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Versions: (draft-sajassi-l2vpn-evpn-vpls-integration) 00 draft-ietf-bess-evpn-vpls-seamless-integ

INTERNET-DRAFT                                               Ali Sajassi
Intended Status: Standard Track                              Samer Salam
                                                                   Cisco

                                                          Nick Del Regno
                                                                 Verizon

                                                           Jorge Rabadan
                                                          Alcatel-Lucent

Expires: April 27, 2015                                 October 27, 2014


            (PBB-)EVPN Seamless Integration with (PBB-)VPLS
             draft-sajassi-bess-evpn-vpls-seamless-integ-00


Abstract

   This draft discusses the backward compatibility of the (PBB-)EVPN
   solution with (PBB-)VPLS and provides mechanisms for seamless
   integration of the two technologies in the same MPLS/IP network on a
   per-VPN-instance basis.


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
   Task Force (IETF), its areas, and its working groups.  Note that
   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
   http://www.ietf.org/shadow.html


Copyright and License Notice



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   Copyright (c) 2013 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
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   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  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3 PBB-VPLS Integration with PBB-EVPN . . . . . . . . . . . . . . .  4
     3.1 Capability Discovery . . . . . . . . . . . . . . . . . . . .  4
     3.2 Forwarding Setup and Unicast Operation . . . . . . . . . . .  5
     3.3 Multicast Operation  . . . . . . . . . . . . . . . . . . . .  6
       3.3.1 Ingress Replication  . . . . . . . . . . . . . . . . . .  6
       3.3.2 LSM  . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   4 VPLS Integration with EVPN . . . . . . . . . . . . . . . . . . .  7
     4.1 Capability Discovery . . . . . . . . . . . . . . . . . . . .  7
     4.2 Forwarding Setup and Unicast Operation . . . . . . . . . . .  7
     4.3 Multicast Operation  . . . . . . . . . . . . . . . . . . . .  7
       4.3.1 Ingress Replication  . . . . . . . . . . . . . . . . . .  7
       4.3.2 LSM  . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   5 VPLS Integration with PBB-EVPN . . . . . . . . . . . . . . . . .  7
     5.1 Capability Discovery . . . . . . . . . . . . . . . . . . . .  7
     5.2 Forwarding Setup and Unicast Operation . . . . . . . . . . .  7
     5.3 Multicast Operation  . . . . . . . . . . . . . . . . . . . .  8
       5.3.1 Ingress Replication  . . . . . . . . . . . . . . . . . .  8
       5.3.2 LSM  . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   6 Solution Advantages  . . . . . . . . . . . . . . . . . . . . . .  8
   7 Security Considerations  . . . . . . . . . . . . . . . . . . . .  8
   8  IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  8
   9  References  . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     9.1  Normative References  . . . . . . . . . . . . . . . . . . .  8
     9.2  Informative References  . . . . . . . . . . . . . . . . . .  9
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  9






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1  Introduction

   VPLS and PBB-VPLS are widely-deployed L2VPN technologies. Many SPs
   who are looking at adopting EVPN and PBB-EVPN want to preserve their
   investment in the (PBB-)VPLS networks. Hence, it is required to
   provide mechanisms by which (PBB-)EVPN technology can be introduced
   into existing L2VPN networks without requiring a fork-lift upgrade.
   This document discusses mechanisms for the seamless integration of
   the two technologies in the same MPLS/IP network.

                            VPLS PE
                             +---+
                             |PE1|
                             +---+
                               /
        EVPN/VPLS PE  +---------------+   EVPN/VPLS PE
             +---+    |               |   +---+
             |PE4|----|    MPLS/IP    |---|PE5|
             +---+    |     Core      |   +---+
                      |               |
                      +---------------+
                        /        \
                     +---+     +---+
                     |PE2|     |PE3|
                     +---+     +---+
                   VPLS PE     VPLS PE

     Figure 1: Seamless Integration of (PBB-)EVPN PEs & (PBB-)VPLS

   Section 2 provides the details of the requirements. Section 3
   discusses PBB-VPLS integration with PBB-EVPN. Section 4 discusses the
   integration of VPLS and EVPN. Section 5 discusses the integration of
   VPLS and PBB-EVPN, and finally Section 6 discusses the solution
   advantages.

