wdiff draft-ietf-mpls-icmp-02.txt draft-ietf-mpls-icmp-03.txt

MPLS Working Group R.Bonica
Internet Draft MCIWorldCom
Document: draft-ietf-mpls-icmp-02.txt D.Tappan
Cisco Systems
D.Gan R. Bonica
Internet-Draft D. Gan
Expires: February 3, 2006 Juniper Networks
D. Tappan
Cisco Systems, Inc.
August 2000 2, 2005

ICMP Extensions for MultiProtocol Label Switching
draft-ietf-mpls-icmp-03

Status of this Memo

This document

By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is an Internet-Draft aware
have been or will be disclosed, and is any of which he or she becomes
aware will be disclosed, in full conformance accordance with
all provisions of Section 10 6 of [RFC-2026]. BCP 79.

Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
http://www.ietf.org/ietf/1id-abstracts.txt.

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

1. Abstract

This Internet-Draft will expire on February 3, 2006.

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 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 [RFC-2119].

3. RFC2119 [1].

2. Introduction

Routers and destination hosts

IP routers use the Internet Control Message Protocol (ICMP) [RFC-792] [2] to
convey control information to source hosts. Network operators use
this information to diagnose routing problems.

Bonica, Tappan, Hwa Draft-Expires February 2001 1

When a router receives an undeliverable IP datagram, it can send an
ICMP message to the host that originated the datagram. The ICMP
message indicates why the datagram could not be delivered. It also
contains the IP header and leading payload octets of the "original
datagram".

In this document, the term "original datagram" refers to the datagram
to which the ICMP message is a response.

MPLS Label Switching Routers (LSR) also use ICMP to convey control
information to source hosts. Sections 2.3 and 2.4 of [ENCODE] RFC 3032 [3]
describe the interaction between MPLS and ICMP.

When an LSR receives an undeliverable MPLS encapsulated datagram, it
removes the entire MPLS label stack, exposing the previously
encapsulated IP datagram. The LSR then submits the IP datagram to a
network-forwarding module for an
error processing. processing module. Error processing can include ICMP message
generation.

The ICMP message indicates why the original datagram could not be
delivered. It also contains the IP header and leading octets of the
original datagram.

The ICMP message, however, includes contains no information regarding the MPLS
label stack that encapsulated the original datagram when it arrived
at the LSR. This omission is significant because the LSR would have
routed the original datagram based upon information contained by the
MPLS label stack.

The current

This memo proposes extensions to ICMP that permit an LSR to append
MPLS label stack information to ICMP messages. ICMP messages
regarding MPLS encapsulated datagrams 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 IP header and leading payload
octets of the original datagram.

Network operators will use this information

3. Application to diagnose routing
problems.

4. Motivation TRACEROUTE

ICMP extensions defined in the current this memo support enhancements to
TRACEROUTE. The enhanced TRACEROUTE, like older implementations,
indicates which nodes the original datagram visited en route to its
ultimate
destination. It differs from older implementations in that it also
indicates the original datagrams MPLS encapsulation status as it
arrived at each node.

Figure 1 contains sample output from an enhanced TRACEROUTE
implementation.

Bonica,Tappan,Gan Draft-Expires February 2001 2
>Traceroute 166.45.2.74

> traceroute 100.100.6.1

traceroute to 166.45.2.74, 100.100.6.1 (100.100.6.1), 30 hops max, 40 byte packets

1 166.45.5.1 1.281 10.1.1.2 (10.1.1.2) 0.661 ms 1.103 0.618 ms 1.096 0.579 ms

2 166.45.4.1 1.281 10.1.12.2 (10.1.12.2) 0.861 ms 1.103 0.718 ms 1.096 0.679 ms mplsLabel1=2001
mplsExpBits1=0

MPLS Label=100048 Exp=0 TTL=1 S=1

3 166.45.3.1 1.281 10.1.24.2 (10.1.24.2) 0.822 ms 1.103 0.731 ms 1.096 0.708 ms mplsLabel1=2002
mplsExpBits1=0

MPLS Label=100016 Exp=0 TTL=1 S=1

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 10.100.6.1 (10.100.6.1) 0.961 ms 1.096 8.676 ms
6 166.45.2.74 1.281 ms 1.103 ms 1.096 0.875 ms

Figure 1. 1: Enhanced TRACEROUTE sample output

5. Sample Output

4. Disclaimer

The current

This memo does not define the general relationship between ICMP and
MPLS. Sections 2.3 and 2.4 of [ENCODE] RFC3032 define this relationship.

Specifically, this document defers to [ENCODE] RFC3032 with respect to the
following issues:

- conditions upon which an LSR emits ICMP messages

- handling of ICMP messages bound for hosts that are identified by
private addresses

The current memo does not define encapsulation specific TTL
manipulation procedures. It defers to Section 10 5.4 of [MPLSATM] RFC 3034 [4]
and Section 5.4 10 of [MPLSFRAME] RFC 3035 [5] in this matter.

