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Versions: 00 01                                                         
Network Working Group                                             X. Wan
Internet-Draft                                                   X. Yang
Intended status: Standards Track                HangZhou H3C Co. Limited
Expires: December 10, 2012                                     V. Manral
                                                               A. Retana
                                                     Hewlett-Packard Co.
                                                            June 8, 2012


                        Extending TRILL over WAN
                     draft-xl-trill-over-wan-01.txt

Abstract

   TRILL is a key technology for large-scale layer 2 networking within a
   data center, TRILL over WAN_(ToW) provides a scalable and simple
   solution that interconnect multiple TRILL networks to form a single
   TRILL domain using the currently deployed enterprise or service
   provider networks.  This document provides an overview of this
   solution.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on December 10, 2012.

Copyright Notice

   Copyright (c) 2012 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



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   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.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Control Plane  . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Provider Control Plane . . . . . . . . . . . . . . . . . .  5
     3.2.  Overlay Control Plane  . . . . . . . . . . . . . . . . . .  5
       3.2.1.  Edge Device Discovery and Adjacency setup  . . . . . .  5
       3.2.2.  Control Plane Packet Encapsulation and Relay . . . . .  5
   4.  Data Plane . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     4.1.  Encapsulation  . . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Forwarding Process . . . . . . . . . . . . . . . . . . . .  8
       4.2.1.  Forwarding from an Internal Link to the Overlay  . . .  8
       4.2.2.  Forwarding from the Overlay Link to an Internal
               Link . . . . . . . . . . . . . . . . . . . . . . . . .  8
       4.2.3.  Multicast Packet Flows . . . . . . . . . . . . . . . .  8
       4.2.4.  Broadcast Packet Flows . . . . . . . . . . . . . . . .  8
       4.2.5.  Mac Address Learning . . . . . . . . . . . . . . . . .  8
       4.2.6.  Multi-homing . . . . . . . . . . . . . . . . . . . . .  8
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
     6.1.  Failure Separation . . . . . . . . . . . . . . . . . . . . 10
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
   8.  Normative References . . . . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11




















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1.  Overview

   TRILL over WAN is a technology for supporting L2 VPNs over an L2/L3
   infrastructure.  It provides an "over-the-top" method of doing
   virtualization among several sites where the routing and forwarding
   state is maintained at the network edge, but not within the site or
   in the core.

   TRILL over WAN can reside in a small number of device at the edge
   between TRILL sites and the core, we call these devices "Joint
   Devices" which perform typical transit Rbridges functions(nickname-
   based forwarding) and perform overlay functions on their core facing
   interfaces.

   TRILL traffic which requires traversing the WAN to reach its
   destination, is prepended with an IP header.  As shown in figure1, if
   a destination RBridge(Nickname) is reachable via Joint Device S2(with
   a core facing IP address of IPB), other Joint Devices forwarding
   traffic to such Rbridge will add on IP header with a destination IP
   address of IPB and forward the traffic into the core.  The core will
   forward traffic based on IP address IPB, once the traffic makes it to
   Joint Device S2 it will be stripped of the overlay IP header and it
   will be forwarded into the site in the same way a regular RBridge
   would forward a packet.  Broadcast or multicast traffic is
   encapsulated with a multicast header and follows a similar process.



            +---+     +---+IPA  --------- IPB +---+     +---+
            |S10|-----|S1 |----/ IP Core \----|S2 |-----|S20|
            +---+  ^  +---+    \ Network /    +---+  ^  +---+
                   |            ---------            |
                   |                                 |
                   |           +------------+        |
                   |           |   DA=IPB   |        |
                   |           +------------+        |
                   |           |   SA=IPA   |        |
             +------------+    +------------+    +------------+
             |Outer Eth.  |    |Outer Eth.  |    |Outer Eth.  |
             |Header      |    |Header      |    |Header      |
             +------------+    +------------+    +------------+
             |TRILL Header|    |TRILL Header|    |TRILL Header|
             +------------+    +------------+    +------------+
             |Inner Eth.  |    |Inner Eth.  |    |Inner Eth.  |
             |Frame       |    |Frame       |    |Frame       |
             +------------+    +------------+    +------------+





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                      Figure 1: Traffic encapsulation


   The key piece that TRILL over WAN adds is the state to map a given
   egress Nickname to an IP address of the Joint Device behind which
   that egress Nickname is located.  TRILL over WAN forwarding is a
   function of mapping a destination Nickname to a Joint Device IP
   address in the overlay network.

   To achieve this, a control plane is required to exchange the
   reachability information among different Joint Devices.  After Joint
   Device discovery and adjacency setup, the virtual links to neighbor
   Joint Devices will be treated as TRILL interface, and the TRILL's
   control plane runs over these virtual links.  Through these steps,
   all the Rbridges in multiple site forms a single TRILL domain.  Each
   Rbridge (including Joint Device) calculates its TRILL forwarding
   table independently.  Figure 2 shows what the resulting forwarding
   tables look like in a simple example.



