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 November 18, 2007
Expires: May 2008
Address Resolution for GMPLS controlled PSC Ethernet
Interfaces
draft-ali-arp-over-gmpls-controlled-ethernet-psc-i-05.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.........................5
4. Security Considerations...................................5
5. IANA Considerations.......................................5
6. References................................................6
6.1. Normative References.................................6
6.2. Informative References...............................6
7. Author's Addresses........................................6
8. Intellectual Property Statement...........................7
9. Copyright Statement.......................................7
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, and considered as point-to-point. The TE links can
be numbered or unnumbered. Similarly, data plane address can
be numbered or unnumbered. Furthermore, the LSP end-points may
or may not be in the same subnets.
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
LSP without extra traffic, or when LSP route changes due to
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re-routing (restoration) or re-optimization, etc. could not be
addressed.
This document provides some 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 numbered TE links are used but the LSP end-points are
in different subnets:
In this case disjoint subnets are used with numbered 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 point-to-point logical link with IPV4
addresses in the same subnet.
2. When the Ethernet data link is numbered but the TE links
are Unnumbered and Ingress LSR does not have loopback
address used by Egress LSR in its forwarding database, and
vice versa.
An example of such scenario is the case when optical and
packet TE links are flooded with different IGP instances.
In this case, we are again faced with the same issue of L2
ARP adjacency resolution between Ingress and Egress LSR.
Egress LSR will reject the ARP request for Ingress LSR as
it will not find the unnumbered address (used by Ingress
LSR) in its forwarding database. This issue can also be
resolve by using Ethernet data link address in the ARP
request.
3. Unnumbered for Ethernet data link:
If the Ethernet data link is unnumbered then the ARP
resolution needs to be done using donor interface IP
address such as Loopback address (/32). However, OSPFv2
adjacency is not established between non-network nodes
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(/32) in Ethernet. In this case, the Ethernet data link
established with GMPLS tunnel would require the router to
support OSPFv2/ISIS adjacency in non-network data plane
segment.
4. 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
the same IP address and same MAC address (this is to address
ARP Latency issue mentioned-above). In the case of unnumbered
interface in Ethernet data link associate with GMPLS tunnel,
ARP resolution SHOULD use donor interface such as Loopback
interface (/32) and OSPFv2 SHOULD establish adjacency in the
non-network IP segment.
4. Security Considerations
This document does not introduce new security issues.
5. IANA Considerations
This document does not require any IANA consideration.
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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
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
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8. Intellectual Property Statement
The IETF takes no position regarding the validity or scope
of any Intellectual Property Rights or other rights that might
be claimed to pertain to the implementation or use of the
technology described in this document or the extent to which
any license under such rights might or might not be available;
nor does it represent that it has made any independent effort
to identify any such rights. Information on the procedures
with respect to rights in RFC documents can be found in BCP 78
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users of this specification can be obtained from the IETF on-
line IPR repository at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its
attention any copyrights, patents or patent applications, or
other proprietary rights that may cover technology that may be
required to implement this standard. Please address the
information to the IETF at ietf-ipr@ietf.org.
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.
This document and the information contained herein are
provided on an "AS IS" basis and THE CONTRIBUTOR, THE
ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY),
THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE
USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR
ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.
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