RFC4664]

        Data Label  - VLAN or FGL

        ECMP        - Equal Cost Multi Path



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        FGL        - Fine-Grained Labeling [RFC7172]

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

        LDP         - Label Distribution Protocol

        LAN         - Local Area Network

        MPLS        - Multi-Protocol Label Switching

        PE          - Provider Edge Device

        PPP         - Point-to-Point Protocol [RFC1661]

        PSN         - Packet Switched Network

        PW          - Pseudowire [RFC4664]

        TIR         - TRILL Intermediate Router
                     (Devices that has both IP/MPLS and TRILL
                        functionality)

        TRILL       - Transparent Interconnection of Lots of Links
                    OR Tunneled Routing in the Link Layer

        TRILL Site  - A part of a TRILL campus that contains at
                    least one RBridge.

        VLAN        - Virtual Local Area Network

        VPLS        - Virtual Private LAN Service

        VPTS        - Virtual Private TRILL Service

        VSI        - Virtual Service Instance [RFC4664]

        VTSD        - Virtual TRILL Switch Domain
                            OR Virtual TRILL Service Domain
                    A Virtual RBridge that segregates one tenant's
                    TRILL database as well as traffic from the other.

        WAN        - Wide Area Network



2. TRILL Over MPLS Model

   TRILL Over MPLS can be achieved by two different ways.



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      a) VPLS Model for TRILL
      b) VPTS Model/TIR Model


   Both these models can be used to solve the problem statement 1 and 2.
   Herein the VPLS Model for TRILL is also called Model 1 and the VPTS
   Model/TIR Model is also called Model 2.

3. VPLS Model

   Figure 1 shows the topological model of TRILL over MPLS using VPLS
   model. The PE routers in the below topology model should support all
   the functional Components mentioned in [RFC4664].



       +-----+                                               +-----+
       | RBa +---+      ...........................      +---| RBb |
       +-----+   |      .                         .      |   +-----+
       Site 1    |    +----+                   +----+    |    Site 2
                 +----|PE1 |                   |PE2 |----+
                      +----+    MPLS Cloud     +----+
                        .                         .
                        .         +----+          .
                        ..........|PE3 |...........
                                  +----+      ^
                                     |        |
                                     |        +-- Emulated LAN
                                  +-----+
                                  | RBc |
                                  +-----+
                                  Site 3

             Figure 1: Topological Model of TRILL over MPLS
                         connecting three TRILL Sites


 Figure 2 below shows the topological model of TRILL over MPLS to
 connect multiple TRILL sites belonging to a tenant (tenant here is a
 campus, not a Data label). VSI1 and VSI2 are two Virtual Service
 Instances that segregate Tenant1's traffic from other tenant traffic.
 VSI1 will maintain its own database for Tenant1, similarly VSI2 will
 maintain its own database for Tenant2.








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       +-----+         ............................          +-----+
       |RBat1+---+     . ++++++++++++++++++++++++ .      +---|RBbt1|
       +-----+   |     . +                      + .      |   +-----+
 Tenant1 Site 1  |    +----+                   +----+    | Tenant1 Site2
                 +----|VSI1|                   |VSI1|----+
                 +----|VSI2|    MPLS  Cloud    |VSI2|----+
                 |    +----+                   +----+    |
       +-----+   |     . +                       + .     |   +-----+
       |RBat2+---+     . +++++++++ +----+ ++++++++ .     +---|RBbt2|
       +-----+         ............|VSI1|...........         +-----+
 Tenant2 Site 2               +----|VSI2|----+     ^      Tenant2 Site2
                              |    +----+    |     |
                              |              |     |
                          +-----+         +-----+  +-----Emulated
                          |RBct2|         |RBct1|          LAN
                          +-----+         +-----+
                       Tenant2 Site 3     Tenant1 Site 3


      .... VSI1 Path
      ++++ VSI2 Path

         Figure 2: Topological Model for VPLS Model
                 connecting 2 Tenants with 3 sites each


In this model, TRILL sites are connected to VPLS-capable PE devices that
provide a logical interconnect, such that TRILL RBridges belonging to a
specific tenant connected via an single bridged Ethernet. These devices
are the same as PE devices specified in [RFC4026]. The Attachment
Circuit ports of PE Routers are layer 2 switch ports that are connected
to the RBridges at a TRILL site. Here each VPLS instance looks like an
emulated LAN. This model is similar to connecting different RBridges
(TRILL sites) by a layer 2 bridge domain (multi access link) as
specified in [RFC6325]. This model doesn't requires any changes in PE
routers to carry TRILL packets, as TRILL packets will be transferred
transparently.


3.1. Entities in the VPLS Model

The PE (VPLS-PE) and CE devices are defined in [RFC4026].

The Generic L2VPN Transport Functional Components like Attachment
Circuits, Pseudowires, VSI etc. are defined in [RFC4664].

