[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03

BESS Workgroup                                           J. Rabadan, Ed.
Internet Draft                                              S. Sathappan
Intended status: Standards Track                              K. Nagaraj
                                                                   Nokia

                                                               M. Miyake
                                                              T. Matsuda
                                                                Softbank

Expires: July 19, 2018                                  January 15, 2018




                     PBB-EVPN ISID-based CMAC-Flush
               draft-snr-bess-pbb-evpn-isid-cmacflush-03

Abstract

   RFC7623 defines how Provider Backbone Bridging (PBB) can be combined
   with Ethernet VPN (EVPN) to deploy ELAN services in very large MPLS
   networks. RFC7623 also describes how Single-Active Multi-homing and
   per-ISID Load-Balancing can be provided to access devices and
   aggregation networks. In order to speed up the network convergence in
   case of failures on Single-Active Multi-Homed Ethernet Segments,
   RFC7623 defines a CMAC-Flush mechanism that works for different
   Ethernet Segment BMAC address allocation models. This document
   complements those CMAC-Flush procedures for cases in which no PBB-
   EVPN Ethernet Segments are defined (ESI 0) and an ISID-based CMAC-
   Flush granularity is desired.

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), 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/ietf/1id-abstracts.txt



Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018           [Page 1]


Internet-Draft       PBB-EVPN ISID-based CMAC-flush     January 15, 2018


   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   This Internet-Draft will expire on July 19, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (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. Problem Statement . . . . . . . . . . . . . . . . . . . . . . .  2
   2. Solution requirements . . . . . . . . . . . . . . . . . . . . .  4
   3. EVPN BGP Encoding for ISID-based CMAC-flush . . . . . . . . . .  5
   4. Solution description  . . . . . . . . . . . . . . . . . . . . .  6
     4.1 ISID-based CMAC-Flush activation procedures  . . . . . . . .  6
     4.2 CMAC-Flush generation  . . . . . . . . . . . . . . . . . . .  7
     4.3 CMAC-Flush process upon receiving a CMAC-Flush
         notification . . . . . . . . . . . . . . . . . . . . . . . .  7
   5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   6. Conventions used in this document . . . . . . . . . . . . . . .  8
   7. Security Considerations . . . . . . . . . . . . . . . . . . . .  9
   8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  9
   9. References  . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     9.1 Normative References . . . . . . . . . . . . . . . . . . . .  9
     9.2 Informative References . . . . . . . . . . . . . . . . . . .  9
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  9
   11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . .  9
   17. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 10




1. Problem Statement

   RFC7623 defines how Provider Backbone Bridging (PBB) can be combined



Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018           [Page 2]


Internet-Draft       PBB-EVPN ISID-based CMAC-flush     January 15, 2018


   with Ethernet VPN (EVPN) to deploy ELAN services in very large MPLS
   networks. RFC7623 also describes how Single-Active Multi-homing and
   per-ISID Load-Balancing can be provided to access devices and
   aggregation networks. When Access Ethernet/MPLS Networks exists,
   [vES] describes how virtual ES can be associated to a group of
   Ethernet Virtual Circuits (EVCs) or even Pseudowires (PWs). In order
   to speed up the network convergence in case of failures on Single-
   Active Multi-Homed Ethernet Segments, RFC7623 defines a CMAC-Flush
   mechanism that works for different Ethernet Segment BMAC address
   allocation models.

   In some cases, the administrative entities that manage the access
   devices or aggregation networks, don't demand Multi-Homing Ethernet
   Segments (ES) from the PBB-EVPN provider, but simply multiple single-
   homed ES. If that is the case, the PBB-EVPN network is no longer
   aware of the redundancy offered by the access administrative entity.
   Figure 1 shows an example where the PBB-EVPN network provides four
   different Attachment Circuits (ACs) for ISID1, with those ACs not
   being part of any ES or vES (therefore they are referred to as null
   vES).

