CCAMP Working Group Zafar Ali
Hassan Sheikh
Internet Draft Cisco Systems, Inc.
Tomohiro Otani
KDDI R&D Laboratories, Inc.
Hidetsugu Sugiyama
Juniper Networks
Intended status: BCP February 25, 2008
Expires: August 2008
Use of addresses in resolving ARP for GMPLS LSPs
draft-ali-arp-over-gmpls-controlled-ethernet-psc-i-06.txt
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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 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 [RFC2119].
Table of Contents
1. Terminology...............................................2
2. Introduction..............................................3
3. Address to use for ARP Resolution.........................4
4. Security Considerations...................................5
5. IANA Considerations.......................................5
6. References................................................5
6.1. Normative References.................................5
6.2. Informative References...............................5
7. Author's Addresses........................................5
8. Intellectual Property Statement...........................6
9. Copyright Statement.......................................6
1. Terminology
The control plane address refers to the address assigned to
the TE Links. This address is used to advertise TE link in the
TE topology.
The data plane address refers to the address assigned to the
Ethernet data link or the address assigned to the GMPLS tunnel
interface. This address is used at PSC (packet switching
capable) layer for forwarding traffic over the GMPLS LSP. The
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terms the data plane address and the GMPLS tunnel address are
used synonymously.
2. 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 This draft addresses the case of TE numbered TE
links. Furthermore, the LSP end-points may or may not be in
the same subnets. The case where data links are unnumbered is
beyond the scope of this document.
When an LSP Path is established between the Ingress and Egress
LSRs, Ethernet interface at the two LSRs comes up. Unlike POS
links where a L2 adjacency resolution is not required, the
Ethernet links require that the ARP be resolved (also known as
Layer 2 MAC address) before any forwarding works on this link.
Specifically, before a GMPLS LSP with Ethernet end-point can
forward any IP 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 an ip
address to a MAC address on an Ethernet Data Link.
End-point MAC address needs to be re-learned once the ARP
cache entries time-out, or every time the Ethernet Data Link
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 in
the Ethernet Data Link 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 control plane address of
the TE link at the end-point, while others adapt to use data
plane address on the Ethernet Data Link for ARP resolution.
When GMPLS tunnel is protected, i.e., it has working and
protecting LSP-es, the ARP requested for a given Ethernet IF
address should resolve ARP for the physical Ethernet
interfaces along the path of working and protecting LSP. Issue
associated with ARP latency and traffic loss for 1:1 protected
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LSP without extra traffic, or when LSP route changes due to
re-routing (restoration) or re-optimization, etc. could not be
addressed.
This document provides recommendations for the use of the MAC
addresses resolution (ARP resolution) for a GMPLS LSP. In the
following, we provide reason behind recommendations provided
in this document.
Consider following scenarios.
1. When the LSP end-points are in different subnets:
In this case disjoint subnets are used with TE links
between the Ingress LSR and the Optical node, and the
Egress LSR and the optical node. In this situation we
really have no way of resolving ARP using the addresses of
the underlying TE link, without using static ARP entries.
The issue is that the subnets are different so the ARP
request received by Egress LSR from Ingress LSR will be
rejected as it is not known to Egress LSR, and vice versa.
This issue can be resolved when the ARP request uses
Ethernet data link address. This is because the Ethernet
data link is a logical link with IPV4 addresses in the
same subnet.
2. GMPLS Protection Case:
The use of the protected Ethernet data link along with
GMPLS LSP for ARP resolution can also extended to the case
where the GMPLS tunnel is provided end-to-end 1:1
protection i.e. a working LSP and a protected LSP of the
GMPLS tunnel are typically using different physical
interfaces (different MAC addresses) with different TE
Link. This issue can be resolved by using the same IP
address and same MAC address for ARP resolution over
working and protecting interfaces. The use of this
implementation along with the creation of such mapping
would also eliminate the problem of ARP cache timeout on
the protected link; and hence can address the above-
mentioned ARP latency issue related to protection case.
3. Address to use for ARP Resolution
An LSR SHOULD use data plane address on Ethernet data link for
ARP request. For protected point-to-point interfaces, an LSR
SHOULD resolve APR for two or more physical interfaces using
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the same IP address and same MAC address (this is to address
ARP Latency issue mentioned-above).
4. Security Considerations
TBA.
5. IANA Considerations
This document does not require any IANA consideration.
6. References
6.1. Normative References
[RFC2119] "Key words for use in RFCs to Indicate Requirement
Levels", S. Bradner, http://tools.ietf.org/html/rfc2119.
6.2. 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.
7. 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
Cisco Systems Inc.
2000 Innovation Dr.,
Kanata, Ontario, K2K 3E8
Canada.
Phone: (613) 254-3356
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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
Hidetsugu Sugiyama
Juniper Networks
Email: hidet@juniper.net
8. Intellectual Property Statement
The IETF takes no position regarding the validity or scope
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The IETF invites any interested party to bring to its
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9. Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and
restrictions contained in BCP 78, and except as set forth
therein, the authors retain all their rights.
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This document and the information contained herein are
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