The RB (RBridge) and TRILL Sites are defined in [RFC6325] as updated by
[RFC7780].



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3.3. TRILL Adjacency for VPLS model

As specified in section 3 of this document, the MPLS cloud looks like an
emulated LAN (also called multi-access link or broadcast link). This
results in RBridges at different sites looking like they are connected
by a multi-access link. With such interconnection, the TRILL adjacency
over the link are automatically discovered and established through TRILL
IS-IS control messages [RFC7177]. These IS-IS control messages are
transparently forwarded by the VPLS domain, after doing MPLS
encapsulation specified in the section 3.4.


3.4. MPLS encapsulation for VPLS model

MPLS encapsulation over Ethernet pseudowire is specified in [RFC7173]
Appendix A, and requires no change in the frame format.


3.5. Loop Free provider PSN/MPLS.

No explicit handling is required to avoid loop free topology. Split
Horizon technique specified in [RFC4664] will take care of avoiding
loops in the provider PSN network.


3.6. Frame processing.

The PE device transparently process the TRILL control and data frames.
Procedures to forward the frames are defined in [RFC4664]


4. VPTS Model

The (Virtual Private TRILL Service) VPTS is a L2 TRILL service, that
emulates TRILL service across a Wide Area Network (WAN). VPTS is similar
to what VPLS does for bridge domain. VPLS provides "Virtual Private LAN
Service" for different customers. VPTS provides "Virtual Private TRILL
Service" for different TRILL tenants.

Figure 3 shows the topological model of TRILL over MPLS using VPTS. In
this model the PE routers are replaced with TIR (TRILL Intermediate
Router) and VSI is replaced with VTSD (Virtual TRILL Switch Domain). The
TIR devices must be capable of supporting both MPLS and TRILL and is
defined in section 4.1.1. The TIR devices are interconnected via PWs and
appear as a unified emulated TRILL campus with each VTSD inside a TIR
equivalent to a RBridge.

Some of the reasons for interconnecting TRILL Sites without isolating



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TRILL Control plane of one TRILL site with other is as described below.

1) Nickname Uniqueness: One of the basic requirements of TRILL is that,
RBridge Nicknames should be unique with in the campus. If we segregate
control plane of one TRILL site from other TRILL site and provide
interconnection between these sites, it may result in Nickname
collision.

2) Distribution Tree and its pruning:  When a TRILL Data packet traverse
a Distribution Tree, it will adhere to it even in other TRILL site. If
no end-station service is enabled for a particular Data Label in a TRILL
site, Distribution Tree may be pruned and TRILL data packets of that
particular Data Label might never get to other TRILL sites. RPF check
will always be performed on the packets that are received TIR's through
pseudowires.

3) Hop Count values: When a TRILL data packet is received over a
pseudowire by a TIR, the TIR does the processing of Hop Count defined in
[RFC6325] and will not perform any resetting of Hop Count.






       +-----+                                               +-----+
       | RBa +---+      ...........................      +---| RBb |
       +-----+   |      .                         .      |   +-----+
       Site 1    |    +----+                   +----+    |    Site 2
                 +----|TIR1|                   |TIR2|----+
                      +----+    MPLS Cloud     +----+
                        .                         .
                        .         +----+          .
                        ..........|TIR3|...........
                                  +----+      ^
                                     |        |
                                     |        +-- Emulated TRILL
                                  +-----+
                                  | RBc |
                                  +-----+
                                  Site 3

             Figure 3: Topological Model of VPTS/TIR
                        connecting three TRILL Sites

 In the above figure (Figure 3) Site1, Site2 and Site3 (running TRILL
 protocol) are connected to TIR Devices. These TIR devices along with
 the MPLS cloud looks like an unified emulated TRILL campus. Only the PE



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 devices in the MPLS network should be replaced with TIRs so the
 intermediate P routers are agnostic to the TRILL protocol.

 Figure 4 below extends the topological model of TRILL over MPLS to
 connect multiple TRILL sites belonging to a tenant (tenant here is a
 campus, not a Data label) using VPTS model. VTSD1 and VTSD2 are two
 Virtual TRILL Switch Domains (Virtual RBridges) that segregate
 Tenant1's traffic from Tenant2's traffic. VTSD1 will maintain its own
 TRILL database for Tenant1, similarly VTSD2 will maintain its own TRILL
 database for Tenant2.




