Network Working Group S. Gulrajani
Internet-Draft S. Venaas
Intended status: Standards Track cisco Systems
Expires: August 19, 2011 February 15, 2011
An Interface ID Hello Option for PIM
draft-gulrajani-pim-hello-intid-00.txt
Abstract
This document defines a new PIM Hello option to advertise an
interface id that can be used by PIM protocols to uniquely identify
an interface of a neighboring router.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 3
2. Interface Identifier Option . . . . . . . . . . . . . . . . . 4
2.1. Local Interface Identifier . . . . . . . . . . . . . . . . 4
2.2. Router Identifier . . . . . . . . . . . . . . . . . . . . 4
3. Message Format . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . . 10
7.2. Informative References . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
This document defines a new option for use in PIM Hello messages
[RFC4601] to carry an Interface Identifier. A router generates
identifiers for each of its PIM enabled interfaces so that each
interface has a different identifier. The identifiers can optionally
be generated so that they are unique within, e.g., an administrative
domain.
An example where this Interface Identifier can be used is with PIM
PORT [I-D.ietf-pim-port], where a single Transport connection is used
between two routers that have multiple interfaces connecting them.
If these interfaces have unnumbered or IPv6 Link local addresses, the
Interface Identifier included in the PORT Join/Prune message will
identify which interface the message is associated with. For PIM
PORT the Router Identifier is not needed, and it can be set to zero.
1.1. Requirements Notation
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 [RFC2119].
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2. Interface Identifier Option
The Interface Identifier option is used to identify which interface
of a neighboring router a PIM Hello [RFC4601] is sent on. This
allows PIM protocols to refer to, or identify, a particular interface
on a neighboring router.
The Interface Identifier option need only be included in PIM Hello
messages if the router supports protocols that require it. An
implementation MAY choose to always include it. How exactly the
Interface Identifier is used, and the uniqueness requirements, is
left to the specifications of the PIM protocols that make use of it.
It is assumed that different protocols may have different minimum
requirements for stability and uniqueness, but that they have no
maximum requirement. When specified, these protocols should indicate
what their minimum requirements are.
The Interface Identifier consists of 64 bits. The lower 32 bits form
a Local Interface Identifier, and the high 32 bits a Router
Identifier.
2.1. Local Interface Identifier
The 32 bit Local Interface Identifier is selected so that it is
unique among the router's PIM enabled interfaces. That is, there
MUST NOT be two PIM interfaces with the same Local Interface
Identifier. While an interface is up, the Identifier MUST always be
the same once it has been allocated. If an interface goes down and
up, the router SHOULD use the same Identifier. Many systems makes
use of an ifIndex [RFC1213], which can be used as a Local Interface
Identifier.
The Local Interface Identifier MUST be non-zero. The reason for
this, is that some protocols may want to only optionally refer to an
Interface using the Interface Identifier Hello option, and use the
value of 0 to show that it is not referred to. Note that the value
of 0 is not a valid ifIndex as defined in [RFC1213].
2.2. Router Identifier
The 32 bit Router Identifier may be used to uniquely identify the
router. It may be selected to be unique within some administrative
domain, or possibly globally unique. In which scope it needs to be
unique depends on the protocol utilizing it. Routers often have such
an identifier derived from an IPv4 address or manual configuration.
Protocols like BGP [RFC4271] and OSPFv2 [RFC2328] are other protocols
making use of 32 bit identifiers for routers. One may use the same
identifier to construct the Interface Identifier option, provided it
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meets the stability and uniqueness requirements of protocols making
use of this option.
The value 0 has a special meaning for the Router Identifier. It
means that no Router Identifier is used. If a router only supports
protocols that require the Interface Identifier to be unique for one
router (only making use of the Local Interface Identifier), then the
implementation MAY set the Router Identifier to zero.
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3. Message Format
Option Type: Interface Identifier
0 1 2 3
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 = TBD | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Interface Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Allocated Hello Type values can be found in [HELLO-OPT].
Length: In bytes for the value part of the Type/Length/Value
encoding. The Interface Identifier will be 8 bytes long.
Local Interface Identifier: The Local Interface Identifier is a 4
byte identifier that is unique among all PIM enabled interfaces on
a router.
Router Identifier: The Router Identifier is a 4 byte identifier
uniquely identifying the router within some scope. It MAY be 0
when no protocols require a Router Identifier.
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4. Security Considerations
The Interface Identifier is included in PIM Hello Messages. Apart
from the general security considerations for PIM messages, the only
additional concern is what may happen if a spoofed PIM message is
received with the wrong Interface Identifier. That is, if a Hello is
sent with a spoofed source address so that it appears to come from a
known neighbor, and the Interface Identifier is different from what
that neighbor is sending. Also, including this identifier in a
spoofed message when the real neighbor is not sending it, or omitting
it when the real neighbor is sending it. The effects of such attacks
depend on how this Interface Identifier is used by other protocols.
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5. IANA Considerations
IANA is requested to assign a PIM Hello Option value for the
Interface Identifier option defined in this document.
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6. Acknowledgments
The authors thank Yiqun Cai and Heidi Ou for providing valuable
feedback.
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7. References
7.1. Normative References
[I-D.ietf-pim-port]
Farinacci, D., Wijnands, I., Venaas, S., and M. Napierala,
"A Reliable Transport Mechanism for PIM",
draft-ietf-pim-port-04 (work in progress), October 2010.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
7.2. Informative References
[HELLO-OPT]
IANA, "PIM Hello Options", PIM-HELLO-OPTIONS per
RFC4601 http://www.iana.org/assignments/pim-hello-options,
March 2007.
[RFC1213] McCloghrie, K. and M. Rose, "Management Information Base
for Network Management of TCP/IP-based internets:MIB-II",
STD 17, RFC 1213, March 1991.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
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Authors' Addresses
Sameer Gulrajani
cisco Systems
Tasman Drive
San Jose, CA 95134
USA
Email: sameerg@cisco.com
Stig Venaas
cisco Systems
Tasman Drive
San Jose, CA 95134
USA
Email: stig@cisco.com
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