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Versions: 00 01 02

BESS Workgroup                                                     T. Yu
Internet-Draft                                          January 15, 2019
Intended status: Experimental
Expires: July 19, 2019


                      EVPN Enhanced Mass Withdraw
                  draft-yu-bess-evpn-mass-withdraw-00

Abstract

   This document aims to define a enhanced mass withdraw process in case
   of multiple ES or vES fails.

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
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   This Internet-Draft will expire on July 19, 2019.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Specification of Requirements . . . . . . . . . . . . . . . .   2
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Requriments . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Solution Description  . . . . . . . . . . . . . . . . . . . .   3
   6.  EVPN Mass-Withdraw Community  . . . . . . . . . . . . . . . .   4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   EVPN [RFC7432] defines a mass withdraw mechanism to efficiently and
   quickly signal to remote PE nodes in case of a connection to ES
   fails.  But there are paticular scenarios that failure of multiple
   ESs can happen listed but not limited below:

   o  ES scenario: Failue of a line-card leads to failure of multiple
      ESs.

   o  vES scenario: Failure of physical port leads to failure of
      multiple vESs aggregating EVC.

   o  vES scenario: Failure of LAG leads to failure of multiple vESs
      aggregating EVC.

   o  vES scenario: Failure of multiple MPLS NNI ports leads to failure
      of LSP and multiple vESs aggregating PWs.

   o  vES scenario: Failure of EVC leading to failure of multiple vESs.

   o  vES scenario: Failure of PW leading to failure of multiple vESs.

   o  vES scenario: Failure of line-card leads to failure of multiple
      vESs.

   This document aims to introduce a solution improving convegence
   performance in case of failure on multiple ESs.

2.  Specification of Requirements

   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 [RFC2119].




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3.  Terminology

   EVPN: BGP MPLS-Based Ethernet VPN defined in [RFC7432]

   EVI: EVPN Instance

   EVPN VPWS: Refers to [RFC8214]

   vES: Virtual Ethernet Segment
   [I-D.ietf-bess-evpn-virtual-eth-segment]

   EVC: Ethernet Virtual Circuit

   PW: Pseudowire

4.  Requriments

   (R1a): The mass withdraw mechanism MUST handle both single-active and
   active-active multi-homed ES.

   (R1b): The mass withdraw mechanism MUST handle both single-active and
   active-active multi-homed vES.

   (R1c): The mass withdraw mechanism SHOULD handle a huge number of ES/
   vES.

   (R1d): The mass withdraw mechanism SHOULD handle failure scenarios
   mentioned in section 1.

   (R1e): The mass withdraw mechanism SHOULD allowing aggregating
   sequential ESI.

   (R1f): A suppresion mechanism is requried in case flapping occours
   leading to failure of large number of ES/vES

5.  Solution Description

   In order to reduce the number of ES/vES withdraw routes, the PE
   SHOULD aggregate ESI if the impacted ESI are sequential and send
   along with EVPN mass-withdraw community defined in section 6.  If the
   impacted ES/vES are nonsequential then multiple EVPN mass-withdraw
   communities can be sent along the flush message.

   To achieve a fast convergence time in case of multiple ES/vES fails,
   a sequential ES/vES helps.  This can be achieved via proper ES/vES
   auto-generating algorithm or proper planning.  An example is given
   below:




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   Assume type 0 ESI is used.  An ESI/vESI planning rule is:

   3 octs are used to identify device id

   4 octs are used to identify ifindex.  Ifindex uniquelly idenfies
   physical port, LAG or any logical ENNI port.

   3 octs are used to identify service id under each interface, if 0 it
   is used as ES, if not 0 it is used as vES.

   In case of port LAG or PW failure, an EVPN mass-withdraw community
   can be generated with all impacted vES with bit map.

   The auto-generating algorithm and planning rule on ES/vES is out of
   scope of current document.  Example given above is only used to
   explan the possibility of ESI aggregation.

   A timer SHOULD be started each time for each flushing.  Further
   failure during the timer SHOULD be suppressed.  A half-life based
   damping mechanism MAY be implemented.

6.  EVPN Mass-Withdraw Community

   A new EVPN BGP Extended Community called EVPN Mass-Withdraw Community
   is introduced.  This new extended community is a transitive extended
   community with the Type field of 0x06 (EVPN) and the Sub-Type of TBD.

               +-------------------------------------------+
               |  Type (0x06) / Sub-type (TBD) (2 octets)  |
               +-------------------------------------------+
               |  ESI  (10 octets)                         |
               +-------------------------------------------+
               |  Bitmap (10 octets)                       |
               +-------------------------------------------+

   Figure 1: EVPN Mass-Withdraw Community

7.  Security Considerations

   TBD

8.  IANA Considerations

   Sub-type for EVPN Mass-Withdraw Community to be allocated.







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9.  Normative References

   [I-D.ietf-bess-evpn-virtual-eth-segment]
              Sajassi, A., Brissette, P., Schell, R., Drake, J., and J.
              Rabadan, "EVPN Virtual Ethernet Segment", draft-ietf-bess-
              evpn-virtual-eth-segment-03 (work in progress), January
              2019.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [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, <https://www.rfc-editor.org/info/rfc7432>.

   [RFC8214]  Boutros, S., Sajassi, A., Salam, S., Drake, J., and J.
              Rabadan, "Virtual Private Wire Service Support in Ethernet
              VPN", RFC 8214, DOI 10.17487/RFC8214, August 2017,
              <https://www.rfc-editor.org/info/rfc8214>.

Author's Address

   Tianpeng Yu

   EMail: yutianpeng.ietf@gmail.com























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