draft-ietf-mpls-icmp-08.txt   rfc4950.txt 
MPLS Working Group R. Bonica Network Working Group R. Bonica
Internet-Draft D. Gan Request for Comments: 4950 Juniper Networks
Intended status: Standards Track Juniper Networks Category: Standards Track D. Gan
Expires: August 4, 2007 D. Tappan D. Tappan
Consultant
C. Pignataro C. Pignataro
Cisco Systems, Inc. Cisco Systems, Inc.
January 31, 2007 August 2007
ICMP Extensions for MultiProtocol Label Switching
draft-ietf-mpls-icmp-08
Status of this Memo
By submitting this Internet-Draft, each author represents that any
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have been or will be disclosed, and any of which he or she becomes
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Internet-Drafts are draft documents valid for a maximum of six months
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The list of Internet-Draft Shadow Directories can be accessed at Status of This Memo
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This Internet-Draft will expire on August 4, 2007. This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
Abstract Abstract
This memo defines an extension object that can be appended to This memo defines an extension object that can be appended to
selected multi-part ICMP messages. This extension permits Label selected multi-part ICMP messages. This extension permits Label
Switching Routers to append MPLS information to ICMP messages, and Switching Routers to append MPLS information to ICMP messages, and
has already been widely deployed. has already been widely deployed.
Table of Contents Table of Contents
1. Conventions Used In This Document . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . . 3
3. Application to TRACEROUTE . . . . . . . . . . . . . . . . . . . 4 3. Application to TRACEROUTE . . . . . . . . . . . . . . . . . . . 3
4. Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. MPLS Label Stack Object . . . . . . . . . . . . . . . . . . . . 5 5. MPLS Label Stack Object . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . . 7 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . . 9
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 [RFC2119].
2. Introduction 1. Introduction
IP routers use the Internet Control Message Protocol, ICMPv4 IP routers use the Internet Control Message Protocol, ICMPv4
[RFC0792] and ICMPv6 [RFC4443], to convey control information to [RFC0792] and ICMPv6 [RFC4443], to convey control information to
source hosts. Network operators use this information to diagnose source hosts. Network operators use this information to diagnose
routing problems. routing problems.
When a router receives an undeliverable IP datagram, it can send an When a router receives an undeliverable IP datagram, it can send an
ICMP message to the host that originated the datagram. The ICMP ICMP message to the host that originated the datagram. The ICMP
message indicates why the datagram could not be delivered. It also message indicates why the datagram could not be delivered. It also
contains the IP header and leading payload octets of the "original contains the IP header and leading payload octets of the "original
datagram" to which the ICMP message is a response. datagram" to which the ICMP message is a response.
MPLS Label Switching Routers (LSR) also use ICMP to convey control MPLS Label Switching Routers (LSR) also use ICMP to convey control
information to source hosts. Section 2.3 of [RFC3032] describes the information to source hosts. Section 2.3 of [RFC3032] describes the
interaction between MPLS and ICMP, and Sections 2.4 and 3 of interaction between MPLS and ICMP, and Sections 2.4 and 3 of
[RFC3032] provide applications of that interaction. [RFC3032] provide applications of that interaction.
When an LSR receives an undeliverable MPLS encapsulated datagram, it When an LSR receives an undeliverable MPLS-encapsulated datagram, it
removes the entire MPLS label stack, exposing the previously removes the entire MPLS label stack, exposing the previously
encapsulated IP datagram. The LSR then submits the IP datagram to an encapsulated IP datagram. The LSR then submits the IP datagram to an
error processing module. Error processing can include ICMP message error processing module. Error processing can include ICMP message
generation. generation.
The ICMP message indicates why the original datagram could not be The ICMP message indicates why the original datagram could not be
delivered. It also contains the IP header and leading octets of the delivered. It also contains the IP header and leading octets of the
original datagram. original datagram.
The ICMP message, however, contains no information regarding the MPLS The ICMP message, however, contains no information regarding the MPLS
skipping to change at page 4, line 5 skipping to change at page 2, line 47
the MPLS label stack. the MPLS label stack.
