draft-ietf-mpls-icmp-02.txt   draft-ietf-mpls-icmp-03.txt 
MPLS Working Group R.Bonica MPLS Working Group R.Bonica
Internet Draft MCIWorldCom Internet-Draft D. Gan
Document: draft-ietf-mpls-icmp-02.txt D.Tappan Expires: February 3, 2006 Juniper Networks
Cisco Systems D. Tappan
D.Gan Cisco Systems, Inc.
Juniper Networks August 2, 2005
August 2000
ICMP Extensions for MultiProtocol Label Switching ICMP Extensions for MultiProtocol Label Switching
draft-ietf-mpls-icmp-03
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with By submitting this Internet-Draft, each author represents that any
all provisions of Section 10 of [RFC-2026]. applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
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1. Abstract This Internet-Draft will expire on February 3, 2006.
The current memo proposes extensions to ICMP that permit Label Copyright Notice
Switching Routers to append MPLS information to ICMP messages.
2. Conventions used in this document Copyright (C) The Internet Society (2005).
Abstract
This memo proposes extensions to ICMP that permit Label Switching
Routers to append MPLS information to ICMP messages.
Table of Contents
1. Conventions Used In This Document . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Application to TRACEROUTE . . . . . . . . . . . . . . . . . . 5
4. Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1 Common Header . . . . . . . . . . . . . . . . . . . . . . 8
5.2 Object Header . . . . . . . . . . . . . . . . . . . . . . 8
5.3 MPLS Stack Entry Object Class . . . . . . . . . . . . . . 9
5.4 Extended Payload Object Class . . . . . . . . . . . . . . 10
6. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9. Normative References . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . 15
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 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
this document are to be interpreted as described in [RFC-2119]. document are to be interpreted as described in RFC2119 [1].
3. Introduction 2. Introduction
Routers and destination hosts use the Internet Control Message IP routers use the Internet Control Message Protocol (ICMP) [2] to
Protocol (ICMP) [RFC-792] to convey control information to source convey control information to source hosts. Network operators use
hosts. Network operators use this information to diagnose routing this information to diagnose routing problems.
problems.
Bonica, Tappan, Hwa Draft-Expires February 2001 1
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". datagram".
In this document, the term "original datagram" refers to the In this document, the term "original datagram" refers to the datagram
datagram to which the ICMP message is a response. 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 [ENCODE] information to source hosts. Sections 2.3 and 2.4 of RFC 3032 [3]
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 a encapsulated IP datagram. The LSR then submits the IP datagram to an
network-forwarding module for error processing. Error processing can error processing module. Error processing can include ICMP message
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, includes no information regarding the The ICMP message, however, contains no information regarding the MPLS
MPLS label stack that encapsulated the original datagram when it label stack that encapsulated the original datagram when it arrived
arrived at the LSR. This omission is significant because the LSR at the LSR. This omission is significant because the LSR would have
would have routed the original datagram based upon information routed the original datagram based upon information contained by the
contained by the MPLS label stack. MPLS label stack.
The current memo proposes extensions to ICMP that permit an LSR to This memo proposes extensions to ICMP that permit an LSR to append
append MPLS label stack information to ICMP messages. ICMP messages MPLS label stack information to ICMP messages. ICMP messages
regarding MPLS encapsulated datagrams SHOULD include the MPLS label regarding MPLS encapsulated datagrams SHOULD include the MPLS label
stack, as it arrived at the router that is sending the ICMP message. stack, as it arrived at the router that is sending the ICMP message.
The ICMP message MUST also include the IP header and leading payload The ICMP message MUST also include the IP header and leading payload
octets of the original datagram. octets of the original datagram.
Network operators will use this information to diagnose routing 3. Application to TRACEROUTE
problems.