                        <--PBB-EVPN Network--->

          ISID1     vES +-----+         +-----+
          +----+    null| PE1 +---------+ PE3 |vES null
          |CE1 +--------+ BM1 |         | BM3 | +---------+
          +-+--+     act|     |         |     |=====      |
            |   G.8032  +-+---+         +---+-+ |   \act  | ISID1
            |   Access    |                 |   |    \  +-+--+
            |    Ring     |     IP/MPLS     |   |     ==|CE3 |
            |             |                 |   |    /  +-+--+
            |stb    vES +-+---+         +---+-+ |   /stb  |
          +-+--+    null| PE2 |         | PE4 +-----      |
          |CE2 +--------+ BM2 |         | BM4 | +---------+
          +----+     act|     +---------+     |vES null
          ISID1         +-----+         +-----+ <-MPLS Ag->
                                                  Network

               Figure 1 PBB-EVPN and non-ES based redundancy

   In the example in Figure 1, CE1 and CE2 provide redundant
   connectivity for ISID1 through the use of G.8032 Ethernet Ring
   Protection Switching. CE3 provides redundant active-standby PW
   connectivity for ISID1. In the two cases the ACs are connected to
   null ES, hence the PEs will keep their ACs active and the CEs will be
   responsible for the per-ISID load balancing while avoiding loops.

   For instance, CE2 will block its link to CE1 and CE3 will block its



Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018           [Page 3]


Internet-Draft       PBB-EVPN ISID-based CMAC-flush     January 15, 2018


   forwarding path to PE4. In this situation, a failure in one of the
   redundant ACs will make the CEs to start using their redundant paths,
   however those failures will not trigger any CMAC-Flush procedures in
   the PEs. For example, if the active PW from CE3 fails, PE3 will not
   issue any CMAC-Flush message and therefore the remote PEs will
   continue pointing at PE3's BMAC to reach CE3's CMACs, until the CMACs
   age out in the ISID1 FDBs.

   RFC7623 provides a CMAC-Flush solution based on a shared BMAC update
   along with the MAC Mobility extended community where the sequence
   number is incremented. However, while that procedure could be used in
   the example of Figure 1, it would result in unnecessary flushing of
   unaffected ISIDs on the remote PEs, and subsequent flooding.

   This document describes an extension of the RFC7623 CMAC-Flush
   procedures, so that in the above failure example, PE3 can trigger a
   CMAC-Flush notification that makes PE1, PE2 and PE4 flush all the
   CMACs associated to PE3's BMAC and (only) ISID1. This new CMAC-Flush
   procedure explained in this document will be referred to as "PBB-EVPN
   ISID-based CMAC-Flush" and can be used in PBB-EVPN networks with null
   or non-null (virtual) Ethernet Segments.


2. Solution requirements

   The following requirements must be met by the CMAC-Flush solution
   described in this document:

   a) The solution MUST solve black-hole scenarios in case of failures
      on null ES ACs (Attachment Circuits not associated to ES, that is,
      ESI=0) when the access device/network is responsible for the
      redundancy.

   b) This extension SHOULD work with Single-Active non-null ES and
      virtual ES, irrespective of the PE BMAC address assignment
      (dedicated per-ES BMAC or shared BMAC).

   c) In case of failure on the egress PE, the solution MUST provide a
      CMAC-Flush notification at BMAC AND ISID granularity level.

   d) The solution MUST provide a reliable CMAC-Flush notification in
      PBB-EVPN networks that use Route-Reflectors (RRs).

   e) The solution MUST coexist in RFC7623-compliant networks where
      there are systems not supporting this extension.

   f) The solution SHOULD be enabled/disabled by an administrative
      option on a per-PE and per-ISID basis.



Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018           [Page 4]


Internet-Draft       PBB-EVPN ISID-based CMAC-flush     January 15, 2018


3. EVPN BGP Encoding for ISID-based CMAC-flush

   The solution does not use any new BGP attributes but reuses the MAC
   Mobility extended community as an indication of CMAC-Flush (as in
   RFC7623) and encodes the ISID in the Ethernet Tag field of the MAC/IP
   route. As a reference, Figure 2 shows the MAC Mobility extended
   community and the MAC/IP route that are used in this document as a
   CMAC-Flush notification.


   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Type=0x06     | Sub-Type=0x03 |   Flags       |   Reserved=0  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Sequence Number                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


               +---------------------------------------+
               |  RD                                   |
               +---------------------------------------+
               |  ESI = 0                              |
               +---------------------------------------+
               |  Ethernet Tag ID = ISID               |
               +---------------------------------------+
               |  MAC Address Length = 48              |
               +---------------------------------------+
               |  BMAC Address                         |
               +---------------------------------------+
               |  IP Address Length = 0                |
               +---------------------------------------+
               |  MPLS Label1                          |
               +---------------------------------------+

        Figure 2 CMAC-Flush notification encoding: BMAC/ISID route

   Where:

   o The route's RD and RT are the ones corresponding to its EVI.
     Alternatively to the EVI's RT, the route MAY be tagged with an RT
     auto-derived from the Ethernet Tag (ISID) instead. RFC7623
     describes how the RT can be derived from the ISID.