When encapsulation specific TTL manipulation procedures defeat the
basic TRACEROUTE mechanism, they will also defeat enhanced TRACEROUTE
implementations.

The current memo does not address extensions to ICMPv6. These should
be addressed in a separate draft.

6. Formal

5. Syntax

This section defines a data structure that an LSR can append to
selected ICMP messages. The data structure contains the MPLS label
stack that encapsulated the original datagram when it arrived at the
LSR.

The

In theory, the data structure defined herein can be appended to the
following ICMP message types:

Bonica,Tappan,Gan Draft-Expires February 2001 3
1)

Destination Unreachable
2)

Time Exceeded
3)

Parameter Problem
4)

Source Quench
5)

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
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
24 through 27 contain message specific data.

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
IP header and leading 64 bits of the original datagram. [RFC-1812] RFC 1812 [6]
recommends that this final field be extended to include as much of
the original datagram as possible.

When an LSR appends the data structure defined herein to an ICMP
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
octets represent the IP header of the original datagram.

If the original datagram was shorter than 128 octets, the final field
MUST be padded with 0's.

When an LSR appends the data structure defined herein to an ICMP
message, the ICMP "total length" MUST be equal adjusted appropriately to
include the data structure
length plus 156. The first octet of the data structure must be
displaced 156 octets from the beginning of the ICMP message. structure.

The data structure defined in this section consists of a common
header followed by object instances. Each object instance consists
of an object header plus contents.

Currently, two object classes are defined. One object class contains
an entire MPLS label stack, formatted exactly as it was when it
arrived at the LSR that sends the ICMP message. The other contains
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
beyond).

Both object classes are optional.

In the future, additional object classes may be defined.

Bonica,Tappan,Gan Draft-Expires February 2001 4

6.1

5.1 Common Header

0 1 2 3
+-------------+-------------+-------------+-------------+
| Vers | (Reserved) | Checksum |
+-------------+-------------+-------------+-------------+

Figure 2: Common Header

The fields in the common header are as follows:

Vers: 4 bits

ICMP extension version number. This is version 2.

Checksum: 16 bits

The one's complement of the one's complement sum of the data
structure, with the checksum field replaced by zero for the
purpose of computing the checksum. An all-zero value means that
no checksum was transmitted.

If the checksum field contains a value other than described above,
the ICMP message does not include the extensions described in this
memo. This, however, does not imply that the ICMP message is
malformed. It may be in strict compliance with RFC-1812.

Reserved: Must be set to 0.

6.2

5.2 Object Header

Every object consists of one or more 32-bit words with a one-word
header, with the
header. The following format: is the format of the one-word header:

+-------------+-------------+-------------+-------------+
| Length | Class-Num | C-Type |
+-------------+-------------+-------------+-------------+
| |
| // (Object contents) // |
| |
+-------------+-------------+-------------+-------------+

Figure 3: Object Header

An object header has the following fields:

Length: 16 bits

Length of the object, measured in octets, including the object
header and object contents.
Bonica,Tappan,Gan Draft-Expires February 2001 5

Class-Num: 8 bits

Identifies object class.

C-Type: 8 bits

Identifies object sub-type.

6.3

5.3 MPLS Stack Entry Object Class

A single instance of the MPLS Entry Object class represents the
entire MPLS label stack, formatted exactly as it was when it arrived
at the LSR that sends the ICMP message

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
represented by another 4 octets that share the same format.

Syntax follows:

MPLS Stack Entry Class = 1, C-Type = 1.

0 1 2 3
+-------------+-------------+-------------+-------------+
| Label |EXP |S| TTL |
+-------------+-------------+-------------+-------------+
| |
| // Remaining MPLS Stack Entries // |
| |
+-------------+-------------+-------------+-------------+

Figure 4: MPLS Stack Entry Object Class

Label: 20 bits

Exp: Experimental Use, 3 bits

S: Bottom of Stack, 1 bit

TTL: Time to Live, 8 bits

6.4

5.4 Extended Payload Object Class

An instance of the Extended Payload Object class represents some
portion of the original datagram that could not be fit in the final
field of the ICMP message body (i.e., octets beyond 128).

Bonica,Tappan,Gan Draft-Expires February 2001 6

Syntax follows:

MPLS Stack Entry Class = 2, C-Type = 1.

0 1 2 3
+-------------+-------------+-------------+-------------+
| |
| // Additional bytes of original datagram // |
| |
+-------------+-------------+-------------+-------------+

Figure 5: Extended Payload Object Class

6. Backward Compatibility

ICMP extensions proposed in this document MUST be backward compatible
with the syntax described in RFC-792. Extensions proposed in this
memo MUST NOT change or deprecate any field defined in RFC-
792. RFC-792.