This memo defines an ICMP extension object that permits an LSR to This memo defines an ICMP extension object that permits an LSR to
append MPLS information to ICMP messages. Selected ICMP messages append MPLS information to ICMP messages. Selected ICMP messages
SHOULD include the MPLS label stack, as it arrived at the router that SHOULD include the MPLS label stack, as it arrived at the router that
is sending the ICMP message. The ICMP message MUST also include the is sending the ICMP message. The ICMP message MUST also include the
IP header and leading payload octets of the original datagram. IP header and leading payload octets of the original datagram.
The ICMP extensions defined in this document must be preceded by an The ICMP extensions defined in this document must be preceded by an
ICMP Extension Structure Header and an ICMP Object Header. Both are ICMP Extension Structure Header and an ICMP Object Header. Both are
defined in [I-D.bonica-internet-icmp]. defined in [RFC4884].
The ICMP extension defined in this document is equally applicable to The ICMP extension defined in this document is equally applicable to
ICMPv4 [RFC0792] and ICMPv6 [RFC4443]. Throughout this document, ICMPv4 [RFC0792] and ICMPv6 [RFC4443]. Throughout this document,
unless otherwise specified, the acronym ICMP refers to multi-part unless otherwise specified, the acronym ICMP refers to multi-part
ICMP messages, encompassing both ICMPv4 and ICMPv6. ICMP messages, encompassing both ICMPv4 and ICMPv6.
2. 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 [RFC2119].
3. Application to TRACEROUTE 3. Application to TRACEROUTE
The ICMP extension defined in this memo supports enhancements to The ICMP extension defined in this memo supports enhancements to
TRACEROUTE. Enhanced TRACEROUTE applications, like older TRACEROUTE. Enhanced TRACEROUTE applications, like older
implementations, indicate which nodes the original datagram visited implementations, indicate which nodes the original datagram visited
en route to its destination. They differ from older implementations en route to its destination. They differ from older implementations
in that they also reflect the original datagram's MPLS encapsulation in that they also reflect the original datagram's MPLS encapsulation
status as it arrived at each node. status as it arrived at each node.
Figure 1 contains sample output from an enhanced TRACEROUTE Figure 1 contains sample output from an enhanced TRACEROUTE
implementation. implementation.
> traceroute 192.0.2.1 > traceroute 192.0.2.1
traceroute to 192.0.2.1 (192.0.2.1), 30 hops max, 40 byte packets traceroute to 192.0.2.1 (192.0.2.1), 30 hops max, 40 byte packets
1 192.0.2.13 (192.0.2.13) 0.661 ms 0.618 ms 0.579 ms 1 192.0.2.13 (192.0.2.13) 0.661 ms 0.618 ms 0.579 ms
2 192.0.2.9 (192.0.2.9) 0.861 ms 0.718 ms 0.679 ms 2 192.0.2.9 (192.0.2.9) 0.861 ms 0.718 ms 0.679 ms
MPLS Label=100048 Exp=0 TTL=1 S=1 MPLS Label=100048 Exp=0 TTL=1 S=1
3 192.0.2.5 (192.0.2.5) 0.822 ms 0.731 ms 0.708 ms 3 192.0.2.5 (192.0.2.5) 0.822 ms 0.731 ms 0.708 ms
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4 192.0.2.1 (192.0.2.1) 0.961 ms 8.676 ms 0.875 ms 4 192.0.2.1 (192.0.2.1) 0.961 ms 8.676 ms 0.875 ms
Figure 1: Enhanced TRACEROUTE Sample Output Figure 1: Enhanced TRACEROUTE Sample Output
4. Disclaimer 4. Disclaimer
This memo does not define the general relationship between ICMP and This memo does not define the general relationship between ICMP and
MPLS. Section 2.3 of [RFC3032] defines this relationship. MPLS. Section 2.3 of [RFC3032] defines this relationship.
The current memo does not define encapsulation specific TTL The current memo does not define encapsulation-specific TTL (Time to
manipulation procedures. It defers to Section 5.4 of RFC 3034 Live) manipulation procedures. It defers to Section 5.4 of RFC 3034
[RFC3034] and Section 10 of [RFC3035] in this matter. [RFC3034] and Section 10 of [RFC3035] in this matter.