              +---+ L11+---+IPA  --------- IPB +---+ L21+---+
              |S10|----|S1 |----/ IP Core \----| S2|----|S20|
              +---+    +---+    \ Network /    +---+    +---+
                                 ---------


              S1                        S2
              +----------------------+  +-------------------+
              |Nickname   |Interface |  |Nickname |Interface|
              +----------------------+  +-------------------+
              |   S10     |   L11    |  | S10     |  IPA    |
              +----------------------+  +-------------------+
              |   S20     |   IPB    |  | S20     |  L21    |
              +----------------------+  +-------------------+
              |   S1      |   self   |  | S1      |  IPA    |
              +----------------------+  +-------------------+
              |   S2      |   IPB    |  | S2      |  self   |
              +----------------------+  +-------------------+


                        Figure 2: Forwarding Tables


   TRILL over WAN supports multi-homing for sites where one or more of
   the Joint Devices connected to core network.  It can support active-
   active multi-homing capability and loop elimination by nature of
   TRILL.  No need to add other extra mechanism.



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2.  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].

   [[anchor2: NOTE TO RFC EDITOR: Please remove the following text
   before publication.]]
   Some ideas of this specification is being discussed on the EAI
   mailing list.  See https://www1.ietf.org/mailman/listinfo/ima for
   information about subscribing.  The list's archive is at
   http://www1.ietf.org/mail-archive/web/ima/index.html.


3.  Control Plane

3.1.  Provider Control Plane

   The provider control plane enables unicast reachability among the
   Joint Devices and also provides the multicast group than makes Joint
   Devices adjacent from the overlay control plane perspective.  It also
   provides the multicast trees in the core that will be used for
   optimal forwarding of the TRILL data traffic.

3.2.  Overlay Control Plane

   The overlay control plane provides auto-discovery of the Joint
   Devices that are members of an overlay VPN.

   The TRILL control plane traffic between Joint Devices of different
   sites will be carried over the virtual link.

   Detailed to be added.

3.2.1.  Edge Device Discovery and Adjacency setup

   See draft-hasmit-otv-03 2.2.1.


3.2.2.  Control Plane Packet Encapsulation and Relay

   Any Jonit Device of the site is virtual link with the other Jonit
   Devices of the other sites.  Any Jonit Device should encapsulate the
   ISIS routing information of its site, and then relay it to the other
   Joint Devices of the other sites.

   There is no different between the virtual links and the physical
   links to the TRILL protocol.  The TRILL protocol calculates the



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   routing information among the whole TRILL domain.



4.  Data Plane

4.1.  Encapsulation

   The encapsulation format is TRILL frame encapsulated in UDP inside of
   IPv4 or IPv6.

   The format of the UDP IPv4 encapsulation 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Version|  IHL  |Type of Service|          Total Length         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Identification        |Flags|      Fragment Offset    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Time to Live | Protocol = 17 |         Header Checksum       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                Source-site TRILL Joint Device IP Address      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Destination-site TRILL Joint Device (or multicast) Address  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Source Port = xxxx        |         Dest Port = TBD       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           UDP length          |        UDP Checksum = 0       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |R|R|R|R|I|R|R|R|           Overlay ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Instance ID                          | Reserved      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Outer Ethernet Header                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
   |                      TRILL Header                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Inner Ethernet Header                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Ethernet Payload                           |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+







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   The format of the UDP IPv6 encapsulation 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Version| Traffic Class |           Flow Label                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Payload Length        | Next Header=17|   Hop Limit   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   +              Source-site TRILL Joint Device IPv6 Address      +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   +   Destination-site TRILL Joint Device (or multicast) Address  +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Source Port = xxxx      |       Dest Port = TBD         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           UDP Length          |        UDP Checksum           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |R|R|R|R|I|R|R|R|           Overlay ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Instance ID                          | Reserved      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Outer Ethernet Header                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
   |                        TRILL Header                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Inner Ethernet Header                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Ethernet Payload                        |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+








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4.2.  Forwarding Process

4.2.1.  Forwarding from an Internal Link to the Overlay

   The forwarding within a site is normal TRILL forwarding, so here only
   describes the forwarding from an Internal link to the Overlay Link,
   or vice versa.

   A Joint Device is a transit Rbridge from TRILL point of view.  When a
   TRILL packet is received from the internal interface, egress Nickname
   is used to lookup the Nickname table which will yield a next-hop IP
   address entry pointing to a remote Joint Device.  Then the packet is
   encapsulated with UDP/IP header and sent over the overlay interface
   to destination Joint Device at Layer-3 as a regular IP packet.