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-
1812 extends the final field of selected ICMP messages to include a
greater portion of the original datagram. Unfortunately, it extends
this field to a variable length without adding a length attribute.

This memo binds the length of that final field to an arbitrarily
large value (128 octets). Fixing the length of that field
facilitates extension of the ICMP message. An additional object is
provided through which octets 129 and beyond can be appended to the
ICMP message.

As few datagrams contain L3 or L4 header information beyond octet
128, it is unlikely that the extensions described herein will disable
any applications that rely upon RFC-1812 style ICMP messages.

7. Security Considerations

This memo presents no security considerations beyond those already
presented by current ICMP applications (e.g., traceroute).

9. References

[ARCH], Rosen, E., Viswanathan, A.,

8. IANA Considerations

IANA should establish a registry of ICMP extention classes and R. Callon, "Multiprotocol
Label Switching Architecture", Internet Draft <draft-ietf-mpls-arch-
06.txt>, August, 1999

Bonica,Tappan,Gan Draft-Expires February 2001 7
[ENCODE], class-
sub-types.

9. Normative References

[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.

[2] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792,
September 1981.

[3] Rosen, E., Rekhter, Y., Tappan, D, Farinacci, D., Fedorkow, G., Rekhter, Y., Farinacci, D.,
Li, T., and A. Conta, A., "MPLS Label Stack Encoding", Internet
Draft, <draft-ietf-mpls-label-encapse-07.txt>, September 1999.

[MPLSATM], RFC 3032,
January 2001.

[4] Conta, A., Doolan, P., and A. Malis, "Use of Label Switching on
Frame Relay Networks Specification", RFC 3034, January 2001.

[5] Davie, B., Lawrence, J., McCloghrie, K., Rekhter, Y., Rosen, E., Swallow, G, G.,
Rekhter, Y., and P. Doolan, "MPLS using LDP and ATM VC
Switching",
<draft-ietf- mpls-atm-04.txt>, June 2000.

[MPLSFRAME], Conta, A., Doolan, P., Malis, A., "Use of Label
Switching on Frame Relay Networks", <draft-ietf-mpls-fr-06.txt>,
June, 2000.

[RFC-792], Postel, J., "Internet Control Message Protocol", RFC 792,
ISI, September 1981.

[RFC-1812], 3035, January 2001.

[6] Baker, F., "Requirements for IP Version 4 Routers", RFC 1812,
June 1995.

[RFC-2026], Bradner, S., "Internet Standards Process Revision 3",
RFC 2026, Harvard University, October 1996.

[RFC-2119], Bradner, S,, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, Harvard University, March 1997

10. Acknowledgments

Thanks to Yakov Rekhter and Mike Heard for their contributions to
this memo.

11. Author's

Authors' Addresses

Ronald P. Bonica
MCI WorldCom
22001 Loudoun County Pkwy
Ashburn, Virginia, 20147
Phone: 703 886 1681
Juniper Networks
2251 Corporate Park Drive
Herndon, VA 20171
US

Email: rbonica@mci.net rbonica@juniper.net

Der-Hwa Gan
Juniper Networks
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US

Email: dhg@juniper.net
Daniel C. Tappan
Cisco Systems Systems, Inc.
250 Apollo Drive
Chelmsford, Massachusetts, MA 01824
US

Email: tappan@cisco.com

Der-Hwa Gan
Juniper Networks
385 Ravendale Drive
Mountain View, California 94043
Bonica,Tappan,Gan Draft-Expires February 2001 8
Email: dhg@juniper.net

Bonica,Tappan,Gan Draft-Expires February 2001 9

Full Copyright

Intellectual Property Statement

"Copyright (C)

The Internet Society (date). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on IETF takes no position regarding the validity or otherwise explain it scope of any
Intellectual Property Rights or assist in its implmentation may other rights that might be prepared, copied, published
and distributed, in whole claimed to
pertain to the implementation or in part, without restriction use of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, technology described in
this document itself may or the extent to which any license under such rights
might or might not be modified in available; nor does it represent that it has
made any independent effort to identify any way, such as by removing rights. Information
on the copyright notice procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.

Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or references the result of an
attempt made to obtain a general license or permission for the Internet Society use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.

The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other
Internet organizations, except as needed for proprietary
rights that may cover technology that may be required to implement
this standard. Please address the purpose information to the IETF at
ietf-ipr@ietf.org.

Disclaimer of
developing Validity

This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Copyright (C) The Internet standards Society (2005). This document is subject
to the rights, licenses and restrictions contained in which case BCP 78, and
except as set forth therein, the procedures authors retain all their rights.

Acknowledgment

Funding for
copyrights defined in the RFC Editor function is currently provided by the
Internet Standards process must be
followed, or as required to translate it into

Bonica,Tappan,Gan Draft-Expires February 2001 10 Society.