Propagation of IPv6 Neighbor Advertisement Flags in EVPN
draft-ietf-bess-evpn-na-flags-00

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





Expires: April 3, 2018                                September 30, 2017



        Propagation of IPv6 Neighbor Advertisement Flags in EVPN
                    draft-ietf-bess-evpn-na-flags-00


Abstract

   The MAC/IP Advertisement route specified in [RFC7432] can optionally
   carry IPv4 and IPv6 addresses associated with a MAC address. Remote
   PEs can use this information to reply locally (act as proxy) to IPv4
   ARP requests and IPv6 Neighbor Solicitation messages and
   reduce/suppress the flooding produced by the Address Resolution
   procedure. However, if the Neighbor information is learnt via EVPN,
   the PE would not know if a particular IPv6->MAC pair belongs to a
   host, a router or a host with an anycast address as this information
   is not carried in the MAC/IP route advertisements. This document
   proposes an OPTIONAL advertisement of the Flags defined in [RFC4861]
   along with the EVPN MAC/IP Advertisement routes, so that an EVPN PE
   implementing a proxy-ND function can reply to Neighbor Solicitations
   with the correct Flag information in Neighbor Advertisements.



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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   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents




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Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. The EVPN Neighbor Discovery (ND) Extended Community . . . . . .  3
   3. Use of the EVPN ND Extended Community . . . . . . . . . . . . .  4
   4. Conventions used in this document . . . . . . . . . . . . . . .  4
   5. Security Considerations . . . . . . . . . . . . . . . . . . . .  5
   6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  5
   7. References  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     7.1. Normative References  . . . . . . . . . . . . . . . . . . .  5
     7.2. Informative References  . . . . . . . . . . . . . . . . . .  5
   8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . .  5
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  5











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1. Introduction

   The MAC/IP Advertisement route specified in [RFC7432] can optionally
   carry IPv4 and IPv6 addresses associated with a MAC address. Remote
   PEs can use this information to reply locally (act as proxy) to IPv4
   ARP requests and IPv6 Neighbor Solicitation messages and
   reduce/suppress the flooding produced by the Address Resolution
   procedure. However, if the Neighbor information is learned via EVPN,
   the PE would not know if a particular IPv6->MAC pair belongs to a
   host or a router as this information is not carried in the MAC/IP
   route advertisements.

   This document proposes the OPTIONAL advertisement of the Flags
   defined in [RFC4861] along with the EVPN MAC/IP Advertisement routes,
   so that an EVPN PE implementing a proxy-ND function can issue
   Neighbor Advertisement messages conveying the correct Flag
   information.

   The Flags are carried in the Neighbor Discovery (ND) EVPN Extended
   Community, as described in the following sections.


2. The EVPN Neighbor Discovery (ND) Extended Community

   This document defines a new EVPN Extended Community with a Type field
   value of 0x06 and a Sub-Type TBD. It MAY be advertised along with
   EVPN MAC/IP Advertisement routes that carry an IPv6 address.

     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= TBD |Reserved=0 |O|R| Reserved=0    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       Reserved=0                              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The following Flags are defined in the third octet of the Extended
   Community:

   R - Router flag.

   The low-order bit of the third octet is defined as the "Router flag".
   When set, the R-bit indicates that the IPv6->MAC pair advertised
   along with the MAC/IP Advertisement route belongs to a router. If the
   R-bit is zero, the IPv6-MAC pair belongs to a "host". The receiving
   PE implementing the proxy-ND function will use this information in
   Neighbor Advertisement messages for the associated IPv6 address.




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   O - Override flag

   The second bit of the third octet is defined as the "Override flag".
   An egress PE will normally advertise IPv6->MAC pairs with the O-bit
   set, and only when IPv6 "anycast" is enabled in the EVI, the PE will
   send an IPv6->MAC pair with the O-bit = 0. The ingress PE will
   install the proxy-ND entry with the received O-bit and will use this
   information when replying to a Neighbor Solicitation for the IPv6
   address.

3. Use of the EVPN ND Extended Community

   An EVPN PE supporting a proxy-ND function and implementing the
   propagation of the Neighbor Advertisement Flags will follow this
   procedure:

   a) Transmission of the EVPN ND Extended Community

      A PE may learn the IPv6->MAC pair and its associated ND Flags in
      the management plane or snooping Neighbor Advertisement messages
      coming from the CE. Either way, the PE SHOULD send a MAC/IP
      Advertisement route including the learned IPv6->MAC pair and MAY
      send the ND Extended Community carrying its associated "R" and "O"
      Flags. This new Extended Community does not have any impact on the
      rest of the procedures described in [RFC7432], including the
      advertisement of the MAC Mobility Extended Community along with
      the MAC/IP Advertisement route.

   b) Reception of the EVPN ND Extended Community

      In addition to the procedures specified in [RFC7432] a PE
      receiving a MAC/IP Advertisement route containing an IPv6 address
      and the ND Extended Community SHOULD add the R and O Flags to the
      proxy-ND entry for the IPv6->MAC entry and use that information in
      Neighbor Advertisements when replying to a Solicitation for the
      IPv6 address.

   A PE that implements the proxy-ND function SHOULD have an
   administrative option to define the default Flag to be used in case
   no EVPN ND Extended Community is received for a given IPv6->MAC
   entry.


4. 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].



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   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.


5. Security Considerations

   The same security considerations described in [RFC7432] apply to this
   document.

6. IANA Considerations

   This document requests the registration of a new EVPN Extended
   Community sub-type:

   Sub-Type     Name                     Reference

   0x08         ND Extended Community    [this document]


7. References

7.1. Normative References


   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
   "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI
   10.17487/RFC4861, September 2007, <http://www.rfc-
   editor.org/info/rfc4861>.

   [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>.


7.2. Informative References


8. Acknowledgments


Authors' Addresses



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   Jorge Rabadan (Editor)
   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


































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