   It is worth noting that the scenario where PBB-VPLS is integrated
   with EVPN, is for future study and upon market validation. The reason
   for that is that deployments which employ PBB-VPLS typically require
   PBB encapsulation for various reasons. Hence, it is expected that for
   those deployments the evolution path would be from PBB-VPLS towards
   PBB-EVPN, rather than EVPN.

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 [KEYWORDS].




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2.  Requirements

   Following are the key requirements for backward compatibility between
   (PBB-)EVPN and (PBB-)VPLS:

   1. The solution MUST allow for staged migration towards (PBB-)EVPN on
   a site-by-site basis per VPN instance - e.g., new EVPN sites to be
   provisioned on (PBB-)EVPN PEs.

   2. The solution MUST require no changes to existing VPLS or PBB-VPLS
   PEs, not even a software upgrade.

   3. The solution MUST allow for the coexistence of PE nodes running
   (PBB-)EVPN and (PBB-)VPLS for the same VPN instance and single-homed
   segments.

   4. The solution MUST support single-active redundancy of multi-homed
   networks and multi-homed devices for (PBB-)EVPN PEs.

   5. In case of single-active redundancy, the participant VPN instances
   MAY span across both (PBB-)EVPN PEs and (PBB-)VPLS PEs as long as
   single-active redundancy is employed by (PBB-)EVPN PEs. In case of an
   ES link failure, the (PBB-)EVPN PEs will send a BGP mass-withdraw to
   the EVPN peers OR MAC advertisement with MAC Mobility extended
   community for PBB-EVPN AND an LDP MAC withdrawal to the VPLS peers.

   6. The solution SHOULD support all-active redundancy of multi-homed
   networks and multi-homed devices for (PBB-)EVPN PEs.

   7. In case of all-active redundancy, the participant VPN instances
   SHOULD be confined to (PBB-)EVPN PEs only.


   These requirements collectively allow for the seamless insertion of
   the (PBB-)EVPN technology into brown-field (PBB-)VPLS deployments.

3 PBB-VPLS Integration with PBB-EVPN

   In order to support seamless integration with (PBB-)VPLS, the (PBB-
   )EVPN PEs MUST support EVPN BGP routes (EVPN SAFI) and SHOULD support
   VPLS AD route (VPLS SAFI). All the logic for the integration will
   reside on the (PBB-)EVPN PEs side. However, if a VPLS instance is
   setup without the use of BGP auto-discovery, it is still possible
   (but cumbersome) for (PBB-)EVPN PEs to integrate into that VPLS
   instance.

3.1 Capability Discovery




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   The (PBB-)EVPN PEs must advertise both the BGP VPLS auto-discovery
   (AD) route as well as the BGP EVPN Inclusive Multicast route for a
   given VPN instance. The (PBB-)VPLS PEs only advertise the BGP VPLS AD
   route, per current standard procedures specified in [RFC4761] and
   [RFC6074]. The operator may decide to use the same BGP RT for both
   (PBB-)EVPN and (PBB-)VPLS. In this case, when a (PBB-)VPLS PE
   receives the EVPN Inclusive Multicast route, it will ignore it on the
   basis that it belongs to an unknown SAFI. However, the operator may
   use two RTs (one for (PBB-)VPLS and another for (PBB-)EVPN) and
   employ RT-constraint in order to prevent EVPN BGP routes from
   reaching the (PBB-)VPLS PEs. This provides an optimization in case
   required by the scale of the network.

   When a (PBB-)EVPN PE receives both a VPLS AD route as well as an EVPN
   Inclusive Multicast route from a given remote PE for the same VPN
   instance, it MUST give preference to the EVPN route for the purpose
   of discovery. This ensures that, at the end of the route exchanges,
   all (PBB-)EVPN capable PEs discover other (PBB-)EVPN capable PEs as
   well as the (PBB-)VPLS-only PEs for that VPN instance. Furthermore,
   all the (PBB-)VPLS-only PEs would discover the (PBB-)EVPN PEs as if
   they were standard (PBB-)VPLS nodes. In other words, when the
   discovery phase is complete, the (PBB-)EVPN PEs would have discovered
   all the PEs in the VPN instance, and their associated capability:
   (PBB-)EVPN or VPLS-only. Whereas the (PBB-)VPLS PEs would have
   discovered all the PEs in the VPN instance, as if they were all VPLS-
   only nodes.


