draft-ietf-mpls-3209-patherr-05.txt   draft-ietf-mpls-3209-patherr-06.txt 
Networking Working Group JP. Vasseur, Ed. Networking Working Group JP. Vasseur, Ed.
Internet-Draft George. Swallow Internet-Draft George. Swallow
Intended status: BCP Cisco Systems, Inc Intended status: Standards Track Cisco Systems, Inc
Expires: January 30, 2010 Ina. Minei Expires: April 1, 2010 Ina. Minei
Juniper Networks Juniper Networks
July 29, 2009 September 28, 2009
Node behavior upon originating and receiving Resource ReserVation Node behavior upon originating and receiving Resource ReserVation
Protocol (RSVP) Path Error message Protocol (RSVP) Path Error message
draft-ietf-mpls-3209-patherr-05.txt draft-ietf-mpls-3209-patherr-06.txt
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on January 30, 2010. This Internet-Draft will expire on April 1, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 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 in effect on the date of
publication of this document (http://trustee.ietf.org/license-info). publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol behavior . . . . . . . . . . . . . . . . . . . . . . . 3 2. Protocol behavior . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Behavior at Detecting Nodes . . . . . . . . . . . . . . . . 4 2.1. Behavior at Detecting Nodes . . . . . . . . . . . . . . . . 4
2.2. Behavior at Receiving Nodes . . . . . . . . . . . . . . . . 4 2.2. Behavior at Receiving Nodes . . . . . . . . . . . . . . . . 4
2.3. Data Plane Behavior . . . . . . . . . . . . . . . . . . . . 5 2.3. Data Plane Behavior . . . . . . . . . . . . . . . . . . . . 5
3. RSVP PathErr Messages For a Preempted TE LSP . . . . . . . . . 5 3. RSVP PathErr Messages For a Preempted TE LSP . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 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 Multi-Protocol Label Switching (MPLS) and Generalized MPLS
(GMPLS) Traffic Engineering Label Switched Path (TE LSP). (GMPLS) Traffic Engineering Label Switched Path (TE LSP) (for
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 Traffic Engineering Label Switched Path
(TE LSP) where the term preemption is defined in [RFC3209]. (TE LSP) where the term preemption is defined in [RFC3209].
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2. Protocol behavior 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 as defined in [RFC2205]. 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 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 Multi-Protocol Label Switching (MPLS) Traffic
Engineered Label Switched Paths (TE-LSPs). [RFC3209] specifies Engineered Label Switched Paths (TE-LSPs). [RFC3209] specifies
several additional conditions that trigger the sending of a RSVP several additional conditions that trigger the sending of a RSVP
PathErr message for which new error codes and error values have been PathErr message for which new error codes and error values have been
defined that extend the list defined in [RFC2205]. The exact defined that extend the list defined in [RFC2205]. The exact
circumstances under which a TE LSP is preempted and such PathErr circumstances under which a TE LSP is preempted and such PathErr
messages are sent are defined in [RFC3209] and will not be repeated messages are sent are defined in Section 2.2 of [RFC3209] and will
here. 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 which have occurred
for this TE LSP for this TE LSP
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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 re-
statement of the procedures set out in [RFC3209] and does not define statement of the procedures set out in [RFC3209] and does not define
any new behavior. any new behavior.
2.1. Behavior at Detecting Nodes 2.1. Behavior at Detecting Nodes
In the case of fatal errors, the detecting node must send a PathErr In the case of fatal errors ("Hard Preemption" see section 4.7.3 of
message reporting the error condition, and must clear the [RFC3209]), the detecting node SHOULD send a PathErr message
corresponding Path and Resv (control plane) states. A direct reporting the error condition, and clears the corresponding Path and
implication is that the data plane resources of such a TE LSP are Resv (control plane) states. A direct implication is that the data
also released, thus resulting in traffic disruption. It should be plane resources of such a TE LSP are also released, thus resulting in
noted, however, that in fatal error cases, the LSP has usually traffic disruption. It should be noted, however, that in fatal error
already failed in the data plane, and traffic has already been cases, the LSP has usually already failed in the data plane, and
disrupted. When the error arises during LSP establishment, the traffic has already been disrupted. When the error arises during LSP
implications are different to when it arises on an active LSP since establishment, the implications are different to when it arises on an
no traffic flows until the LSP has been fully established. In the active LSP since no traffic flows until the LSP has been fully
case of non-fatal errors, the detecting node should send a PathErr established. In the case of non-fatal errors, the detecting node
message, and must not clear control plane or data plane state. should send a PathErr message, and must not clear control plane or
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] a node This includes the head-end node. In accordance with [RFC2205]
receiving a PathErr message takes no action upon it and consequently Section 3.7.1, a node receiving a PathErr message takes no action
it must not clear Path or Resv control plane or data plane state. upon it and consequently it must not clear Path or Resv control plane
This is true regardless of whether the error condition reported by or data plane state. This is true regardless of whether the error
the PathErr is fatal or non-fatal. RSVP states should only be condition reported by the PathErr is fatal or non-fatal. RSVP states
affected upon receiving a PathTear or ResvTear message, or in the should only be affected upon receiving a PathTear or ResvTear
event of a Path or Resv state timeout. Further discussion of the message, or in the event of a Path or Resv state timeout. Further
processing of these events is outside the scope of this document. 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 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 can be used to report a preempted TE LSPs: Two Error-code 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. In both cases, these are fatal errors.
4. IANA Considerations 4. IANA Considerations
This document does not define any new protocol extensions and thus no This document does not define any new protocol extensions and thus no
action is requested to IANA. action is requested to IANA.
5. Security Considerations 5. 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. This document does not raise specific security issues specified in [RFC3209] and [RFC3473]. This document does not raise
beyond those of existing MPLS-TE. By clarifying the procedures, this specific security issues beyond those of existing MPLS-TE. By
document reduces the security risk introduced by non-conformant clarifying the procedures, this document reduces the security risk
implementations. introduced by non-conformant implementations. See
[I-D.ietf-mpls-mpls-and-gmpls-security-framework] for further
discussion of MPLS security issues.
6. Acknowledgements 6. Acknowledgements
The author would like to thank Carol Iturralde, Ashok Narayanan, Rom The author would like to thank Carol Iturralde, Ashok Narayanan, Rom
Reuther and Reshad Rahman. Reuther and Reshad Rahman.
7. Normative References 7. References
7.1. 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
[I-D.ietf-mpls-mpls-and-gmpls-security-framework]
Fang, L. and M. Behringer, "Security Framework for MPLS
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
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