draft-ietf-mpls-3209-patherr-06.txt   rfc5711.txt 
Networking Working Group JP. Vasseur, Ed. Internet Engineering Task Force (IETF) JP. Vasseur, Ed.
Internet-Draft George. Swallow Request for Comments: 5711 G. Swallow
Intended status: Standards Track Cisco Systems, Inc Updates: 3209 Cisco Systems, Inc.
Expires: April 1, 2010 Ina. Minei Category: Standards Track I. Minei
Juniper Networks ISSN: 2070-1721 Juniper Networks
September 28, 2009 January 2010
Node behavior upon originating and receiving Resource ReserVation
Protocol (RSVP) Path Error message
draft-ietf-mpls-3209-patherr-06.txt
Status of this Memo Node Behavior upon Originating and Receiving Resource Reservation
Protocol (RSVP) Path Error Messages
This Internet-Draft is submitted to IETF in full conformance with the Abstract
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering The aim of this document is to describe a common practice with regard
Task Force (IETF), its areas, and its working groups. Note that to the behavior of nodes that send and receive a Resource Reservation
other groups may also distribute working documents as Internet- Protocol (RSVP) Traffic Engineering (TE) Path Error messages for a
Drafts. preempted Multiprotocol Label Switching (MPLS) 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.
Internet-Drafts are draft documents valid for a maximum of six months Status of This Memo
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 This is an Internet Standards Track document.
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at This document is a product of the Internet Engineering Task Force
http://www.ietf.org/shadow.html. (IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on April 1, 2010. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc5711.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of Provisions Relating to IETF Documents
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Please review these documents carefully, as they describe your rights publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
Abstract include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
The aim of this document is to describe a common practice with regard described in the Simplified BSD License.
to the behavior of a node sending a Resource 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 Label Switching (MPLS) and Generalized MPLS
(GMPLS) Traffic Engineering Label Switched Path (TE LSP). This
document does not define any new protocol extensions.
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].
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................3
2. Protocol behavior . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language ......................................3
2.1. Behavior at Detecting Nodes . . . . . . . . . . . . . . . . 4 2. Protocol Behavior ...............................................3
2.2. Behavior at Receiving Nodes . . . . . . . . . . . . . . . . 4 2.1. Behavior at Detecting Nodes ................................4
2.3. Data Plane Behavior . . . . . . . . . . . . . . . . . . . . 5 2.2. Behavior at Receiving Nodes ................................5
3. RSVP PathErr Messages For a Preempted TE LSP . . . . . . . . . 5 2.3. Data-Plane Behavior ........................................5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 3. RSVP PathErr Messages for a Preempted TE LSP ....................5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations .........................................5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 5. Acknowledgements ................................................6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6. References ......................................................6
7.1. Normative References . . . . . . . . . . . . . . . . . . . 6 6.1. Normative References .......................................6
7.2. Informative References . . . . . . . . . . . . . . . . . . 6 6.2. Informative References .....................................6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
The aim of this document is to describe a common practice with regard The aim of this document is to describe a common practice with regard
to the behavior of a node sending a Resource ReserVation Protocol to the behavior of a node sending a Resource Reservation Protocol
(RSVP) Traffic Engineering (TE) Path Error message and to the (RSVP) Traffic Engineering (TE) Path Error message and to the
behavior of a node receiving an RSVP Path Error message for a behavior of a node receiving an RSVP Path Error message for a
preempted Multi-Protocol Label Switching (MPLS) and Generalized MPLS preempted Multiprotocol Label Switching (MPLS) and Generalized MPLS
(GMPLS) Traffic Engineering Label Switched Path (TE LSP) (for (GMPLS) Traffic Engineering Label Switched Path (TE LSP). (For
reference to the notion of TE LSP preemption see [RFC3209]). reference to the notion of TE LSP preemption, see [RFC3209]).
[RFC2205] defines two RSVP error message types: PathErr and ResvErr [RFC2205] defines two RSVP error message types: PathErr and ResvErr
that are generated when an error occurs. Path Error Messages that are generated when an error occurs. Path Error messages
(PathErr) are used to report errors and travel upstream toward the (PathErr) are used to report errors and travel upstream toward the
head-end of the flow. Resv Error messages (ResvErr) travel head-end of the flow. Resv Error messages (ResvErr) travel
downstream toward the tail-end of the flow. downstream toward the tail-end of the flow.
This document describes only PathErr message processing for the This document describes only PathErr message processing for the
specific case of a preempted Traffic Engineering Label Switched Path specific case of a preempted TE LSP, where the term preemption is
(TE LSP) where the term preemption is defined in [RFC3209]. defined in [RFC3209].
2. Protocol behavior 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
PathErr messages are routed hop-by-hop using the path state PathErr messages are routed hop-by-hop using the path state
established when a Path message is routed through the network from established when a Path message is routed through the network from
the head-end to its tail-end. the head-end to its tail-end.
