draft-ietf-bess-evpn-na-flags-02.txt   draft-ietf-bess-evpn-na-flags-03.txt 
BESS Workgroup J. Rabadan, Ed. BESS Workgroup J. Rabadan, Ed.
Internet Draft S. Sathappan Internet Draft S. Sathappan
K. Nagaraj K. Nagaraj
Intended status: Standards Track Nokia Intended status: Standards Track Nokia
Expires: April 22, 2019 October 19, 2018 W. Lin
Juniper
Propagation of IPv6 Neighbor Advertisement Flags in EVPN Expires: October 27, 2019 April 25, 2019
draft-ietf-bess-evpn-na-flags-02
Propagation of ARP/ND Flags in EVPN
draft-ietf-bess-evpn-na-flags-03
Abstract Abstract
The MAC/IP Advertisement route specified in [RFC7432] can optionally An EVPN MAC/IP Advertisement route can optionally carry an IPv4 or
carry IPv4 and IPv6 addresses associated with a MAC address. Remote IPv6 addresses associated with a MAC address. Remote PEs can use this
PEs can use this information to reply locally (act as proxy) to IPv4 information to reply locally (act as proxy) to IPv4 ARP requests and
ARP requests and IPv6 Neighbor Solicitation messages and IPv6 Neighbor Solicitation messages and reduce/suppress the flooding
reduce/suppress the flooding produced by the Address Resolution produced by the Address Resolution procedure. The information
procedure. However, if the Neighbor information is learnt via EVPN, conveyed in the MAC/IP route may not be enough for the remote PE to
the PE would not know if a particular IPv6->MAC pair belongs to a reply to local ARP or ND requests. For example, if a PE learns an
host, a router or a host with an anycast address as this information IPv6->MAC ND entry via EVPN, the PE would not know if that particular
is not carried in the MAC/IP route advertisements. This document IPv6->MAC pair belongs to a host, a router or a host with an anycast
proposes an OPTIONAL advertisement of the Flags defined in [RFC4861] address, as this information is not carried in the MAC/IP route
along with the EVPN MAC/IP Advertisement routes, so that an EVPN PE advertisements. Similarly, other information relevant to the IP->MAC
implementing a proxy-ND function can reply to Neighbor Solicitations ARP/ND entries may be needed. This document proposes an OPTIONAL
with the correct Flag information in Neighbor Advertisements. extended community that is advertised along with an EVPN MAC/IP
Advertisement route and carries information relevant to the ARP/ND
resolution, so that an EVPN PE implementing a proxy-ARP/ND function
can reply to ARP Requests or Neighbor Solicitations with the correct
information.
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. The EVPN Neighbor Discovery (ND) Extended Community . . . . . . 3 1.1 Terminology and Conventions . . . . . . . . . . . . . . . . 3
3. Use of the EVPN ND Extended Community . . . . . . . . . . . . . 4 2. The EVPN ARP/ND Extended Community . . . . . . . . . . . . . . 4
4. Conventions used in this document . . . . . . . . . . . . . . . 4 3. Use of the EVPN ARP/ND Extended Community . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References . . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . . 5 6.2. Informative References . . . . . . . . . . . . . . . . . . 7
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
The MAC/IP Advertisement route specified in [RFC7432] can optionally An EVPN MAC/IP Advertisement route can optionally carry an IPv4 or
carry IPv4 and IPv6 addresses associated with a MAC address. Remote IPv6 addresses associated with a MAC address. Remote PEs can use this
PEs can use this information to reply locally (act as proxy) to IPv4 information to reply locally (act as proxy) to IPv4 ARP requests and
ARP requests and IPv6 Neighbor Solicitation messages and IPv6 Neighbor Solicitation messages and reduce/suppress the flooding
reduce/suppress the flooding produced by the Address Resolution produced by the Address Resolution procedure. The information
procedure. However, if the Neighbor information is learned via EVPN, conveyed in the MAC/IP route may not be enough for the remote PE to
the PE would not know if a particular IPv6->MAC pair belongs to a reply to local ARP or ND requests. For example, if a PE learns an
host or a router as this information is not carried in the MAC/IP IPv6->MAC ND entry via EVPN, the PE would not know if that particular
route advertisements. 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. Similarly, other information relevant to the host
advertised in the MAC/IP Advertisement route may be needed.
This document proposes the OPTIONAL advertisement of the Flags This document proposes an OPTIONAL extended community that is
defined in [RFC4861] along with the EVPN MAC/IP Advertisement routes, advertised along with an EVPN MAC/IP Advertisement route and carries
so that an EVPN PE implementing a proxy-ND function can issue information relevant to the ARP/ND resolution, so that an EVPN PE
Neighbor Advertisement messages conveying the correct Flag implementing a proxy-ARP/ND function can reply to ARP Requests or
information. Neighbor Solicitations with the correct information. In particular,
the Flags defined in [RFC4861] can now be conveyed along with a
MAC/IP Advertisement route, so that an egress EVPN PE can issue
Neighbor Advertisement messages with the correct Flag information.