   o The Ethernet Tag encodes the ISID for which the PE that receives
     the route must flush the CMACs upon reception of the route.

   o The MAC address field encodes the BMAC Address for which the PE
     that receives the route must flush the CMACs upon reception of the



Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018           [Page 5]


Internet-Draft       PBB-EVPN ISID-based CMAC-flush     January 15, 2018


     route.

   o The MAC Mobility extended community is used as in RFC7623, where a
     delta in the sequence number between two updates for the same
     BMAC/ISID will be interpreted as a CMAC-flush notification for the
     corresponding BMAC and ISID.

   All the other fields are set and used as defined in RFC7623. This
   document will refer to this route as the BMAC/ISID route, as opposed
   to the RFC7623 BMAC/0 route (BMAC route sent with Ethernet Tag = 0).

   Note that this BMAC/ISID route will be accepted and reflected by any
   RFC7432-compliant RR, since no new attributes or values are used. A
   PE receiving the route will process the received BMAC/ISID update
   only in case of supporting the procedures described in this
   document.


4. Solution description

   Figure 1 will be used in the description of the solution. CE1, CE2
   and CE3 are connected to ACs associated to ISID1, where no (Multi-
   Homed) Ethernet Segments have been enabled. All the ACs are
   operationally active and ready to forward frames.

   Enabling or disabling ISID-based CMAC-Flush SHOULD be an
   administrative choice on the system that MAY be configured per ISID
   (I-Component). When enabled on a PE:

   a) The PE will be able to generate BMAC/ISID routes as CMAC-Flush
      notifications for the remote PEs.

   b) The PE will be able to process BMAC/ISID routes received from
      remote PEs.

   When ISID-based CMAC-Flush is disabled, the PE will follow the
   RFC7623 procedures for CMAC-flush.

   These new CMAC-flush procedures are described in sections 4.1, 4.2
   and 4.3 respectively:

   o ISID-based CMAC-flush activation
   o CMAC-flush notification generation upon AC failures
   o CMAC-flush process upon receiving a CMAC-Flush notification


4.1 ISID-based CMAC-Flush activation procedures




Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018           [Page 6]


Internet-Draft       PBB-EVPN ISID-based CMAC-flush     January 15, 2018


   The following behavior MUST be followed by the PBB-EVPN PEs (see
   Figure 1):

   o As in RFC7623, each PE has previously advertised a shared BMAC in a
     BMAC/0 route (BM1, BM2, BM3 and BM4 respectively). This is the BMAC
     that each PE will use as BMAC SA (Source Address) when
     encapsulating the frames received on any local single-homed AC.
     Each PE will import the received BMAC/0 routes from the remote PEs
     and will install the BMACs in its B-component MAC-VRF. For
     instance, PE1 will advertise BM1/0 and will install BM2, BM3 and
     BM4 in its MAC-VRF.

   o Assuming ISID-based CMAC-Flush is activated for ISID 1, the PEs
     will advertise the shared BMAC with ISID 1 encoded in the Ethernet
     Tag. That is, PE1 will advertise BM1/1 and will receive BM2/1,
     BM3/1 and BM4/1. The receiving PEs MUST use these BMAC/ISID routes
     only for CMAC-Flush procedures and they MUST NOT be used to
     add/withdraw any BMAC entry in the MAC-VRFs. As per RFC7623, only
     BMAC/0 routes can be used to add/withdraw BMACs in the MAC-VRFs.

   o The above procedure MAY also be used for dedicated BMACs.

4.2 CMAC-Flush generation

   If, for instance, there is a failure on PE1's AC, PE1 will generate
   an update including BM1/1 along with the MAC Mobility extended
   community where the Sequence Number has been incremented. The
   reception of the BM1/1 with a delta in the sequence number will
   trigger the CMAC-Flush procedures on the receiving PEs.

   o An AC going operationally down MUST generate a BMAC/ISID with a
     higher Sequence Number. If the AC going down makes the entire local
     ISID go operationally down, the PE will withdraw the BMAC/ISID
     route for the ISID.

   o An AC going operationally up SHOULD NOT generate any BMAC/ISID
     update, unless it activates its corresponding ISID, in which case
     the PE will advertise the BMAC/ISID route.

   o An AC receiving a CMAC-Flush notification from the access network,
     e.g. by G.8032, MAY propagate it to the remote PEs by generating a
     BMAC/ISID update with higher Sequence Number.