    +-----+          ............................         +-----+
    |RBat1+---+      . ######################## .     +---|RBbt1|
    +-----+   |      . #                      # .     |   +-----+
Tenant1 Site 1|    +-----+                 +-----+    |  Tenant1 Site 2
              +----|VTSD1|                 |VTSD1|----+
              +----|VTSD2|   MPLS  Cloud   |VTSD2|----+
              |    +-----+                 +-----+    |
    +-----+   |      . #                       # .    |   +-----+
    |RBat2+---+      . #########+-----+######### .    +---|RBbt2|
    +-----+          ...........|VTSD1|...........        +-----+
Tenant2 Site2               +---|VTSD2|----+     ^       Tenant2 Site 2
                            |   +-----+    |     |
                            |              |     |
                        +-----+         +-----+  +-----Emulated
                        |RBct2|         |RBct1|          TRILL
                        +-----+         +-----+
                    Tenant2 Site 3     Tenant1 Site 3


        .... VTSD1 Connectivity
        #### VTSD2 Connectivity

                  Figure 4: Topological Model of VPTS/TIR
                 connecting 2 tenants with three TRILL Sites



4.1. Entities in the VPTS Model

The CE devices are defined in [RFC4026].

The Generic L2VPN Transport Functional Components like Attachment
Circuits, Pseudowires etc. are defined in [RFC4664].




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The RB (RBridge) and TRILL Campus are defined in [RFC6325] as updated by
[RFC7780].

This model introduces two new entities called TIR and VTSD.


4.1.1. TRILL Intermediate Routers (TIR)

The TIRs [TRILL Intermediate Routers] must be capable of running both
VPLS and TRILL protocols. TIR devices are a superset of the VPLS-PE
devices defined in [RFC4026] with the additional functionality of TRILL.
The VSI instance that provides transparent bridging functionality in the
PE device is replaced with VTSD in TIR.




4.1.2. Virtual TRILL Switch/Service Domain (VTSD)

The VTSD [Virtual Trill Switch Domain] is similar to VSI (layer 2
bridge) in VPLS model, but this acts as a TRILL RBridge. The VTSD is a
superset of VSI and must support all the functionality provided by the
VSI as defined in [RFC4026]. Along with VSI functionality, the VTSD must
be capable of supporting TRILL protocols and form TRILL adjacencies. The
VTSD must be capable of performing all the operations that a standard
TRILL Switch can do.

One VTSD instance per tenant must be maintained, when multiple tenants
are connected to a TIR. The VTSD must maintain all the information
maintained by the RBridge on a per tenant basis. The VTSD must also take
care of segregating one tenant traffic from other. Each VTSD should have
its own nickname, If a TIR supports 10 TRILL tenants, it needs to be
assigned with ten TRILL nicknames and run ten copies of TRILL protocols,
one for each.



4.2. TRILL Adjacency for VPTS model

The VTSD must be capable of forming TRILL adjacency with other VTSDs
present in its peer VPTS neighbor, and also the neighbor RBridges
present in the TRILL sites. The procedure to form TRILL Adjacency is
specified in [RFC7173] and [RFC7177].


4.3. MPLS encapsulation for VPTS model

MPLS encapsulation over pseudowire is specified in [RFC7173], and



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requires no changes in the frame format.


4.4. Loop Free provider PSN/MPLS.

This model isn't required to employ Split Horizon mechanism in the
provider PSN network, as TRILL takes care of Loop free topology using
Distribution Trees. Any multi-destination packet will traverse a
distribution tree path. All distribution trees are calculated based on
TRILL base protocol standard [RFC6325] as updated by [RFC7780].


4.5. Frame processing.

This section specifies multi-destination and unicast frame processing in
VPTS/TIR model.


4.5.1. Multi-Destination Frame processing

Any multi-destination (unknown unicast, multicast or broadcast) packets
inside VTSD should be processed or forwarded through any one of the
distribution trees. If any multi-destination packet is received from the
wrong pseudowire at a VTSD, the TRILL protocol running in VTSD will
perform a RPF check as specified in [RFC7780] and drops the packet.

Pruning mechanism in Distribution Trees, as specified in [RFC6325] and
[RFC7780] can also be used to avoid forwarding of multi-destination data
packets on the branches where there are no potential destinations.

4.5.2. Unicast Frame processing

Unicast packets must be forwarded in same way they get forwarded in a
standard TRILL Campus as specified in [RFC6325]. If multiple equal cost
paths are available over pseudowires to reach destination, then VTSD
should be capable of doing ECMP for them.


5. Extensions to TRILL Over Pseudowires [RFC7173]

The [RFC7173] mentions how to interconnect a pair of Transparent
Interconnection of Lots of Links (TRILL) switch ports using pseudowires.
This document explains, how to connect multiple TRILL sites (not limited
to only two sites) using the mechanisms and encapsulations defined in
[RFC7173].


6. VPTS Model Versus VPLS Model



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VPLS Model uses a simpler loop breaking rule: the "split horizon" rule,
where a PE must not forward traffic from one PW to another in the same
VPLS mesh.

An issue with the above rule is that if a pseudowire between PEs fails,
frames will not get forwarded between the PEs where pseudowire went
down.