4. Motivation
ICMP extensions defined in the current memo support enhancements to ICMP extensions defined in this memo support enhancements to
TRACEROUTE. The enhanced TRACEROUTE, like older implementations, TRACEROUTE. The enhanced TRACEROUTE, like older implementations,
indicates which nodes the original datagram visited en route to its indicates which nodes the original datagram visited en route to its
ultimate destination. It differs from older implementations in that destination. It differs from older implementations in that it also
it also indicates the original datagrams MPLS encapsulation status indicates the original datagrams MPLS encapsulation status as it
as it arrived at each node. arrived at each node.
Figure 1 contains sample output from an enhanced TRACEROUTE Figure 1 contains sample output from an enhanced TRACEROUTE
implementation. implementation.
Bonica,Tappan,Gan Draft-Expires February 2001 2 > traceroute 100.100.6.1
>Traceroute 166.45.2.74
traceroute to 166.45.2.74, 30 hops max, 40 byte packets
1 166.45.5.1 1.281 ms 1.103 ms 1.096 ms
2 166.45.4.1 1.281 ms 1.103 ms 1.096 ms mplsLabel1=2001
mplsExpBits1=0
3 166.45.3.1 1.281 ms 1.103 ms 1.096 ms mplsLabel1=2002
mplsExpBits1=0
4 166.45.6.1 1.281 ms 1.103 ms 1.096 ms mplsLabel1=2003
mplsExpBits1=0
5 166.45.2.1 1.281 ms 1.103 ms 1.096 ms
6 166.45.2.74 1.281 ms 1.103 ms 1.096 ms
Figure 1. Enhanced TRACEROUTE sample output traceroute to 100.100.6.1 (100.100.6.1), 30 hops max, 40 byte packets
5. Disclaimer 1 10.1.1.2 (10.1.1.2) 0.661 ms 0.618 ms 0.579 ms
The current memo does not define the general relationship between 2 10.1.12.2 (10.1.12.2) 0.861 ms 0.718 ms 0.679 ms
ICMP and MPLS. Sections 2.3 and 2.4 of [ENCODE] define this
relationship.
Specifically, this document defers to [ENCODE] with respect to the MPLS Label=100048 Exp=0 TTL=1 S=1
3 10.1.24.2 (10.1.24.2) 0.822 ms 0.731 ms 0.708 ms
MPLS Label=100016 Exp=0 TTL=1 S=1
4 10.100.6.1 (10.100.6.1) 0.961 ms 8.676 ms 0.875 ms
Figure 1: Enhanced TRACEROUTE Sample Output
4. Disclaimer
This memo does not define the general relationship between ICMP and
MPLS. Sections 2.3 and 2.4 of RFC3032 define this relationship.
Specifically, this document defers to RFC3032 with respect to the
following issues: following issues:
- conditions upon which an LSR emits ICMP messages - conditions upon which an LSR emits ICMP messages
- handling of ICMP messages bound for hosts that are identified
by private addresses - handling of ICMP messages bound for hosts that are identified by
private addresses
The current memo does not define encapsulation specific TTL The current memo does not define encapsulation specific TTL
manipulation procedures. It defers to Section 10 of [MPLSATM] and manipulation procedures. It defers to Section 5.4 of RFC 3034 [4]
Section 5.4 of [MPLSFRAME] in this matter. and Section 10 of RFC 3035 [5] 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 basic TRACEROUTE mechanism, they will also defeat enhanced TRACEROUTE
TRACEROUTE implementations. implementations.
The current memo does not address extensions to ICMPv6. These should The current memo does not address extensions to ICMPv6. These should
be addressed in a separate draft. be addressed in a separate draft.
6. Formal Syntax 5. Syntax
This section defines a data structure that an LSR can append to This section defines a data structure that an LSR can append to
selected ICMP messages. The data structure contains the MPLS label selected ICMP messages. The data structure contains the MPLS label
stack that encapsulated the original datagram when it arrived at the stack that encapsulated the original datagram when it arrived at the
LSR. LSR.
The data structure defined herein can be appended to the following In theory, the data structure defined herein can be appended to the
ICMP message types: following ICMP message types:
Bonica,Tappan,Gan Draft-Expires February 2001 3 Destination Unreachable
1) Destination Unreachable
2) Time Exceeded Time Exceeded
3) Parameter Problem
4) Source Quench Parameter Problem
5) Redirect
Source Quench
Redirect
However, in practice, it would only be useful when appended to the
Destination Unreachable and Time Exceeded messages.