4.3 CMAC-Flush process upon receiving a CMAC-Flush notification

   A PE receiving a CMAC-Flush notification will follow these
   procedures:



Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018           [Page 7]


Internet-Draft       PBB-EVPN ISID-based CMAC-flush     January 15, 2018


   o A received BMAC/ISID route (with non-zero ISID) MUST NOT add/remove
     any BMAC to/from the MAC-VRF.

   o An update of a previously received BMAC/ISID route with a delta
     Sequence Number, MUST flush all the CMACs associated to that ISID
     and BMAC. CMACs associated to the same ISID but different BMAC MUST
     NOT be flushed.

   o A received BMAC/ISID withdraw (with non-zero ISID) MUST flush all
     the CMACs associated to that BMAC and ISID.

   Note that the CMAC-Flush procedures described in RFC7623 for BMAC/0
   routes are still valid and a PE receiving RFC7623 CMAC-flush
   notification messages MUST observe the behavior specified in RFC7623.


5. Conclusions

   The ISID-based CMAC-Flush solution described in this document has the
   following benefits:

   a) The solution solves black-hole scenarios in case of failures on
      null ES ACs, since the CMAC-flush procedures are independent of
      the Ethernet Segment definition.

   b) This extension can also be used with Single-Active non-null ES and
      virtual ES, irrespective of the PE BMAC address assignment
      (dedicated per-ES BMAC or shared BMAC).

   c) It provides a CMAC-Flush notification at BMAC AND ISID granularity
      level, therefore flushing a minimum number of CMACs and reducing
      the amount of flooding in the network.

   d) It provides a reliable CMAC-Flush notification in PBB-EVPN
      networks that use RRs. RRs will propagate the CMAC-flush
      notifications for all the affected ISIDs and irrespective of the
      order in which the notifications make it to the RR.

   e) The solution can coexist in a network with systems supporting or
      not supporting the CMAC-flush extensions.


6. Conventions used in this document

   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].




Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018           [Page 8]


Internet-Draft       PBB-EVPN ISID-based CMAC-flush     January 15, 2018


   In this document, these words will appear with that interpretation
   only when in ALL CAPS. Lower case uses of these words are not to be
   interpreted as carrying RFC-2119 significance.

   In this document, the characters ">>" preceding an indented line(s)
   indicates a compliance requirement statement using the key words
   listed above. This convention aids reviewers in quickly identifying
   or finding the explicit compliance requirements of this RFC.

7. Security Considerations

   This section will be added in future versions.

8. IANA Considerations


9. References

9.1 Normative References



   [RFC7432]Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
   Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet
   VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, <http://www.rfc-
   editor.org/info/rfc7432>.


   [RFC7623]Sajassi, A., Ed., Salam, S., Bitar, N., Isaac, A., and W.
   Henderickx, "Provider Backbone Bridging Combined with Ethernet VPN
   (PBB-EVPN)", RFC 7623, September 2015, <http://www.rfc-
   editor.org/info/rfc7623>.


9.2 Informative References

   [vES] Sajassi et al. "EVPN Virtual Ethernet Segment", draft-sajassi-
   bess-evpn-virtual-eth-segment-01, work-in-progress, July 6, 2015.


10. Acknowledgments

   The authors want to thank Vinod Prabhu, Sriram Venkateswaran, Laxmi
   Padakanti, Ranganathan Boovaraghavan for their review and
   contributions.

11. Contributors




Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018           [Page 9]


Internet-Draft       PBB-EVPN ISID-based CMAC-flush     January 15, 2018


17. Authors' Addresses

   Jorge Rabadan
   Nokia
   777 E. Middlefield Road
   Mountain View, CA 94043 USA
   Email: jorge.rabadan@nokia.com

   Senthil Sathappan
   Nokia
   701 E. Middlefield Road
   Mountain View, CA 94043 USA
   Email: senthil.sathappan@nokia.com

   Kiran Nagaraj
   Nokia
   701 E. Middlefield Road
   Mountain View, CA 94043 USA
   Email: kiran.nagaraj@nokia.com

   Masahiro Miyake
   Softbank
   Email: masahiro.miyake@g.softbank.co.jp

   Taku Matsuda
   Softbank
   Email: taku.matsuda@g.softbank.co.jp
























Sathappan,Nagaraj,Rabadan et al.Expires July 19, 2018          [Page 10]


Html markup produced by rfcmarkup 1.126, available from https://tools.ietf.org/tools/rfcmarkup/