draft-ietf-pce-pcep-xro-04.txt   draft-ietf-pce-pcep-xro-05.txt 
Network Working Group E. Oki Network Working Group E. Oki
Internet Draft T. Takeda Internet Draft T. Takeda
Category: Standards Track NTT Intended Status: Standards Track NTT
Expires: September 2008 A. Farrel Created: March 24th, 2008 A. Farrel
Old Dog Consulting Expires: September 24th, 2008 Old Dog Consulting
Extensions to the Path Computation Element Communication Protocol Extensions to the Path Computation Element Communication Protocol
(PCEP) for Route Exclusions (PCEP) for Route Exclusions
draft-ietf-pce-pcep-xro-04.txt draft-ietf-pce-pcep-xro-05.txt
Status of this Memo Status of this Memo
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Abstract Abstract
The Path Computation Element (PCE) provides functions of path The Path Computation Element (PCE) provides functions of path
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Conventions used in this document Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC 2119 this document are to be interpreted as described in RFC 2119
[RFC2119]. [RFC2119].
Table of Contents Table of Contents
1. Introduction...................................................2 1. Introduction ................................................. 3
2. Protocol Procedures and Extensions.............................3 2. Protocol Procedures and Extensions ........................... 3
2.1. Exclude Route Object (XRO)..................................4 2.1. Exclude Route Object (XRO) ................................. 4
2.1.1. Definition................................................4 2.1.1. Definition ............................................... 4
2.1.2. Processing Rules..........................................8 2.1.2. Processing Rules ......................................... 8
2.2. Explicit Route Exclusion....................................9 2.2. Explicit Route Exclusion ................................... 9
2.2.1. Definition..................................................9 2.2.1. Definition ............................................... 9
2.2.2. Processing Rules...........................................10 2.2.2. Processing Rules ........................................ 10
3. Exclude Route with Confidentiality............................11 3. Exclude Route with Confidentiality .......................... 11
3.1. Exclude Route Object (XRO) Carrying Path Key...............11 3.1. Exclude Route Object (XRO) Carrying Path Key .............. 11
3.1.1. Definition.................................................11 3.1.1. Definition .............................................. 11
3.1.2. Processing Rules...........................................11 3.1.2. Processing Rules ........................................ 11
4. IANA Considerations...........................................12 4. IANA Considerations ......................................... 12
4.1. PCEP Objects...............................................12 4.1. PCEP Objects .............................................. 12
4.2. Explicit Exclusion Route Subobject (EXRS)..................12 4.2. New Subobject for the Include Route Object ................ 13
4.3. Error Object Field Values..................................13 4.3. Error Object Field Values ................................. 13
5. Manageability Considerations..................................13 4.4. Exclude Route Flags ....................................... 13
6. Security Considerations.......................................13 5. Manageability Considerations ................................ 14
7. References....................................................14 6. Security Considerations ..................................... 14
7.1. Normative Reference........................................14 7. References .................................................. 14
7.2. Informative Reference......................................14 7.1. Normative Reference ....................................... 14
8. Acknowledgements..............................................15 7.2. Informative Reference ..................................... 15
9. Authors' Addresses............................................15 8. Acknowledgements ............................................ 15
10. Intellectual Property Statement.............................15 9. Authors' Addresses .......................................... 15
10. Intellectual Property Statement ............................ 16
1. Introduction 1. Introduction
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The Path Computation Element (PCE) defined in [RFC4655] is an entity The Path Computation Element (PCE) defined in [RFC4655] is an entity
that is capable of computing a network path or route based on a that is capable of computing a network path or route based on a
network graph, and applying computational constraints. A Path network graph, and applying computational constraints. A Path
Computation Client (PCC) may make requests to a PCE for paths to be Computation Client (PCC) may make requests to a PCE for paths to be
computed. computed.
When a PCC requests a PCE for a route, it may be useful for the PCC When a PCC requests a PCE for a route, it may be useful for the PCC
to specify abstract nodes, resources, and Shared Risk Link Groups to specify abstract nodes, resources, and Shared Risk Link Groups
(SRLGs) that are to be explicitly excluded from the route. (SRLGs) that are to be explicitly excluded from the route.
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2. Protocol Procedures and Extensions 2. Protocol Procedures and Extensions
This section describes the procedures adopted by a PCE handling a This section describes the procedures adopted by a PCE handling a
request for path computation with route exclusions received from a request for path computation with route exclusions received from a
PCC, and defines how those exclusions are encoded. PCC, and defines how those exclusions are encoded.
There are two types of route exclusion described in [RFC4874]. There are two types of route exclusion described in [RFC4874].
1. Exclusion of certain abstract nodes or resources from the whole 1. Exclusion of certain abstract nodes or resources from the whole
path. This set of abstract nodes is referred to as the Exclude path. This set of abstract nodes is referred to as the Exclude
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Route List. Route List.
2. Exclusion of certain abstract nodes or resources between a 2. Exclusion of certain abstract nodes or resources between a
specific pair of abstract nodes present in an explicit path. Such specific pair of abstract nodes present in an explicit path. Such
specific exclusions are referred to as an Explicit Route specific exclusions are referred to as an Explicit Route
Exclusion. Exclusion.
This document defines protocol extensions to allow a PCC to specify This document defines protocol extensions to allow a PCC to specify
both types of route exclusions to a PCE on a path computation both types of route exclusions to a PCE on a path computation
request. request.