According to RFC-792, bytes 0 through 19 of any ICMP message contain According to RFC-792, bytes 0 through 19 of any ICMP message contain
a header whose format is analogous to that of the IP datagram. Bytes a header whose format is analogous to that of the IP datagram. Bytes
20 through 23 contain an ICMP message type, code and checksum. Bytes 20 through 23 contain an ICMP message type, code and checksum. Bytes
24 through 27 contain message specific data. 24 through 27 contain message specific data.
Also according to RFC-792, the final field contained by each of the Also according to RFC-792, the final field contained by each of the
ICMP message types listed above begins at byte 28. It reflects the ICMP message types listed above begins at byte 28. It reflects the
IP header and leading 64 bits of the original datagram. [RFC-1812] IP header and leading 64 bits of the original datagram. RFC 1812 [6]
recommends that this final field be extended to include as much of recommends that this final field be extended to include as much of
the original datagram as possible. the original datagram as possible.
When an LSR appends the data structure defined herein to an ICMP When an LSR appends the data structure defined herein to an ICMP
message, the final field of the ICMP message body MUST contain the message, the final field of the ICMP message body MUST contain the
first 128 octets of the original datagram. At least 20 of these 128 first 128 octets of the original datagram. At least 20 of these 128
octets represent the IP header of the original datagram. octets represent the IP header of the original datagram.
If the original datagram was shorter than 128 octets, the final If the original datagram was shorter than 128 octets, the final field
field MUST be padded with 0's. MUST be padded with 0's.
When an LSR appends the data structure defined herein to an ICMP When an LSR appends the data structure defined herein to an ICMP
message, the ICMP "total length" MUST be equal to the data structure message, the ICMP "total length" MUST be adjusted appropriately to
length plus 156. The first octet of the data structure must be include the data structure.
displaced 156 octets from the beginning of the ICMP message.
The data structure defined in this section consists of a common The data structure defined in this section consists of a common
header followed by object instances. Each object instance consists header followed by object instances. Each object instance consists
of an object header plus contents. of an object header plus contents.
Currently, two object classes are defined. One object class contains Currently, two object classes are defined. One object class contains
an entire MPLS label stack, formatted exactly as it was when it an entire MPLS label stack, formatted exactly as it was when it
arrived at the LSR that sends the ICMP message. The other contains arrived at the LSR that sends the ICMP message. The other contains
some portion of the original datagram that could not be included in some portion of the original datagram that could not be included in
the final field of the ICMP message body (i.e., the octet 129 and the final field of the ICMP message body (i.e., the octet 129 and
beyond). beyond).
Both object classes are optional. Both object classes are optional.
In the future, additional object classes may be defined. In the future, additional object classes may be defined.
Bonica,Tappan,Gan Draft-Expires February 2001 4 5.1 Common Header
6.1 Common Header
0 1 2 3 0 1 2 3
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
| Vers | (Reserved) | Checksum | | Vers | (Reserved) | Checksum |
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
Figure 2: Common Header
The fields in the common header are as follows: The fields in the common header are as follows:
Vers: 4 bits Vers: 4 bits
ICMP extension version number. ICMP extension version number. This is version 2.
This is version 2.
Checksum: 16 bits Checksum: 16 bits
The one's complement of the one's complement sum of the data The one's complement of the one's complement sum of the data
structure, with the checksum field replaced by zero for the purpose structure, with the checksum field replaced by zero for the
of computing the checksum. An all-zero value means that no checksum purpose of computing the checksum. An all-zero value means that
was transmitted. no checksum was transmitted.
If the checksum field contains a value other than described above, If the checksum field contains a value other than described above,
the ICMP message does not include the extensions described in this the ICMP message does not include the extensions described in this
memo. This, however, does not imply that the ICMP message is memo. This, however, does not imply that the ICMP message is
malformed. It may be in strict compliance with RFC-1812. malformed. It may be in strict compliance with RFC-1812.
