Internet N. Shen
Internet-Draft E. Chen
Expires: May 2007 Cisco Systems
November 2006
ICMP Extensions for Routing Instances
draft-shen-icmp-routing-inst-00.txt
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Copyright (C) The Internet Society (2006).
Abstract
This document specifies the extensions to ICMP that allows
routing instance information to be included inside the ICMP
packet. These extensions can be used to facilitate the
troubleshooting network problems within a routing domain or
across multiple routing domains.
1. Conventions Used In This Document
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 [10].
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2. Introduction
Internet Control Message Protocol (ICMP) [1] has been widely
used for troubleshooting purposes. This document utilizes the
ICMP multi-part message extension [2] to define a number of
important routing instance objects in ICMP messages.
When using traceroute diagnostic tool through multiple routing
domains, it is useful to have ICMP Time exceeded messages to
include the AS number [3] the router or virtual router
belongs to.
Within the same routing domain, if a network operates with multiple
topologies for IGP [4, 5], it is crucial in network troubleshooting
to know the multi-topology identifier the traceroute packet of
inbound interface is associated with. This information can be
included in the ICMP messages.
With the traditional Interior Gateway Protocol (IGP) diagnostics,
it is useful for the ICMP Time exceeded messages to report
OSPF area [6] the router belongs to or to report the IS-IS [7]
level the router or link belong to when the IGP being IS-IS.
The OSPF area and IS-IS level can also belong to a specific
routing instance the inbound interface is associated with for
the traceroute packets.
A router may support VRRP [9] over a LAN interface and it is
informative to know if the interface has redundancy protection and
it's configured virtual router identifier (VRID).
3. ICMP Multiple-part Message Extension
This document uses the ICMP extension [2]. The ICMP message
MUST include the IP header and leading payload octets of the
original datagram. An ICMP Extension Structure Header MUST
follow the octets from the original datagram and come before
any ICMP Extension Objects.
4. Routing Objects for ICMP
This section defines a number of ICMP routing instance objects that
can be optionally appended to the ICMP Time Exceeded and Destination
Unreachable messages.
4.1 Autonomous System Number Object
The router MAY include the AS number [3] when sending out the
ICMP messages.
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Class-Num = 5
C-type = 1
Length = 8
Object payload:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: AS Number Object
4.2 Multi-Topology ID Object
The router MAY include the MT ID [4, 5] when sending out the
ICMP messages.
Class-Num = 5
C-type = 2
Length = 8
Object payload:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | MT ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: MT ID Object
The MT ID is a 12 bit number for IS-IS MT, and it is a 7 bit number
for OSPF.
4.3 OSPF Area ID Object
The router MAY include the Area ID for OSPF [6] when sending
out the ICMP messages.
Class-Num = 5
C-type = 3
Length = 8
Object payload:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: OSPF Area ID Object
4.4. IS-IS Level Object
The router MAY include the IS-IS level [7] when sending out the
ICMP messages.
Class-Num = 5
C-type = 4
Length = 8
Object payload:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance ID | Reserved | Level |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: IS-IS Level Object
The Instance ID is a 16 bit number [11], default value is zero.
The Level is a 8 bit number, currently defined as following:
1 - IS-IS level-1
2 - IS-IS level-2
3 - IS-IS level-1-2
4.5 IGRP and EIGRP AS ID Object
The router MAY include the IGRP AS ID or EIGRP AS Number when sending
out the ICMP messages.
Class-Num = 5
C-type = 5
Length = 8
Object payload:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IGRP or EIGRP AS ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: IGRP or EIGRP AS ID Object
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The IGRP/EIGRP AS ID is a 32 bit number.
4.6 Virtual Router Identifier Object
The router MAY include the virtual router identifier of VRRP [9]
when sending out the ICMP messages.
Class-Num = 5
C-type = 6
Length = 8
Object payload:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | VR ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: VRID Object
Virtual Router ID is an 8 bit number.
5. Security Considerations
These ICMP extensions can provide operators with additional routing
information during network troubleshooting. It may be desirable to
provide this information only to network operators. This may be
desirable in particular for the IGP routing related objects. The
implementation should allow the configuration of the policy control
over the operation of these objects. For example, an access list
can be attached to check the IP destination of the ICMP packets
with this extension belong to internal network management subnet.
6. IANA Considerations
IANA should should reserve from the ICMP Extension Object registry:
5 for the routing instance objects. IANA should also reserve
from the objects c-types as described in section 4 of this
document.
7. Acknowledgement
TBA.
8. References
8.1. Normative References
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[1] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, September 1981.
[2] Bonica, R., "Modifying ICMP to Support Multi-part Messages",
draft-bonica-internet-icmp-12 (work in progress), October 2006.
[3] Y. Rekhter., "A Border Gateway Protocol 4 (BGP-4)",
RFC 4271, January 2006.
[4] Przygienda, T., "M-ISIS: Multi Topology (MT) Routing in IS-IS",
draft-ietf-isis-wg-multi-topology-11 (work in progress),
April 2006.
[5] Psenak, P., "Multi-Topology (MT) Routing in OSPF",
draft-ietf-ospf-mt-06 (work in progress), February 2006.
[6] Moy, J., "OSPF Version 2", RFC 2328, April 1998.
[7] ISO, "Intermediate system to Intermediate system routing
information exchange protocol for use in conjunction with the
Protocol for providing the Connectionless-mode Network Service
(ISO 8473)," ISO/IEC 10589:1992.
[8] Vohra, Q., "BGP Support for Four-octet AS Number Space",
draft-ietf-idr-as4bytes-12 (work in progress),
May 2006.
[9] Hinden, R., "Virtual Router Redundancy Protocol (VRRP)"
RFC 2338, April 2004.
[10] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[11] Previdi, S., "IS-IS Multi-instance Multi-topology",
draft-previdi-isis-mi-mt-01.txt (work in progress), June 2006.
Author's Addresses
Naiming Shen
Cisco Systems
225 West Tasman Drive
San Jose, CA 95134
USA
Email: naiming@cisco.com
Enke Chen
Cisco Systems
170 West Tasman Drive
San Jose, CA 95134
USA
Email: enkechen@cisco.com
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