The Flags are carried in the Neighbor Discovery (ND) EVPN Extended The Flags are carried in the EVPN Address Resolution Protocol (ARP)
Community, as described in the following sections. and Neighbor Discovery (ND) Extended Community, as described in the
following sections.
2. The EVPN Neighbor Discovery (ND) Extended Community 1.1 Terminology and Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
EVPN: Ethernet Virtual Private Networks, as in [RFC7432].
BD: Broadcast Domain, also described in [RFC7432].
IP->MAC: refers to an IP address and MAC address combination that
represents a given host and is added to an Address Resolution
Protocol table or Neighbor Discovery table. This document uses IP-
>MAC generically for IPv4 and IPv6 addresses. When something is
specific to IPv4, the document will use IPv4->MAC and likewise, IPv6-
>MAC will be used when something is specific to IPv6 entries only.
Proxy-ARP/ND: refers to a function on the EVPN PEs by which received
Address Resolution Protocol (ARP) Requests or Neighbor Discovery (ND)
- or Neighbor Solicitation (NS) - messages are replied locally by the
PE, without the need to flood the requests to remote PEs in the BD.
In order to reply to ARP Requests or NS messages, the PE does a
lookup on an ARP/ND table, that is a collection of IP->MAC entries
learned by the PE.
Familiarity with the terminology in [RFC7432] and [RFC4861] is
expected.
2. The EVPN ARP/ND Extended Community
This document defines a new EVPN Extended Community with a Type field 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 value of 0x06 and a Sub-Type 0x08, as allocated by IANA. It MAY be
EVPN MAC/IP Advertisement routes that carry an IPv6 address. advertised along with EVPN MAC/IP Advertisement routes that carry an
IPv4 or 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 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 | | Type=0x06 | Sub-Type= TBD |Flags (1 octet)| Reserved=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved=0 | | Reserved=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following Flags are defined in the third octet of the Extended Flags field:
Community:
R - Router flag. 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| |I| |O|R|
+-+-+-+-+-+-+-+-+
The low-order bit of the third octet is defined as the "Router flag". The following Flags are defined in the Flags field, third octet of
When set, the R-bit indicates that the IPv6->MAC pair advertised the Extended Community:
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.
O - Override flag R - Router Flag (corresponds to Bit 23 of the extended community)
The second bit of the third octet is defined as the "Override flag". Bit 7 of the Flags octet is defined as the "Router flag". When set,
An egress PE will normally advertise IPv6->MAC pairs with the O-bit the R-bit indicates that the IPv6->MAC pair advertised in the MAC/IP
set, and only when IPv6 "anycast" is enabled in the EVI, the PE will Advertisement route along with the extended community belongs to a
send an IPv6->MAC pair with the O-bit = 0. The ingress PE will router. If the R-bit is zero, the IPv6->MAC pair belongs to a "host".
install the proxy-ND entry with the received O-bit and will use this The receiving PE implementing the ND function will use this
information when replying to a Neighbor Solicitation for the IPv6 information in Neighbor Advertisement messages for the associated
address. IPv6 address. This flag is ignored when the extended community is
advertised with a MAC/IP route for an IPv4->MAC pair.
3. Use of the EVPN ND Extended Community O - Override Flag (corresponds to Bit 22 of the extended community)
Bit 6 of the Flags 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 BD, the PE will send an
IPv6->MAC pair with the O-bit = 0. The ingress PE will install the ND
entry with the received O-bit and will use this information when
replying to a Neighbor Solicitation for the IPv6 address. This flag
is ignored when the extended community is advertised with a MAC/IP
route for an IPv4->MAC pair.
An EVPN PE supporting a proxy-ND function and implementing the I - Immutable ARP/ND Binding Flag (corresponds to Bit 20 of the
propagation of the Neighbor Advertisement Flags will follow this extended community)
procedure:
a) Transmission of the EVPN ND Extended Community Bit 4 of the Flags octet is defined as the "Immutable ARP/ND binding
flag". When set, the egress PE indicates that the IP->MAC pair sent
in a MAC/IP route along with the extended community is a configured
ARP/ND entry, and the IP address in the MAC/IP route can only be
bound together with the MAC address specified in the same route.
A PE may learn the IPv6->MAC pair and its associated ND Flags in Bits 0-3 and 5 are not assigned by this document.
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 3. Use of the EVPN ARP/ND Extended Community
In addition to the procedures specified in [RFC7432] a PE An EVPN PE supporting a ND/ARP function and implementing the
receiving a MAC/IP Advertisement route containing an IPv6 address propagation of the ARP/ND Flags will follow this procedure:
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 a) Transmission of the EVPN ARP/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 ARP/ND
Extended Community carrying its associated "R" and "O" Flags.
