draft-ietf-mpls-icmp-06.txt   draft-ietf-mpls-icmp-07.txt 
MPLS Working Group R. Bonica MPLS Working Group R. Bonica
Internet-Draft D. Gan Internet-Draft D. Gan
Intended status: Informational Juniper Networks Intended status: Standards Track Juniper Networks
Expires: March 30, 2007 D. Tappan Expires: June 15, 2007 D. Tappan
C. Pignataro
Cisco Systems, Inc. Cisco Systems, Inc.
September 26, 2006 December 12, 2006
ICMP Extensions for MultiProtocol Label Switching ICMP Extensions for MultiProtocol Label Switching
draft-ietf-mpls-icmp-06 draft-ietf-mpls-icmp-07
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
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aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on March 30, 2007. This Internet-Draft will expire on June 15, 2007.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
This memo defines an extension to ICMP that permits Label Switching This memo defines an extension object that can be appended to
Routers to append MPLS information to ICMP messages. This extension selected multi-part ICMP messages. This extension permits Label
has already been widely deployed and this memo is introduced to Switching Routers to append MPLS information to ICMP messages, and
describe existing practice. has already been widely deployed.
Table of Contents Table of Contents
1. Conventions Used In This Document . . . . . . . . . . . . . . . 3 1. Conventions Used In This Document . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Architectural Considerations . . . . . . . . . . . . . . . . . 4 3. Application to TRACEROUTE . . . . . . . . . . . . . . . . . . . 4
4. Application to TRACEROUTE . . . . . . . . . . . . . . . . . . . 4 4. Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. MPLS Label Stack Object . . . . . . . . . . . . . . . . . . . . 5
6. MPLS Stack Entry Object . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 8. Normative References . . . . . . . . . . . . . . . . . . . . . 7
9. Normative References . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 8
1. Conventions Used In This Document 1. Conventions Used In This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [1]. document are to be interpreted as described in RFC2119 [RFC2119].
2. Introduction 2. Introduction
IP routers use the Internet Control Message Protocol (ICMP) [2] to IP routers use the Internet Control Message Protocol, ICMPv4
convey control information to source hosts. Network operators use [RFC0792] and ICMPv6 [RFC4443], to convey control information to
this information to diagnose routing problems. source hosts. Network operators use this information to diagnose
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. Sections 2.3 and 2.4 of RFC 3032 [3] information to source hosts. Sections 2.3 and 2.4 of [RFC3032]
describe the interaction between MPLS and ICMP. describe the interaction between MPLS and ICMP.
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
label stack that encapsulated the original datagram when it arrived label stack that encapsulated the original datagram when it arrived
at the LSR. This omission is significant because the LSR would have at the LSR. This omission is significant because the LSR would have
routed the original datagram based upon information contained by the forwarded the original datagram based upon information contained by
MPLS label stack. the MPLS label stack.
This memo defines an extension to ICMP that permits an LSR to append This memo defines an ICMP extension object that permits an LSR to
MPLS label stack information to ICMP messages. ICMP messages append MPLS information to ICMP messages. Selected ICMP messages
regarding MPLS encapsulated datagrams SHOULD include the MPLS label SHOULD include the MPLS label stack, as it arrived at the router that
stack, as it arrived at the router that is sending the ICMP message. is sending the ICMP message. The ICMP message MUST also include the
The ICMP message MUST also include the IP header and leading payload IP header and leading payload octets of the original datagram.
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 [4]. defined in [I-D.bonica-internet-icmp].
The ICMP extensions defined in this document is equally applicable to
the Internet Control Message Protocol version 6 (ICMPv6) [7].
3. Architectural Considerations
Only layer 3 information should be included in ICMP messages. MPLS The ICMP extension defined in this document is equally applicable to
information can be included only in so much as MPLS participates in ICMPv4 [RFC0792] and ICMPv6 [RFC4443]. Throughout this document,
layer 3 routing. Layer 2 information (e.g., ethernet, PPP) should unless otherwise specified, the acronym ICMP refers to multi-part
not be included in ICMP messages. ICMP messages, encompassing both ICMPv4 and ICMPv6.
4. Application to TRACEROUTE 3. Application to TRACEROUTE
ICMP extensions defined in this memo support enhancements to The ICMP extensions defined in this memo support enhancements to
TRACEROUTE. The enhanced TRACEROUTE application, like older TRACEROUTE. Enhanced TRACEROUTE applications, like older
implementations, indicates which nodes the original datagram visited implementations, indicate which nodes the original datagram visited
en route to its destination. It differs from older implementations en route to its destination. They differ from older implementations
in that it also reflects 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
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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
MPLS Label=100016 Exp=0 TTL=1 S=1 MPLS Label=100016 Exp=0 TTL=1 S=1
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
5. 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
manipulation procedures. It defers to Section 5.4 of RFC 3034 [5] manipulation procedures. It defers to Section 5.4 of RFC 3034
and Section 10 of RFC 3035 [6] 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.
