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

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   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.

Copyright Notice

   Copyright (c) 2009 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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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.

6.

5.  Acknowledgements

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

7.

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