As stated in [RFC2205], PathErr messages do not modify the state of 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- any node through which they pass; they are only reported to the head-
end of the TE LSP (Traffic Engineering Label Switched Path). end of the TE LSP (Traffic Engineering Label Switched Path).
The format of the PathErr message is defined in Section 3. of The format of the PathErr message is defined in Section 3. of
[RFC2205]. [RFC2205].
The ERROR_SPEC object includes the IP address of the node that The ERROR_SPEC object includes the IP address of the node that
detected the error (Error Node Address), and specifies the error detected the error (Error Node Address), and specifies the error
through two fields. The Error Code field encodes the category of the through two fields. The Error Code field encodes the category of the
error, for example, Policy Control Failure or Unknown object class. error, for example, Policy Control Failure or Unknown object class.
The Error Value field qualifies the error code to indicate the error The Error Value field qualifies the error code to indicate the error
with more precision. [RFC3209] extends RSVP as defined in [RFC2205] with more precision. [RFC3209] extends RSVP as defined in [RFC2205]
for the management of Multi-Protocol Label Switching (MPLS) Traffic for the management of MPLS-TE LSPs. [RFC3209] specifies several
Engineered Label Switched Paths (TE-LSPs). [RFC3209] specifies additional conditions that trigger the sending of a RSVP PathErr
several additional conditions that trigger the sending of a RSVP message for which new error codes and error values have been defined
PathErr message for which new error codes and error values have been that extend the list defined in [RFC2205]. The exact circumstances
defined that extend the list defined in [RFC2205]. The exact under which a TE LSP is preempted and such PathErr messages are sent
circumstances under which a TE LSP is preempted and such PathErr are defined in [RFC3209] and will not be repeated here.
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 Values for the Error Code and Error Value fields defined in
[RFC2205], [RFC3209], and other documents are maintained in a [RFC2205], [RFC3209], and other documents are maintained in a
registry by the IANA. registry by the IANA.
The error conditions fall into two categories: The error conditions fall into two categories:
o Fatal errors represent disruptive conditions for a TE LSP, o Fatal errors represent disruptive conditions for a TE LSP.
o Non-fatal errors are non-disruptive conditions which have occurred o Non-fatal errors are non-disruptive conditions that have occurred
for this TE LSP for this TE LSP.
PathErr messages may be used in two circumstances: PathErr messages may be used in two circumstances:
o During TE LSP establishment, o during TE LSP establishment, and
o After a TE LSP has been successfully established. o after a TE LSP has been successfully established.
Nodal behavior is dependent on which combination of the four cases Nodal behavior is dependent on which combination of the four cases
listed above applies. The following sections describe the expected listed above applies. The following sections describe the expected
behavior at nodes that perform a preemption action for a TE LSP (and behavior at nodes that perform a preemption action for a TE LSP (and
therefore report using error PathErr messages), and at nodes that therefore report using error PathErr messages), and at nodes that
receive PathErr messages. This text is a clarification and re- receive PathErr messages. This text is a clarification and
statement of the procedures set out in [RFC3209] and does not define restatement of the procedures set out in [RFC3209] and does not
any new behavior. define any new behavior.
2.1. Behavior at Detecting Nodes 2.1. Behavior at Detecting Nodes
In the case of fatal errors ("Hard Preemption" see section 4.7.3 of In the case of fatal errors ("Hard Preemption"; see Section 4.7.3 of
[RFC3209]), the detecting node SHOULD send a PathErr message [RFC3209] ), the detecting node MUST send a PathErr message reporting
reporting the error condition, and clears the corresponding Path and the error condition, and MUST clear the corresponding Path and Resv
Resv (control plane) states. A direct implication is that the data (control plane) states. A direct implication is that the data-plane
plane resources of such a TE LSP are also released, thus resulting in resources of such a TE LSP are also released, thus resulting in
traffic disruption. It should be noted, however, that in fatal error traffic disruption. It should be noted, however, that in fatal error
cases, the LSP has usually already failed in the data plane, and cases, the LSP has usually already failed in the data plane, and
traffic has already been disrupted. When the error arises during LSP traffic has already been disrupted. When the error arises during LSP
establishment, the implications are different to when it arises on an establishment, the implications are different to when it arises on an
active LSP since no traffic flows until the LSP has been fully active LSP since no traffic flows until the LSP has been fully
established. In the case of non-fatal errors, the detecting node established. In the case of non-fatal errors, the detecting node
should send a PathErr message, and must not clear control plane or should send a PathErr message, and must not clear control plane or
data plane state. data plane state.
2.2. Behavior at Receiving Nodes 2.2. Behavior at Receiving Nodes
Nodes that receive PathErr messages are all of the nodes along the 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. path of the TE LSP upstream of the node that detected the error.