3.2 Forwarding Setup and Unicast Operation

   The procedures for forwarding setup and unicast operation on the
   (PBB-)VPLS PE are per [RFC4447] and [PBB-VPLS].

   The procedures for forwarding state setup and unicast operation on
   the (PBB-)EVPN PE are as follows:

   - The (PBB-)EVPN PE must establish a pseudowire to a remote PE from
   which it has received only a VPLS AD route, for the VPN instance in
   question, and set up the label stack corresponding to the pseudowire
   FEC. This PW is between B-components of PBB-EVPN PE and PBB-VPLS PE
   per section 4 of  [PBB-VPLS-PE-MODEL].

   - The (PBB-)EVPN PE must set up the label stack corresponding to the
   MP2P (PBB-)VPN unicast FEC to any remote PE that has advertised EVPN
   AD route.

   - If a (PBB-)EVPN PE receives a VPLS AD route followed by an EVPN AD
   route from the same PE and a pseudowire is setup to that PE, then the



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   (PBB-)EVPN MUST bring that pseudowire operationally down.

   - If a (PBB-)EVPN PE receives an EVPN AD route followed by a VPLS AD
   route from the same PE, then the (PBB-)EVPN PE will setup the
   pseudowire but MUST keep it operationally down.

   When the (PBB-)EVPN PE receives traffic over the pseudowires, it
   learns the associated MAC addresses in the data-plane. This is
   analogous to dynamic learning in IEEE bridges. If the PW belongs to
   the same split-horizon group as the EVPN mesh, then the MAC addresses
   learnt and associated to the PW will NOT be advertised in the control
   plane to any remote (PBB-)EVPN PE. The (PBB-)EVPN PE learns MAC
   addresses in the control plane, via the EVPN MAC Advertisement routes
   sent by remote (PBB-)EVPN PEs, and updates its MAC forwarding table
   accordingly. This is analogous to static learning in IEEE bridges. In
   PBB-EVPN, a given B-MAC address can be learnt either over the BGP
   control-plane from a remote PBB-EVPN PE, or in the data-plane over a
   pseudowire from a remote PBB-VPLS PE. There is no mobility associated
   with B-MAC addresses in this context. Hence, when the same B-MAC
   address shows up behind both a remote PBB-VPLS PE as well as a PBB-
   EVPN PE, the local PE can deduce that there is an anomaly in the
   network.

3.3 Multicast Operation

3.3.1 Ingress Replication The procedures for multicast operation on the
   (PBB-)VPLS PE, using ingress replication, are per [RFC4761],
   [RFC4762], and [PBB-VPLS].

   The procedures for multicast operation on the PBB-EVPN PE, for
   ingress replication, are as follows:

   - The PBB-EVPN PE builds a replication sub-list per I-SID to all the
   remote PBB-EVPN PEs in a given VPN instance, as a result of the
   exchange of the EVPN Inclusive multicast routes, as described in
   [PBB-EVPN]. This will be referred to as sub-list A. It comprises MP2P
   tunnels used for delivering PBB-EVPN BUM traffic [EVPN].

   - The PBB-EVPN PE builds a replication sub-list per VPN instance to
   all the remote PBB-VPLS PEs , as a result of the exchange of the VPLS
   AD routes. This will be referred to as sub-list B. It comprises
   pseudowires from the PBB-EVPN PE in question to all the remote PBB-
   VPLS PEs in the same VPN instance.

   - The PBB-EVPN PE may further prune sub-list B, on a per I-SID basis,
   if [MMRP] is run over the PBB-VPLS network. This will be referred to
   as sub-list C. This list comprises a pruned set of the pseudowires in
   sub-list B.



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   The replication list, maintained per I-SID, on a given PBB-EVPN PE
   will be the union of sub-list A and sub-list B if [MMRP] is NOT used,
   and the union of sub-list A and sub-list C if [MMRP] is used. Note
   that the PE must enable split-horizon over all the entries in the
   replication list, across both pseudowires and MP2P tunnels.

3.3.2 LSM Will be covered in a future revision of this document.


4 VPLS Integration with EVPN

4.1 Capability Discovery

   The procedures for capability discovery are per Section 3.1 above.