4.2.2.  Forwarding from the Overlay Link to an Internal Link

   When a packet is received on the overlay interface, it will be IP
   decapsulated to reveal the inner TRILL(including the outer MAC)
   header for forwarding.  The egress Nickname will used for forwarding,
   the forwarding action is same as a transit RBridge.

4.2.3.  Multicast Packet Flows

   To be added.

4.2.4.  Broadcast Packet Flows

   To be added.

4.2.5.  Mac Address Learning

   The TRILL edge devices learn remote MAC addresses(including the MAC
   addresses in other data centers) in data plane by hardware.  In most
   cases, the Joint device is like a transit RBridge, and doesn't learn
   end host's MAC addresses.  From DCI(Data Center Interconnect)
   perspective, the Joint Device is DCI device at the same time, so
   TRILL over WAN can relieve the pressure of MAC addresses table
   capability in DCI device.

4.2.6.  Multi-homing

   In the situation of multi-homing shown as Figure 3, all the Joint
   Devices can be active by the nature of TRILL.

   Figure 4 shows what the resulting forwarding tables would look like
   in the multi-homing example.




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          +---+ L1 +---+ IPA      --------       IPD +---+    +---+
          |S10|----| S1|-------- /        \ ---------|S4 |----|S21|
          +---+    +---+        /          \         +---+    +---+
                \/L2           |   IP Core  |              \/
                /\             |   Networ   |              /\
          +---+    +---+ IPB    \          /     IPC +---+    +---+
          |S11|----|S2 |-------- \        / ---------|S3 |----|S20|
          +---+    +---+          --------           +---+    +---+


                      Figure 3: Multi-homing Scenario




                           S1
                          +----------------------+
                          |Nickname   |Interface |
                          +----------------------+
                          |   S1      |   self   |
                          +----------------------+
                          |   S2      |   -      |
                          +----------------------+
                          |   S3      |   IPC    |
                          +----------------------+
                          |   S4      |   IPD    |
                          +----------------------+
                          |   S10     |   L1     |
                          +----------------------+
                          |   S11     |   L2     |
                          +----------------------+
                          |   S20     | IPC/IPD  |
                          +----------------------+
                          |   S21     | IPC/IPD  |
                          +----------------------+



                     Figure 4: Forwarding Table of S1


   In S1 device, the traffic destinated to S10 and S21 have two next
   hops, IPC and IPD.  In forwarding process, hashing of TRILL packet
   inner information will be used to determine which next hop IP address
   to use.  Thus, the ingress traffic will be load balanced between
   multiple Joint Devices within a site.





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5.  IANA Considerations

   IANA need to allocate the following UDP Ports for the TRILL IS-IS and
   Data channels:


          UDP Port           Protocol

           TBD              TRILL IS-IS Channel
           TBD              TRILL Data Channel



6.  Security Considerations

6.1.  Failure Separation

   To be added.


7.  Acknowledgements

   Much of the wording herein was adapted from draft-hasmit-otv-03.


8.  Normative References

   [I-D.hasmit-otv]
              Grover, H., Rao, D., Farinacci, D., and V. Moreno,
              "Overlay Transport Virtualization", draft-hasmit-otv-03
              (work in progress), July 2011.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6325]  Perlman, R., Eastlake, D., Dutt, D., Gai, S., and A.
              Ghanwani, "Routing Bridges (RBridges): Base Protocol
              Specification", RFC 6325, July 2011.

   [RFC6326]  Eastlake, D., Banerjee, A., Dutt, D., Perlman, R., and A.
              Ghanwani, "Transparent Interconnection of Lots of Links
              (TRILL) Use of IS-IS", RFC 6326, July 2011.

   [RFC6327]  Eastlake, D., Perlman, R., Ghanwani, A., Dutt, D., and V.
              Manral, "Routing Bridges (RBridges): Adjacency", RFC 6327,
              July 2011.





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Authors' Addresses

   Xiaolan Wan
   HangZhou H3C Co. Limited
   No. 2 ChuangYe Road, HaiDian District
   Beijing
   P.R. China

   Phone: +86 10 82774971
   Email: wxlan@h3c.com


   Xiaopeng Yang
   HangZhou H3C Co. Limited
   No. 2 ChuangYe Road, HaiDian District
   Beijing
   P.R. China

   Phone: +86 10 82774963
   Email: yxp@h3c.com


   Vishwas Manral
   Hewlett-Packard Co.
   19111 Pruneridge Ave.
   Cupertino, CA
   USA

   Email: vishwas.manral@hp.com


   Alvaro Retana
   Hewlett-Packard Co.
   2610 Wycliff Road
   Raleigh, NC
   USA

   Email: alvaro.retana@hp.com













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