Reserved: Must be set to 0. Reserved: Must be set to 0.
6.2 Object Header 5.2 Object Header
Every object consists of one or more 32-bit words with a one-word Every object consists of one or more 32-bit words with a one-word
header, with the following format: header. The following is the format of the one-word header:
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
| Length | Class-Num | C-Type | | Length | Class-Num | C-Type |
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
| | | |
| // (Object contents) // | | // (Object contents) // |
| | | |
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
Figure 3: Object Header
An object header has the following fields: An object header has the following fields:
Length: 16 bits Length: 16 bits
Length of the object, measured in octets, including the object Length of the object, measured in octets, including the object
header and object contents. header and object contents.
Bonica,Tappan,Gan Draft-Expires February 2001 5
Class-Num: 8 bits Class-Num: 8 bits
Identifies object class. Identifies object class.
C-Type: 8 bits C-Type: 8 bits
Identifies object sub-type. Identifies object sub-type.
6.3 MPLS Stack Entry Object Class 5.3 MPLS Stack Entry Object Class
A single instance of the MPLS Entry Object class represents the A single instance of the MPLS Entry Object class represents the
entire MPLS label stack, formatted exactly as it was when it arrived entire MPLS label stack, formatted exactly as it was when it arrived
at the LSR that sends the ICMP message at the LSR that sends the ICMP message
In the illustration below, octets 0-3 depict the first member of the In the illustration below, octets 0-3 depict the first member of the
MPLS label stack. Each remaining member of the MPLS label stack is MPLS 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.
Syntax follows: Syntax follows:
skipping to change at line 277 skipping to change at page 10, line 14
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 4: MPLS Stack Entry Object Class
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
6.4 Extended Payload Object Class 5.4 Extended Payload Object Class
An instance of the Extended Payload Object class represents some An instance of the Extended Payload Object class represents some
portion of the original datagram that could not be fit in the final portion of the original datagram that could not be fit in the final
field of the ICMP message body (i.e., octets beyond 128). field of the ICMP message body (i.e., octets beyond 128).
Bonica,Tappan,Gan Draft-Expires February 2001 6
Syntax follows: Syntax follows:
MPLS Stack Entry Class = 2, C-Type = 1. MPLS Stack Entry Class = 2, C-Type = 1.
0 1 2 3 0 1 2 3
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
| | | |
| // Additional bytes of original datagram // | | // Additional bytes of original datagram // |
| | | |
+-------------+-------------+-------------+-------------+ +-------------+-------------+-------------+-------------+
7. Backward Compatibility Figure 5: Extended Payload Object Class
ICMP extensions proposed in this document MUST be backward 6. Backward Compatibility
compatible with the syntax described in RFC-792. Extensions proposed
in this memo MUST NOT change or deprecate any field defined in RFC- ICMP extensions proposed in this document MUST be backward compatible
792. with the syntax described in RFC-792. Extensions proposed in this
memo MUST NOT change or deprecate any field defined in RFC-792.
The extensions defined herein are in keeping with the spirit, if not The extensions defined herein are in keeping with the spirit, if not
the letter of RFC-1812. In order to support IP-in-IP tunneling, RFC- the letter of RFC-1812. In order to support IP-in-IP tunneling, RFC-
1812 extends the final field of selected ICMP messages to include a 1812 extends the final field of selected ICMP messages to include a
greater portion of the original datagram. Unfortunately, it extends greater portion of the original datagram. Unfortunately, it extends
this field to a variable length without adding a length attribute. this field to a variable length without adding a length attribute.
This memo binds the length of that final field to an arbitrarily This memo binds the length of that final field to an arbitrarily
large value (128 octets). Fixing the length of that field large value (128 octets). Fixing the length of that field
facilitates extension of the ICMP message. An additional object is facilitates extension of the ICMP message. An additional object is
provided through which octets 129 and beyond can be appended to the provided through which octets 129 and beyond can be appended to the
ICMP message. ICMP message.