4.2 Forwarding Setup and Unicast Operation

   The operation here is largely similar to that of PBB-EVPN integration
   with PBB-VPLS, with the exception of the need to handle MAC mobility,
   the details of which will be covered in a future revision of this
   document.

4.3 Multicast Operation

4.3.1 Ingress Replication

   The operation is per the procedures of Section 3.3.1 above for the
   scenario WITHOUT [MMRP]. The replication list is maintained per VPN
   instance, rather than per I-SID.

4.3.2 LSM Will be covered in a future revision of this document.

5 VPLS Integration with PBB-EVPN

5.1 Capability Discovery

   The procedures for capability discovery are per Section 3.1 above.

5.2 Forwarding Setup and Unicast Operation

   The operation here is largely similar to that of PBB-EVPN integration
   with PBB-VPLS, with a few exceptions listed below:

   - When a PW is setup between a PBB-EVPN PE and a VPLS PE, it gets
   setup between the I-component of PBB-EVPN PE and the bridge component
   of VPLS PE.

   - The MAC mobility needs to be handled. The details of which will be



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   covered in a future revision of this document.



5.3 Multicast Operation

5.3.1 Ingress Replication

   The operation is per the procedures of Section 3.3.1 above for the
   scenario WITHOUT [MMRP]. The replication list is maintained per I-SID
   on the PBB-EVPN PEs and per VPN instance on the VPLS PEs.

5.3.2 LSM Will be covered in a future revision of this document.


6 Solution Advantages

   The solution for seamless integration of (PBB-)EVPN with (PBB-)VPLS
   has the following advantages:

   - When ingress replication is used for multi-destination traffic
   delivery, the solution reduces the scope of [MMRP] (which is a soft-
   state protocol) to only that of existing VPLS PEs, and uses the more
   robust BGP-based mechanism for multicast pruning among new EVPN PEs.

   - It is completely backward compatible.

   - New PEs can leverage the extensive multi-homing mechanisms and
   provisioning simplifications of PBB-EVPN:
      1. Auto-sensing of MHN / MHD
      2. Auto-discovery of redundancy group
      3.Auto-provisioning of DF election and VLAN carving

7 Security Considerations

   No new security considerations beyond those for VPLS and EVPN.


8  IANA Considerations

   This document has no actions for IANA.


9  References

9.1  Normative References

   [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate



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              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4448]  Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron,
              "Encapsulation Methods for Transport of Ethernet over MPLS
              Networks", RFC 4448, April 2006.


   [RFC4447] Martini, et al., "Pseudowire Setup and Maintenance using
              the Label Distribution Protocol", draft-ietf-pwe3-
              rfc4447bis-02.txt, October 2013.

   [EVPN] Sajassi et al., "BGP MPLS Based Ethernet VPN", draft-ietf-
              l2vpn-evpn-04.txt, work in progress, July, 2013.

   [PBB-EVPN] Sajassi et al., "PBB-EVPN", draft-ietf-l2vpn-pbb-evpn-
              05.txt, work in progress, October, 2013.


9.2  Informative References


   [MMRP] Clause 10 of "IEEE Standard for Local and metropolitan area
   networks - Media Access Control (MAC) Bridges and Virtual Bridged
   Local Area Networks", IEEE Std 802.1Q, 2013.

   [PBB-VPLS-PE-MODEL] Balus, F., Sajassi, S., Bitar, N., "Extensions to
   VPLS PE model for Provider Backbone Bridging", RFC xxxx, June 2013.

   [PBB-VPLS] Sajassi, et al., "VPLS Interoperability with Provider
   Backbone Bridges", draft-ietf-l2vpn-pbb-vpls-interop-05.txt, work in
   progress, October, 2013.


Authors' Addresses


   Ali Sajassi
   Cisco
   Email: sajassi@cisco.com


   Samer Salam
   Cisco
   595 Burrard Street, Suite 2123
   Vancouver, BC V7X 1J1, Canada
   Email: ssalam@cisco.com





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   Nick Del Regno
   Verizon
   400 International Pkwy
   Richardson, TX  75089, US
   Email: nick.delregno@verizon.com


   Jorge Rabadan
   Alcatel-Lucent
   400 International Pkwy
   Richardson, TX  75089, US
   Email: jorge.rabadan@alcatel-lucent.com







































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