wdiff rfc5711.alt-original rfc5711.txt

Networking Working Group
Internet Engineering Task Force (IETF) JP. Vasseur, Ed.
Internet-Draft George.
Request for Comments: 5711 G. Swallow
Intended status:
Category: Standards Track Cisco Systems, Inc
Expires: April 1, 2010 Ina. Inc.
ISSN: 2070-1721 I. Minei
Juniper Networks
September 28, 2009
January 2010

Node behavior Behavior upon originating Originating and receiving Receiving Resource ReserVation Reservation
Protocol (RSVP) Path Error message
draft-ietf-mpls-3209-patherr-06.txt Messages

Abstract

The aim of this document is to describe a common practice with regard
to the behavior of a node sending nodes that send and receive a Resource ReserVation Reservation
Protocol (RSVP) Traffic Engineering (TE) Path Error message and to the
behavior of a node receiving an RSVP Path Error message messages for a
preempted Multi-Protocol Multiprotocol Label Switching (MPLS) and or Generalized MPLS
(GMPLS) Traffic Engineering Label Switched Path (TE LSP). (For
reference to the notion of TE LSP preemption, see RFC 3209.) This
document does not define any new protocol extensions.

Status of this This Memo

This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.

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The list Section 2 of RFC 5741.

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This Internet-Draft will expire on April 1, 2010.
http://www.rfc-editor.org/info/rfc5711.

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Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are to be interpreted provided without warranty as
described in RFC 2119 [RFC2119]. the Simplified BSD License.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 ....................................................3
1.1. Requirements Language ......................................3
2. Protocol behavior . . . . . . . . . . . . . . . . . . . . . . . 3 Behavior ...............................................3
2.1. Behavior at Detecting Nodes . . . . . . . . . . . . . . . . 4 ................................4
2.2. Behavior at Receiving Nodes . . . . . . . . . . . . . . . . 4 ................................5
2.3. Data Plane Data-Plane Behavior . . . . . . . . . . . . . . . . . . . . 5 ........................................5
3. RSVP PathErr Messages For for a Preempted TE LSP . . . . . . . . . 5 ....................5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
6. .........................................5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
7. ................................................6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. ......................................................6
6.1. Normative References . . . . . . . . . . . . . . . . . . . 6
7.2. .......................................6
6.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 .....................................6

1. Introduction

The aim of this document is to describe a common practice with regard
to the behavior of a node sending a Resource ReserVation Reservation Protocol
(RSVP) Traffic Engineering (TE) Path Error message and to the
behavior of a node receiving an RSVP Path Error message for a
preempted Multi-Protocol Multiprotocol Label Switching (MPLS) and Generalized MPLS
(GMPLS) Traffic Engineering Label Switched Path (TE LSP) (for LSP). (For
reference to the notion of TE LSP preemption preemption, see [RFC3209]).

[RFC2205] defines two RSVP error message types: PathErr and ResvErr
that are generated when an error occurs. Path Error Messages messages
(PathErr) are used to report errors and travel upstream toward the
head-end of the flow. Resv Error messages (ResvErr) travel
downstream toward the tail-end of the flow.

This document describes only PathErr message processing for the
specific case of a preempted Traffic Engineering Label Switched Path
(TE LSP) TE LSP, where the term preemption is
defined in [RFC3209].

1.1. Requirements Language

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 [RFC2119].

2. Protocol behavior Behavior

PathErr messages are routed hop-by-hop using the path state
established when a Path message is routed through the network from
the head-end to its tail-end.

As stated in [RFC2205], PathErr messages do not modify the state of
any node through which they pass; they are only reported to the head-
end of the TE LSP (Traffic Engineering Label Switched Path).

The format of the PathErr message is defined in Section 3. of
[RFC2205].

The ERROR_SPEC object includes the IP address of the node that
detected the error (Error Node Address), and specifies the error
through two fields. The Error Code field encodes the category of the
error, for example, Policy Control Failure or Unknown object class.
The Error Value field qualifies the error code to indicate the error
with more precision. [RFC3209] extends RSVP as defined in [RFC2205]
for the management of Multi-Protocol Label Switching (MPLS) Traffic
Engineered Label Switched Paths (TE-LSPs). MPLS-TE LSPs. [RFC3209] specifies several
additional conditions that trigger the sending of a RSVP PathErr
message for which new error codes and error values have been defined
that extend the list defined in [RFC2205]. The exact circumstances
under which a TE LSP is preempted and such PathErr messages are sent
are defined in Section 2.2 of [RFC3209] and will not be repeated here.

Values for the Error Code and Error Value fields defined in
[RFC2205], [RFC3209], and other documents are maintained in a
registry by the IANA.