When encapsulation specific TTL manipulation procedures defeat the When encapsulation-specific TTL manipulation procedures defeat the
basic TRACEROUTE mechanism, they will also defeat enhanced TRACEROUTE basic TRACEROUTE mechanism, they will also defeat enhanced TRACEROUTE
implementations. implementations.
5. MPLS Label Stack Object 5. MPLS Label Stack Object
The MPLS Label Stack Object can be appended to the ICMP Time Exceeded The MPLS Label Stack Object can be appended to the ICMP Time Exceeded
and Destination Unreachable messages. A single instance of the MPLS and Destination Unreachable messages. A single instance of the MPLS
Label Stack Object represents the entire MPLS label stack, formatted Label Stack Object represents the entire MPLS label stack, formatted
exactly as it was when it arrived at the LSR that sends the ICMP exactly as it was when it arrived at the LSR that sends the ICMP
message. message.
Figure 2 depicts the MPLS Label Stack Object. It must be preceded by Figure 2 depicts the MPLS Label Stack Object. It must be preceded by
an ICMP Extension Structure Header and an ICMP Object Header. Both an ICMP Extension Structure Header and an ICMP Object Header. Both
are defined in [I-D.bonica-internet-icmp]. are defined in [RFC4884].
In the object payload, octets 0-3 depict the first member of the MPLS In the object payload, octets 0-3 depict the first member of the MPLS
label stack. Each remaining member of the MPLS label stack is label stack. Each remaining member of the MPLS label stack is
represented by another 4 octets that share the same format. represented by another 4 octets that share the same format.
Class-Num = 1, MPLS Label Stack Class Class-Num = 1, MPLS Label Stack Class
C-Type = 1, Incoming MPLS Label Stack C-Type = 1, Incoming MPLS Label Stack
Length = 4 + 4 * (number of MPLS LSEs) Length = 4 + 4 * (number of MPLS LSEs)
0 1 2 3 0 1 2 3
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| | | |
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
Figure 2: MPLS Label Stack Object Figure 2: MPLS Label Stack Object
Label: 20 bits Label: 20 bits
Exp: Experimental Use, 3 bits Exp: Experimental Use, 3 bits
S: Bottom of Stack, 1 bit S: Bottom of Stack, 1 bit
TTL: Time to Live, 8 bits TTL: Time to Live, 8 bits
6. Security Considerations 6. Security Considerations
This memo does not specify the conditions that trigger the generation This memo does not specify the conditions that trigger the generation
of ICMP Messages for Labeled IP Packets. It does not define the of ICMP Messages for Labeled IP Packets. It does not define the
interaction between MPLS and ICMP. However, this document defines an interaction between MPLS and ICMP. However, this document defines an
extension that allows an MPLS router to append MPLS information to extension that allows an MPLS router to append MPLS information to
multi-part ICMP messages, and therefore can provide the user of the multi-part ICMP messages, and therefore can provide the user of the
traceroute application with additional information. Consequently, a TRACEROUTE application with additional information. Consequently, a
network operator may wish to provide this information selectively network operator may wish to provide this information selectively
based on some policy; for example, only include the MPLS extensions based on some policy; for example, only include the MPLS extensions
in ICMP messages destined to addresses within the network management in ICMP messages destined to addresses within the network management
blocks with administrative control over the router. An blocks with administrative control over the router. An
implementation could determine whether to include the MPLS Label implementation could determine whether to include the MPLS Label
Stack extensions based upon the destination address of the ICMP Stack extensions based upon the destination address of the ICMP
message, or based on a global configuration option in the router. message, or based on a global configuration option in the router.
Alternatively, an implementation may determine whether to include Alternatively, an implementation may determine whether to include
these MPLS extensions when TTL expires based on the number of label these MPLS extensions when TTL expires based on the number of label
stack entries (depth of the label stack) of the incoming packet. stack entries (depth of the label stack) of the incoming packet.
Finally, an operator can make use of the TTL treatment on MPLS Pipe Finally, an operator can make use of the TTL treatment on MPLS Pipe
Model LSPs defined in [RFC3443] for a TTL-transparent mode of Model LSPs defined in [RFC3443] for a TTL-transparent mode of
operation, that would prevent ICMP Time Exceeded altogether when operation that would prevent ICMP Time Exceeded altogether when
tunneled over the MPLS LSP. tunneled over the MPLS LSP.