VPTS solves this problem, as the VPTS Model uses distribution Trees for
loop free topology. Hence the frames reach all TIRs even when any one of
the pseudowires fails in the mesh.

If equal cost paths are available to reach a site over pseudowires, VPTS
Model can use ECMP for processing of frames over pseudowires.


7. Packet processing between pseudowires

Whenever a packet gets received over a pseudowire, VTSD will decapsulate
the MPLS headers followed by checking the TRILL header. If the egress
nickname in the TRILL header is for a TRILL site located beyond another
pseudowire, then VTSD will encapsulate with new MPLS headers and send it
across the proper pseudowire.

For example in figure 3, consider that the pseudowire between TIR1 and
TIR2 fails, Then TIR1 will communicate with TIR2 via TIR3, whenever
packets which are destined to TIR3 gets received from pseudowire between
TIR1 and TIR3, VTSD inside TIR3 will decapsulate the MPLS headers, then
check the TRILL header's egress nickname field. If egress nickname is
destained for the RBridge in site3 then the packet will be sent to RBc,
if egress nickname is located at site2, VTSD will add MPLS headers for
the pseudowire between TIR3 and TIR2 and forward the packet on that
pseudowire.


















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8. Security Considerations

For general TRILL security considerations, see [RFC6325]

For transport of TRILL by Pseudowires security consideration, see
[RFC7173].

For general VPLS security considerations, see [RFC4762]

Since the VPTS Model uses Distribution trees for processing of multi-
destination data packets, it is always advisable to have at least one
Distribution tree root to be located in every TRILL site. This will
avoid data packets getting received at TRILL sites where end-station
service is not enabled for that data packet.




9. IANA Considerations

This document requires no IANA actions. RFC Editor: Please delete this
section before publication


10. References

10.1. Normative References


   [IS-IS]   "Intermediate system to Intermediate system routeing
              information exchange protocol for use in conjunction with
              the Protocol for providing the Connectionless-mode Network
              Service (ISO 8473)", ISO/IEC 10589:2002, 2002".

   [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>.

   [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,
              <http://www.rfc-editor.org/info/rfc4762>.

   [RFC7173]  Yong, L., Eastlake 3rd, D., Aldrin, S., and J. Hudson,
              "Transparent Interconnection of Lots of Links (TRILL)
              Transport Using Pseudowires", RFC 7173, DOI
              10.17487/RFC7173, May 2014, <http://www.rfc-



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              editor.org/info/rfc7173>.

   [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>.

   [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>.


   [RFC7780]  EEastlake 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,
              <http://www.rfc-editor.org/info/rfc7780>.


10.2. Informative References

   [RFC3985]  Bryant, S., Ed., and P. Pate, Ed., "Pseudo Wire Emulation
              Edge-to-Edge (PWE3) Architecture", RFC 3985, DOI
              10.17487/RFC3985, March 2005, <http://www.rfc-
              editor.org/info/rfc3985>.

   [RFC4026]  Andersson, L. and T. Madsen, "Provider Provisioned Virtual
              Private Network (VPN) Terminology", RFC 4026, DOI
              10.17487/RFC4026, March 2005, <http://www.rfc-
              editor.org/info/rfc4026>.

   [RFC4448]  Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron,
              "Encapsulation Methods for Transport of Ethernet over MPLS
              Networks", RFC 4448, DOI 10.17487/RFC4448, April 2006,
              <http://www.rfc-editor.org/info/rfc4448>.

   [RFC4664]  Andersson, L., Ed., and E. Rosen, Ed., "Framework for
              Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664, DOI
              10.17487/RFC4664, September 2006, <http://www.rfc-
              editor.org/info/rfc4664>.

   [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>.




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Appendix Z: Change History

   From -00 to -01


         1. Did some editorial fixes

         2. Changed Intended Status from "Proposed Standard"
            to "Informational"

         3. Provided reasons for interconnecting TRILL
            Sites without isolating TRILL Control plane, in section 4.

         4. Updated section 4.1.2

         5. Added section for Frame processing between pseudowires.

         6. Fix references for RFCs, etc.

         7. Add this Change History Appendix.


      From -01 to -02

         Editorial improvements.




Authors' Addresses


   Mohammed Umair
   IPInfusion
   RMZ Centennial
   Mahadevapura Post
   Bangalore - 560048 India

   EMail: mohammed.umair2@gmail.com



   Kingston Smiler Selvaraj
   IPInfusion
   RMZ Centennial
   Mahadevapura Post
   Bangalore - 560048 India




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   EMail: kingstonsmiler@gmail.com


   Donald E. Eastlake 3rd
   Huawei Technologies
   155 Beaver Street
   Milford, MA  01757
   USA

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


   Lucy Yong
   Huawei Technologies
   5340 Legacy Drive
   Plano, TX  75024
   USA

   Phone: +1-469-227-5837
   EMail: lucy.yong@huawei.com






























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