The error conditions fall into two categories:

o Fatal errors represent disruptive conditions for a TE LSP, LSP.

o Non-fatal errors are non-disruptive conditions which that have occurred
for this TE LSP LSP.

PathErr messages may be used in two circumstances:

o During during TE LSP establishment, and

o After after a TE LSP has been successfully established.

Nodal behavior is dependent on which combination of the four cases
listed above applies. The following sections describe the expected
behavior at nodes that perform a preemption action for a TE LSP (and
therefore report using error PathErr messages), and at nodes that
receive PathErr messages. This text is a clarification and re-
statement
restatement of the procedures set out in [RFC3209] and does not
define any new behavior.

2.1. Behavior at Detecting Nodes

In the case of fatal errors ("Hard Preemption" Preemption"; see section Section 4.7.3 of
[RFC3209]),
[RFC3209] ), the detecting node SHOULD MUST send a PathErr message reporting
the error condition, and clears MUST clear the corresponding Path and Resv
(control plane) states. A direct implication is that the data
plane data-plane
resources of such a TE LSP are also released, thus resulting in
traffic disruption. It should be noted, however, that in fatal error
cases, the LSP has usually already failed in the data plane, and
traffic has already been disrupted. When the error arises during LSP
establishment, the implications are different to when it arises on an
active LSP since no traffic flows until the LSP has been fully
established. In the case of non-fatal errors, the detecting node
should send a PathErr message, and must not clear control plane or
data plane state.

2.2. Behavior at Receiving Nodes

Nodes that receive PathErr messages are all of the nodes along the
path of the TE LSP upstream of the node that detected the error.
This includes the head-end node. In accordance with [RFC2205] Section 3.7.1, 3.7.1 of
[RFC2205], a node receiving a PathErr message takes no action upon it
it, and consequently it the node must not clear Path or Resv control control-
plane or data plane data-plane state. This is true regardless of whether the
error condition reported by the PathErr is fatal or non-fatal. RSVP
states should only be affected upon receiving a PathTear or ResvTear
message, or in the event of a Path or Resv state timeout. Further
discussion of the processing of these events is outside the scope of
this document.

Note that [RFC3473] defines a Path_State_Removed flag in the
ERROR_SPEC object carried on a PathErr message. This field may be
set to change the behavior of upstream nodes that receive the PathErr
message. When set, the flag indicates that the message sender has
removed Path state (and any associated Resv and data plane data-plane state) for
the TE LSP. The message receiver should do likewise before
forwarding the message, but may retain state and clear the flag
before forwarding the message.

2.3. Data Plane Data-Plane Behavior

Any node clearing either or both the Path or the Resv state of a TE
LSP MUST also free up the data plane data-plane resources allocated to the
corresponding TE LSP.

3. RSVP PathErr Messages For for a Preempted TE LSP

Two Error-code Error Codes have been defined to report a preempted TE LSP:

o As defined in [RFC2750]:Error [RFC2750]: Error Code=2: "Policy Control Failure",
Error Value=5 Value=5: "Flow was preempted"

o As defined in [RFC2205], Error Code=12: "Service preempted"

In both cases, these

They are both fatal errors.

4. IANA Considerations

This document does not define any new protocol extensions and thus no
action is requested to IANA.

5. Security Considerations

This document does not define any new procedures, but clarifies those
defined in other documents where security considerations are already
specified in [RFC3209] and [RFC3473]. This document does not raise
specific security issues beyond those of existing MPLS-TE. By
clarifying the procedures, this document reduces the security risk
introduced by non-conformant implementations. See
[I-D.ietf-mpls-mpls-and-gmpls-security-framework] [SEC_FMWK] for
further discussion of MPLS security issues.

5. Acknowledgements

The author authors would like to thank Carol Iturralde, Ashok Narayanan, Rom
Reuther
Reuther, and Reshad Rahman.

6. References

7.1.

6.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.

[RFC2750] Herzog, S., "RSVP Extensions for Policy Control",
RFC 2750, January 2000.

[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.

[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473,
January 2003.

7.2.

6.2. Informative References

[I-D.ietf-mpls-mpls-and-gmpls-security-framework]

[SEC_FMWK] Fang, L. and M. Behringer, L., Ed., "Security Framework for MPLS and GMPLS
Networks",
draft-ietf-mpls-mpls-and-gmpls-security-framework-06 (work Work in progress), July Progress, October 2009.

Authors' Addresses

JP Vasseur (editor)
Cisco Systems, Inc Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719
USA

Email:

EMail: jpv@cisco.com

George Swallow
Cisco Systems, Inc Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719
USA

Email:

EMail: swallow@cisco.com

Ina Minei
Juniper Networks
1194 North Mathilda Ave.
Sunnyvale, CA 94089

Email:
USA

EMail: ina@juniper.net