7. IANA Considerations 7. IANA Considerations
IANA is requested to assign the following object Class-num in the IANA has assigned the following object Class-num in the ICMP
ICMP Extension Object registry: Extension Object registry:
Class-Num Description Class-Num Description
1 MPLS Label Stack Class 1 MPLS Label Stack Class
IANA is also requested to establish a registry for the corresponding IANA has established a registry for the corresponding class sub-type
class sub-type (C-Type) space, as follows: (C-Type) space, as follows:
MPLS Label Stack Class Sub-types: MPLS Label Stack Class Sub-types:
C-Type Description C-Type Description
0 Reserved
1 Incoming MPLS Label Stack 1 Incoming MPLS Label Stack
0x02-0xF6 Available for assignment
0xF7-0xFF Reserved for private use 0xF7-0xFF Reserved for private use
C-Type values are assignable on a first-come-first-serve (FCFS) basis C-Type values are assignable on a first-come-first-serve (FCFS) basis
[RFC2434]. [RFC2434].
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.bonica-internet-icmp]
Bonica, R., "Extended ICMP to Support Multi-part
Messages", draft-bonica-internet-icmp-16 (work in
progress), January 2007.
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, September 1981. RFC 792, September 1981.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434, IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998. October 1998.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001. Encoding", RFC 3032, January 2001.
[RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control
Message Protocol (ICMPv6) for the Internet Protocol Message Protocol (ICMPv6) for the Internet Protocol
Version 6 (IPv6) Specification", RFC 4443, March 2006. Version 6 (IPv6) Specification", RFC 4443, March 2006.
[RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro,
"Extended ICMP to Support Multi-Part Messages", RFC 4884,
April 2007.
8.2. Informative References 8.2. Informative References
[RFC3034] Conta, A., Doolan, P., and A. Malis, "Use of Label [RFC3034] Conta, A., Doolan, P., and A. Malis, "Use of Label
Switching on Frame Relay Networks Specification", Switching on Frame Relay Networks Specification",
RFC 3034, January 2001. RFC 3034, January 2001.
[RFC3035] Davie, B., Lawrence, J., McCloghrie, K., Rosen, E., [RFC3035] Davie, B., Lawrence, J., McCloghrie, K., Rosen, E.,
Swallow, G., Rekhter, Y., and P. Doolan, "MPLS using LDP Swallow, G., Rekhter, Y., and P. Doolan, "MPLS using LDP
and ATM VC Switching", RFC 3035, January 2001. and ATM VC Switching", RFC 3035, January 2001.
skipping to change at page 8, line 13 skipping to change at page 7, line 13
RFC 3443, January 2003. RFC 3443, January 2003.
Authors' Addresses Authors' Addresses
Ronald P. Bonica Ronald P. Bonica
Juniper Networks Juniper Networks
2251 Corporate Park Drive 2251 Corporate Park Drive
Herndon, VA 20171 Herndon, VA 20171
US US
Email: rbonica@juniper.net EMail: rbonica@juniper.net
Der-Hwa Gan Der-Hwa Gan
Juniper Networks Consultant
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: dhg@juniper.net EMail: derhwagan@yahoo.com
Daniel C. Tappan Daniel C. Tappan
Cisco Systems, Inc. Consultant
250 Apollo Drive
Chelmsford, MA 01824
US
Email: dan.tappan@gmail.com EMail: Dan.Tappan@gmail.com
Carlos Pignataro Carlos Pignataro
Cisco Systems, Inc. Cisco Systems, Inc.
7025 Kit Creek Road 7025 Kit Creek Road
Research Triangle Park, N.C. 27709 Research Triangle Park, NC 27709
US US
Email: cpignata@cisco.com EMail: cpignata@cisco.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
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such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at
ietf-ipr@ietf.org. ietf-ipr@ietf.org.
Acknowledgment Acknowledgement
Funding for the RFC Editor function is provided by the IETF Funding for the RFC Editor function is currently provided by the
Administrative Support Activity (IASA). Internet Society.
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