As few datagrams contain L3 or L4 header information beyond octet As few datagrams contain L3 or L4 header information beyond octet
128, it is unlikely that the extensions described herein will 128, it is unlikely that the extensions described herein will disable
disable any applications that rely upon RFC-1812 style ICMP any applications that rely upon RFC-1812 style ICMP messages.
messages.
8. Security Considerations 7. Security Considerations
This memo presents no security considerations beyond those already This memo presents no security considerations beyond those already
presented by current ICMP applications (e.g., traceroute). presented by current ICMP applications (e.g., traceroute).
9. References 8. IANA Considerations
[ARCH], Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol IANA should establish a registry of ICMP extention classes and class-
Label Switching Architecture", Internet Draft <draft-ietf-mpls-arch- sub-types.
06.txt>, August, 1999
Bonica,Tappan,Gan Draft-Expires February 2001 7 9. Normative References
[ENCODE], Rosen, E., Rekhter, Y., Tappan, D, Farinacci, D.,
Fedorkow, G., Li, T., Conta, A., "MPLS Stack Encoding", Internet
Draft, <draft-ietf-mpls-label-encapse-07.txt>, September 1999.
[MPLSATM], Davie, B., Lawrence, J., McCloghrie, K., Rekhter, Y., [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Rosen, E., Swallow, G, "MPLS using LDP and ATM VC Switching", Levels", BCP 14, RFC 2119, March 1997.
<draft-ietf- mpls-atm-04.txt>, June 2000.
[MPLSFRAME], Conta, A., Doolan, P., Malis, A., "Use of Label [2] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792,
Switching on Frame Relay Networks", <draft-ietf-mpls-fr-06.txt>, September 1981.
June, 2000.
[RFC-792], Postel, J., "Internet Control Message Protocol", RFC 792, [3] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D.,
ISI, September 1981. Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032,
January 2001.
[RFC-1812], Baker, F., "Requirements for IP Version 4 Routers", RFC [4] Conta, A., Doolan, P., and A. Malis, "Use of Label Switching on
1812, June 1995. Frame Relay Networks Specification", RFC 3034, January 2001.
[RFC-2026], Bradner, S., "Internet Standards Process Revision 3", [5] Davie, B., Lawrence, J., McCloghrie, K., Rosen, E., Swallow, G.,
RFC 2026, Harvard University, October 1996. Rekhter, Y., and P. Doolan, "MPLS using LDP and ATM VC
Switching", RFC 3035, January 2001.
[RFC-2119], Bradner, S,, "Key words for use in RFCs to Indicate [6] Baker, F., "Requirements for IP Version 4 Routers", RFC 1812,
Requirement Levels", RFC 2119, Harvard University, March 1997 June 1995.
10. Acknowledgments Authors' Addresses
Thanks to Yakov Rekhter and Mike Heard for their contributions to Ronald P. Bonica
this memo. Juniper Networks
2251 Corporate Park Drive
Herndon, VA 20171
US
11. Author's Addresses Email: rbonica@juniper.net
Ronald P. Bonica Der-Hwa Gan
MCI WorldCom Juniper Networks
22001 Loudoun County Pkwy 1194 N. Mathilda Ave.
Ashburn, Virginia, 20147 Sunnyvale, CA 94089
Phone: 703 886 1681 US
Email: rbonica@mci.net
Email: dhg@juniper.net
Daniel C. Tappan Daniel C. Tappan
Cisco Systems Cisco Systems, Inc.
250 Apollo Drive 250 Apollo Drive
Chelmsford, Massachusetts, 01824 Chelmsford, MA 01824
US
Email: tappan@cisco.com Email: tappan@cisco.com
Der-Hwa Gan Intellectual Property Statement
Juniper Networks
385 Ravendale Drive
Mountain View, California 94043
Bonica,Tappan,Gan Draft-Expires February 2001 8
Email: dhg@juniper.net
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Bonica,Tappan,Gan Draft-Expires February 2001 10 Disclaimer of Validity
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