This includes the head-end node. In accordance with [RFC2205] This includes the head-end node. In accordance with Section 3.7.1 of
Section 3.7.1, a node receiving a PathErr message takes no action [RFC2205], a node receiving a PathErr message takes no action upon
upon it and consequently it must not clear Path or Resv control plane it, and consequently the node must not clear Path or Resv control-
or data plane state. This is true regardless of whether the error plane or data-plane state. This is true regardless of whether the
condition reported by the PathErr is fatal or non-fatal. RSVP states error condition reported by the PathErr is fatal or non-fatal. RSVP
should only be affected upon receiving a PathTear or ResvTear states should only be affected upon receiving a PathTear or ResvTear
message, or in the event of a Path or Resv state timeout. Further 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 discussion of the processing of these events is outside the scope of
this document. this document.
Note that [RFC3473] defines a Path_State_Removed flag in the Note that [RFC3473] defines a Path_State_Removed flag in the
ERROR_SPEC object carried on a PathErr message. This field may be ERROR_SPEC object carried on a PathErr message. This field may be
set to change the behavior of upstream nodes that receive the PathErr set to change the behavior of upstream nodes that receive the PathErr
message. When set, the flag indicates that the message sender has message. When set, the flag indicates that the message sender has
removed Path state (and any associated Resv and data plane state) for removed Path state (and any associated Resv and data-plane state) for
the TE LSP. The message receiver should do likewise before the TE LSP. The message receiver should do likewise before
forwarding the message, but may retain state and clear the flag forwarding the message, but may retain state and clear the flag
before forwarding the message. before forwarding the message.
2.3. Data Plane Behavior 2.3. Data-Plane Behavior
Any node clearing either or both the Path or the Resv state of a TE Any node clearing either or both the Path or the Resv state of a TE
LSP MUST also free up the data plane resources allocated to the LSP MUST also free up the data-plane resources allocated to the
corresponding TE LSP. corresponding TE LSP.
3. RSVP PathErr Messages For a Preempted TE LSP 3. RSVP PathErr Messages for a Preempted TE LSP
Two Error-code have been defined to report a preempted TE LSP: Two Error Codes have been defined to report a preempted TE LSP:
o As defined in [RFC2750]:Error Code=2: "Policy Control Failure", o As defined in [RFC2750]: Error Code=2: "Policy Control Failure",
Error Value=5 "Flow was preempted" Error Value=5: "Flow was preempted"
o As defined in [RFC2205], Error Code=12: "Service preempted" o As defined in [RFC2205], Error Code=12: "Service preempted"
In both cases, these are fatal errors. 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 4. Security Considerations
This document does not define any new procedures, but clarifies those This document does not define any new procedures, but clarifies those
defined in other documents where security considerations are already defined in other documents where security considerations are already
specified in [RFC3209] and [RFC3473]. This document does not raise specified in [RFC3209] and [RFC3473]. This document does not raise
specific security issues beyond those of existing MPLS-TE. By specific security issues beyond those of existing MPLS-TE. By
clarifying the procedures, this document reduces the security risk clarifying the procedures, this document reduces the security risk
introduced by non-conformant implementations. See introduced by non-conformant implementations. See [SEC_FMWK] for
[I-D.ietf-mpls-mpls-and-gmpls-security-framework] for further further discussion of MPLS security issues.
discussion of MPLS security issues.
6. Acknowledgements 5. Acknowledgements
The author would like to thank Carol Iturralde, Ashok Narayanan, Rom The authors would like to thank Carol Iturralde, Ashok Narayanan, Rom
Reuther and Reshad Rahman. Reuther, and Reshad Rahman.
7. References 6. References
7.1. Normative References 6.1. Normative References
[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.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. [RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997. Functional Specification", RFC 2205, September 1997.
[RFC2750] Herzog, S., "RSVP Extensions for Policy Control", [RFC2750] Herzog, S., "RSVP Extensions for Policy Control",
RFC 2750, January 2000. RFC 2750, January 2000.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001. Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic (GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. Engineering (RSVP-TE) Extensions", RFC 3473,
January 2003.
7.2. Informative References 6.2. Informative References
[I-D.ietf-mpls-mpls-and-gmpls-security-framework] [SEC_FMWK] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Fang, L. and M. Behringer, "Security Framework for MPLS Networks", Work in Progress, October 2009.
and GMPLS Networks",
draft-ietf-mpls-mpls-and-gmpls-security-framework-06 (work
in progress), July 2009.
Authors' Addresses Authors' Addresses
JP Vasseur (editor) JP Vasseur (editor)
Cisco Systems, Inc Cisco Systems, Inc.
1414 Massachusetts Avenue 1414 Massachusetts Avenue
Boxborough, MA 01719 Boxborough, MA 01719
USA USA
Email: jpv@cisco.com EMail: jpv@cisco.com
George Swallow George Swallow
Cisco Systems, Inc Cisco Systems, Inc.
1414 Massachusetts Avenue 1414 Massachusetts Avenue
Boxborough, MA 01719 Boxborough, MA 01719
USA USA
Email: swallow@cisco.com EMail: swallow@cisco.com
Ina Minei Ina Minei
Juniper Networks Juniper Networks
1194 North Mathilda Ave. 1194 North Mathilda Ave.
Sunnyvale, 94089 Sunnyvale, CA 94089
USA
Email: ina@juniper.net EMail: ina@juniper.net
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