6. MPLS Stack Entry Object 5. MPLS Label Stack Object
This section defines an ICMP extention object that can be appended to The MPLS Label Stack Object can be appended to the ICMP Time Exceeded
the ICMP Time Exceeded and Destination Unreachable messages. A and Destination Unreachable messages. A single instance of the MPLS
single instance of the MPLS Entry Object class represents the entire Label Stack Object represents the entire MPLS label stack, formatted
MPLS label stack, formatted exactly as it was when it arrived at the exactly as it was when it arrived at the LSR that sends the ICMP
LSR that sends the ICMP message. message.
Figure 2 depicts the MPLS Stack Entry 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 [4]. are defined in [I-D.bonica-internet-icmp].
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.
MPLS Stack Entry Class = 1, C-Type = 1. MPLS Label Stack Class = 1, C-Type = 1.
0 1 2 3 0 1 2 3
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
| Label |EXP |S| TTL | | Label |EXP |S| TTL |
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
| | | |
| // Remaining MPLS Stack Entries // | | // Remaining MPLS Stack Entries // |
| | | |
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
Figure 2: MPLS Stack Entry 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
7. Security Considerations 6. Security Considerations
This memo presents no security considerations beyond those already This memo does not specify the conditions that trigger the generation
presented by current ICMP applications (e.g., traceroute). of ICMP Messages for Labeled IP Packets. It does not define the
interaction between MPLS and ICMP. However, this document defines an
extension that allows an MPLS router to append MPLS information to
multi-part ICMP messages, and therefore can provide the user of the
traceroute application with additional information. Consequently, a
network operator may wish to provide this information selectively
based on some policy; for example, only include the MPLS extensions
in ICMP messages destined to addresses within the network management
blocks with administrative control over the router. An
implementation could determine whether to include the MPLS Label
Stack extensions based upon the destination address of the ICMP
message, or based on a global configuration option in the router.
Alternativelly, an implementation may determine whether to include
these MPLS extensions when TTL expires based on the number of label
stack entries (depth of the label stack) of the incoming packet.
Finally, an operator can make use of the TTL treatment on MPLS Pipe
Model LSPs defined in [RFC3443] for a TTL-transparent mode of
operation, that would prevent ICMP Time Exceeded altogether when
tunneled over the MPLS LSP.
8. IANA Considerations 7. IANA Considerations
IANA should should reserve an object class and object type for the IANA is requested to assign the following object Class-num in the
MPLS Stack Entry Object from the ICMP Extension Object registry. ICMP Extension Object registry:
9. Normative References Class-Num Description
1 MPLS Label Stack Class
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement IANA is also requested to establish a registry for the corresponding
Levels", BCP 14, RFC 2119, March 1997. class sub-type (C-Type) space, as follows:
[2] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, MPLS Label Stack Class Sub-types:
September 1981.
[3] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., C-Type Description
Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032, 1 Incoming MPLS Label Stack
January 2001. 0xF7-0xFF Reserved for private use
[4] Bonica, R., "Modifying ICMP to Support Multi-part Messages", C-Type values are assignable on a first-come-first-serve (FCFS) basis
draft-bonica-internet-icmp-08 (work in progress), August 2006. [RFC2434].
[5] Conta, A., Doolan, P., and A. Malis, "Use of Label Switching on 8. Normative References
Frame Relay Networks Specification", RFC 3034, January 2001.
[6] Davie, B., Lawrence, J., McCloghrie, K., Rosen, E., Swallow, G., [I-D.bonica-internet-icmp]
Rekhter, Y., and P. Doolan, "MPLS using LDP and ATM VC Bonica, R., "Modifying ICMP to Support Multi-part
Switching", RFC 3035, January 2001. Messages", draft-bonica-internet-icmp-13 (work in
progress), December 2006.
[7] Conta, A., Deering, S., and M. Gupta, "Internet Control Message [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) RFC 792, September 1981.
Specification", RFC 4443, March 2006.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001.
[RFC3034] Conta, A., Doolan, P., and A. Malis, "Use of Label
Switching on Frame Relay Networks Specification",
RFC 3034, January 2001.
[RFC3035] Davie, B., Lawrence, J., McCloghrie, K., Rosen, E.,
Swallow, G., Rekhter, Y., and P. Doolan, "MPLS using LDP
and ATM VC Switching", RFC 3035, January 2001.
[RFC3443] Agarwal, P. and B. Akyol, "Time To Live (TTL) Processing
in Multi-Protocol Label Switching (MPLS) Networks",
RFC 3443, January 2003.
[RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control
Message Protocol (ICMPv6) for the Internet Protocol
Version 6 (IPv6) Specification", RFC 4443, March 2006.
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
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US US
Email: dhg@juniper.net Email: dhg@juniper.net
Daniel C. Tappan Daniel C. Tappan
Cisco Systems, Inc. Cisco Systems, Inc.
250 Apollo Drive 250 Apollo Drive
Chelmsford, MA 01824 Chelmsford, MA 01824
US US
Email: tappan@cisco.com Email: dan.tappan@gmail.com
Carlos Pignataro
Cisco Systems, Inc.
7025 Kit Creek Road
Research Triangle Park, N.C. 27709
US
Email: cpignata@cisco.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
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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