If an IPv4->MAC or IPv6->MAC pair has been learned in the management
plane (it has been configured) the corresponding MAC/IP Advertisement
route SHOULD be sent along with an ARP/ND extended community with the
flag I set.
This 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 ARP/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 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 a proxy-ND function SHOULD have an
administrative option to define the default Flag to be used in case administrative option to define the default Flag to be used in case
no EVPN ND Extended Community is received for a given IPv6->MAC no EVPN ND Extended Community is received for a given IPv6->MAC
entry. entry. A PE MUST ignore the received R and O Flags for a MAC/IP route
that contains an IPv4 address.
4. Conventions used in this document A PE receiving a MAC/IP Advertisement route containing an IPv4 or
IPv6 address and the I flag set, SHOULD install the IP->MAC entry in
the ARP/ND table as "Immutable binding" entry.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", In a situation where a host (with a IP->MAC configured as Immutable
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and binding) is allowed to move between PEs (that is, the associated MAC
"OPTIONAL" in this document are to be interpreted as described in is non-static), PEs can receive multiple MAC/IP advertisement routes
BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all for the same IP->MAC. In such situations, MAC mobility procedures
capitals, as shown here. dictate the reachability of the MAC. Receiving multiple MAC/IP routes
with I=1 for the same IP but different MAC is considered a
misconfiguration.
5. Security Considerations For example, consider PE1, PE2 and PE3 are attached to the same BD.
PE1 originates a MAC/IP route for IP1->MAC1 with I=1; later on, PE2
also originates a MAC/IP route IP1->MAC1 with a higher sequence
number and I=1. Then all the EVPN PEs attached to the same BD SHOULD
retain their IP1->MAC1 ARP/ND binding but update MAC1's forwarding
destination to PE2. If for some reason, PE3 originates a MAC/IP route
for IP1->MAC2 (even with a higher sequence number), then the EVPN PEs
in the BD SHOULD NOT update their IP1->MAC1 ARP/ND bindings, since
IP1 is bound to MAC1 (MAC2 SHOULD still be programmed in the layer-2
BDs). This is considered a misconfiguration in PE3.
A PE originating a MAC/IP route for IP1->MAC1 with I=1 may also
originate the route with the Static bit set (in the MAC Mobility
extended community). In such a case, the IP1->MAC1 binding is not
only immutable but it cannot move as well.
The flags SHOULD be ignored if they are advertised along with a
MAC/IP Advertisement route that does not contain an IP address.
4. Security Considerations
The same security considerations described in [RFC7432] apply to this The same security considerations described in [RFC7432] apply to this
document. document.
6. IANA Considerations 5. IANA Considerations
This document requests the registration of a new EVPN Extended This document requests the registration of a new EVPN Extended
Community sub-type: Community sub-type:
Sub-Type Name Reference Sub-Type Name Reference
0x08 ND Extended Community [this document] 0x08 ARP/ND Extended Community [this document]
7. References This document also requests the creation of a registry called "ARP/ND
Extended Community Flags octet" where the following allocations are
made:
7.1. Normative References Flag position Name Reference
0-3 Unassigned
4 Immutable ARP/ND Binding Flag (I) [this document]
5 Unassigned
6 Override Flag (O) [this document]
7 Router Flag (R) [this document]
6. References
6.1. Normative References
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI
10.17487/RFC4861, September 2007, <https://www.rfc- 10.17487/RFC4861, September 2007, <https://www.rfc-
editor.org/info/rfc4861>. editor.org/info/rfc4861>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet
VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015,
<https://www.rfc-editor.org/info/rfc7432>. <https://www.rfc-editor.org/info/rfc7432>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March
1997, <https://www.rfc-editor.org/info/rfc2119>. 1997, <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC2119 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC2119
Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017,
<https://www.rfc-editor.org/info/rfc8174>. <https://www.rfc-editor.org/info/rfc8174>.
7.2. Informative References 6.2. Informative References
8. Acknowledgments 7. Acknowledgments
Authors' Addresses Authors' Addresses
Jorge Rabadan (Editor) Jorge Rabadan (Editor)
Nokia Nokia
777 E. Middlefield Road 777 E. Middlefield Road
Mountain View, CA 94043 USA Mountain View, CA 94043 USA
Email: jorge.rabadan@nokia.com Email: jorge.rabadan@nokia.com
Senthil Sathappan Senthil Sathappan
Nokia Nokia
701 E. Middlefield Road 701 E. Middlefield Road
Mountain View, CA 94043 USA Mountain View, CA 94043 USA
Email: senthil.sathappan@nokia.com Email: senthil.sathappan@nokia.com
Kiran Nagaraj Kiran Nagaraj
Nokia Nokia
701 E. Middlefield Road 701 E. Middlefield Road
Mountain View, CA 94043 USA Mountain View, CA 94043 USA
Email: kiran.nagaraj@nokia.com Email: kiran.nagaraj@nokia.com
Wen Lin
Juniper Networks
Email: wlin@juniper.net
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