CCAMP Working Group Zafar Ali
Hassan Sheikh
Internet Draft Cisco Systems, Inc.
Tomohiro Otani
KDDI R&D Laboratories, Inc.
Intended status: BCP March 5, 2007
Expires: September 2007
Address Resolution for GMPLS controlled PSC Ethernet Interfaces
draft-ali-arp-over-gmpls-controlled-ethernet-psc-i-03.txt
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Copyright Notice
Copyright (C) The IETF Trust (2007).
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Abstract
This document outlines some interoperability issues observed with
the use of ARP over GMPLS controlled Ethernet router-to-router
(PSC) interfaces transiting from a non-Ethernet core, e.g., FSC
or LSC GMPLS core. The document also recommends some procedures
to address these issues. The aim of this document is to
facilitate and ensure better interworking of GMPLS-capable Label
Switching Routers (LSRs), based on experience gained in
interoperability testing.
Conventions used in this document
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively.
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.
Table of Contents
1. Introduction...............................................2
2. Address to use for ARP Resolution..........................4
3. Security Considerations....................................4
4. IANA Considerations........................................4
5. References.................................................5
5.1. Normative References..................................5
5.2. Informative References................................5
Author's Addresses............................................5
Intellectual Property Statement...............................5
Disclaimer of Validity........................................6
1. Introduction
This draft addresses the scenario where edge routers are
connected via a non-Ethernet switch capable GMPLS core, e.g., FSC
or LSC core [RFC3471], [RFC3473]. Furthermore, the interfaces
between the router and the optical device (OXC) are Ethernet, and
considered as point-to-point.
When an LSP Path is established between the Ingress Router to
Egress Router, Ethernet interface at the two routers comes up.
However, before this LSP (or interface) can forward any IP
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traffic, MAC address of the remote router needs to be resolved.
The remote MAC address learning is the same procedure used in ARP
resolution to be able to map and ip address to a MAC address on
an Ethernet segment.
End-point MAC address needs to be re-learned once the ARP cache
entries time-out, or every time the path taken by the GMPLS LSP
changes (e.g., due to re-routing or re-optimization). This
introduces latency that is at least equal to the round trip
delay. Such latency adds to the traffic switchover delay and
consequently traffic loss for 1:1 protected LSP without extra
traffic, or when LSP route changes due to re-routing
(restoration) or re-optimization, etc.
Interoperability issues in learning end-point MAC address using
ARP are also found among vendors at various Interoperability
events/ testing efforts. This is because different vendors use
different IP address for ARP resolution. Some LSR vendor uses the
address of the TE link at the end-point, while others adapt to
use tunnel interface address for ARP resolution. When both end-
point TE link address and tunnel interface addresses are
unnumbered, the ARP needs to be performed using loopback
addresses or unique node-ids. Some LSRs do not reply to ARP
request sent to a loopback address unless proxy Arp is used or
unless there is no issues with the L3 reachability of such
loopback address. When tunnel interface is protected, i.e., it
has working and protecting LSP-es, the ARP requested for a given
tunnel IF address should resolve ARP for the physical interfaces
along the path of working and protecting LSP. Issue associated
with ARP latency and traffic loss for 1:1 protected LSP without
extra traffic, or when LSP route changes due to due to re-routing
(restoration) or re-optimization, etc. could not be addressed.
Furthermore tunnel IF address can also be unnumbered.
This document provides some recommendations for the use of the
MAC addresses resolution (ARP resolution) for a GMPLS LSP. The
issue with the use of IP address for ARP can be resolved by
agreeing on use of the IP address used for ARP resolution for
GMPLS tunnels. Instead of using the TE link IP addresses for ARP
resolution, it is recommended that the GMPLS tunnel IP addresses
be used for ARP resolution. This would also address the issue
associated with the use of disjoint subnets used with numbered TE
links between the Ingress LSR and the Optical node, and the
Egress LSR and the optical node. If the GMPLS tunnel is
unnumbered then the ARP resolution can be done using Loopback
addresses associated with the GMPLS tunnel. The use of the GMPLS
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tunnel IP address for ARP resolution can also be extended to the
case where the GMPLS tunnel is providing 1:1 protection i.e. a
working LSP and a protected LSP exists for the GMPLS tunnel. The
protected and the working LSP of the GMPLS tunnel are typically
using different physical interfaces with different MAC address
and TE link addresses. In this case, using the same GMPLS tunnel
IP addresses for resolving ARP for both working and the
protecting links would require the router to associate two
physical interfaces with different MAC addresses with the same
GMPLS tunnel IP address. The use of this implementation along
with the creation of such mapping would also eliminate the
problem of ARP cache timeout on the protecting link; and hence
can address the above-mentioned ARP latency issue related to
protection/ restoration or reoptimization case.
2. Address to use for ARP Resolution
An LSR SHOULD use tunnel interface address for ARP request. An
LSR, based on a local decision, can determine if the Interface is
point-to-point and SHOULD resolve APR using loopback addresses.
Similarly, for point-to-point interfaces, an LSR SHOULD resolve
APR for two or more physical interfaces using the same IP address
(this is to address ARP Latency issue mentioned-above).
In the case of protected tunnels, the ARP cache SHOULD NOT
timeout the ARP entry on both the working and the protecting
LSPs. To meet this requirement, an LSR MAY resolve the ARP at the
GMPLS tunnel setup time and MAY use an infinite ARP timeout (this
is to make sure that ARP entire will not timeout as long as the
GMPLS tunnel is UP). Alternatively, an LSR MAY implement a
periodic ARP refresh scheme for the GMPLS tunnel to keep the ARP
cache refreshed for both the working and the protected LSP.
3. Security Considerations
This document does not introduce new security issues.
4. IANA Considerations
This document does not require any IANA consideration.
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5. References
5.1. Normative References
5.2. Informative References
[RFC3471] Generalized Multi-Protocol Label Switching (GMPLS)
Signaling Functional Description, RFC 3471, L. Berger, et al,
January 2003.
[RFC3473] "Generalized Multi-Protocol Label Switching (GMPLS)
Signaling Resource ReserVation Protocol-Traffic Engineering
(RSVP-TE) Extensions", RFC 3473, L. Berger, et al, January
2003.
Author's Addresses
Zafar Ali
Cisco Systems Inc.
2000 Innovation Dr.,
Kanata, Ontario, K2K 3E8
Canada.
Phone: (613) 889-6158
Email: zali@cisco.com
Hassan Sheikh
C Cisco Systems Inc.
2000 Innovation Dr.,
Kanata, Ontario, K2K 3E8
Canada.
Phone: (613) 254-3356
Email: hassans@cisco.com
Tomohiro Otani
KDDI R&D Laboratories, Inc.
2-1-15 Ohara Fujimino-shi
Saitama, 356-8502. Japan
Phone: +81-49-278-7357
Email: otani@kddilabs.jp
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This document is subject to the rights, licenses and restrictions
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