BESS Workgroup J. Rabadan, Ed.
Internet Draft S. Sathappan
K. Nagaraj
Intended status: Standards Track Alcatel-Lucent
Expires: January 7, 2016 July 6, 2015
Propagation of IPv6 Neighbor Advertisement Flags in EVPN
draft-snr-bess-evpn-na-flags-02
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.
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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
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at any time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on January 7, 2015.
Copyright Notice
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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
0xXX 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)
Alcatel-Lucent
777 E. Middlefield Road
Mountain View, CA 94043 USA
Email: jorge.rabadan@alcatel-lucent.com
Senthil Sathappan
Alcatel-Lucent
701 E. Middlefield Road
Mountain View, CA 94043 USA
Email: senthil.sathappan@alcatel-lucent.com
Kiran Nagaraj
701 E. Middlefield Road
Mountain View, CA 94043 USA
Alcatel-Lucent
Email: kiran.nagaraj@alcatel-lucent.com
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