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indicate the set of elements of the original XRO that prevented the indicate the set of elements of the original XRO that prevented the
PCE from finding a path. PCE from finding a path.
The XRO MAY also be used on a PCRep message for a successful path The XRO MAY also be used on a PCRep message for a successful path
computation when the PCE wishes to provide a set of exclusions to be computation when the PCE wishes to provide a set of exclusions to be
signaled during LSP setup using the extensions to RSVP-TE [RFC4874]. signaled during LSP setup using the extensions to RSVP-TE [RFC4874].
The XRO Object-Class is to be assigned by IANA (recommended The XRO Object-Class is to be assigned by IANA (recommended
value=17) value=17)
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The XRO Object-Type is to be assigned by IANA (recommended value=1) The XRO Object-Type is to be assigned by IANA (recommended value=1)
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |F| | Reserved | Flags |F|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// (Subobjects) // // (Subobjects) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |F| | Reserved | Flags |F|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// (Subobjects) // // (Subobjects) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: XRO body format Figure 1: XRO body format
Reserved: 16 bits EMUST be set to zero on transmission and SHOULD Reserved: 16 bits - MUST be set to zero on transmission and SHOULD
be ignored on receipt. be ignored on receipt.
Flags: 16 bits - The following flags are currently defined: Flags: 16 bits - The following flags are currently defined:
F (Fail - 1 bit): when set, the requesting PCC requires the F (Fail - 1 bit): when set, the requesting PCC requires the
computation of a new path for an existing TE LSP that has failed. computation of a new path for an existing TE LSP that has failed.
If the F bit is set, the path of the existing TE LSP MUST be If the F bit is set, the path of the existing TE LSP MUST be
provided in the PCReq message by means of an RRO object defined in provided in the PCReq message by means of an RRO object defined in
[PCEP]. This allows the path computation to take into account the [PCEP]. This allows the path computation to take into account the
previous path and reserved resources to avoid double bandwidth previous path and reserved resources to avoid double bandwidth
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Subobjects. The XRO is up made of one or more subobject(s). An XRO Subobjects. The XRO is up made of one or more subobject(s). An XRO
with no subobjects MUST NOT be sent and SHOULD be ignored on receipt. with no subobjects MUST NOT be sent and SHOULD be ignored on receipt.
In the following subobject definitions a set of fields have In the following subobject definitions a set of fields have
consistent meaning as follows: consistent meaning as follows:
X X
The X-bit indicates whether the exclusion is mandatory or The X-bit indicates whether the exclusion is mandatory or
desired. 0 indicates that the resource specified MUST be desired. 0 indicates that the resource specified MUST be
excluded from the path computed by the PCE. 1 indicates that excluded from the path computed by the PCE. 1 indicates that the
the
resource specified SHOULD be excluded from the path computed by resource specified SHOULD be excluded from the path computed by
the PCE, but MAY be included subject to PCE policy and the the PCE, but MAY be included subject to PCE policy and the
absence of a viable path that meets the other constraints and absence of a viable path that meets the other constraints and
excludes the resource. excludes the resource.
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Type Type
The type of the subobject. The following subobject types are The type of the subobject. The following subobject types are
defined. defined.
Type Subobject Type Subobject
-------------+------------------------------- -------------+-------------------------------
1 IPv4 prefix 1 IPv4 prefix
2 IPv6 prefix 2 IPv6 prefix
3 Unnumbered Interface ID 4 Unnumbered Interface ID
4 Autonomous system number 32 Autonomous system number
5 SRLG 34 SRLG
Length Length
The length of the subobject including the Type and Length The length of the subobject including the Type and Length
fields. fields.
Prefix Length Prefix Length
Where present, this field can be used to indicate a set of Where present, this field can be used to indicate a set of
addresses matching a prefix. If the subobject indicates a addresses matching a prefix. If the subobject indicates a
single address, the prefix length MUST be set to the full single address, the prefix length MUST be set to the full
length of the address. length of the address.
Attribute Attribute
The Attribute field indicates how the exclusion subobject is to The Attribute field indicates how the exclusion subobject is to
be interpreted. be interpreted.
0 Interface 0 Interface
The subobject is to be interpreted as an interface or set of The subobject is to be interpreted as an interface or set of
interfaces. All interfaces identified by the subobject are interfaces. All interfaces identified by the subobject are to
to
be excluded from the computed path according to the setting be excluded from the computed path according to the setting
of the X-bit. This value is valid only for subobject types 1, of the X-bit. This value is valid only for subobject types 1,
2, and 3. 2, and 3.
1 Node 1 Node
The subobject is to be interpreted as a node or set of nodes. The subobject is to be interpreted as a node or set of nodes.
All nodes identified by the subobject are to be excluded All nodes identified by the subobject are to be excluded from
from the computed path according to the setting of the X-bit. This
the computed path according to the setting of the X-bit.
This
value is valid only for subobject types 1, 2, 3, and 4. value is valid only for subobject types 1, 2, 3, and 4.
2 SRLG 2 SRLG
The subobject identifies an SRLG explicitly or indicates all The subobject identifies an SRLG explicitly or indicates all
of the SRLGs associated with the resource or resources of the SRLGs associated with the resource or resources
identified by the subobject. Resources that share any SRLG identified by the subobject. Resources that share any SRLG
with those identified are to be excluded from the computed with those identified are to be excluded from the computed
path according to the setting of the X-bit. This value is path according to the setting of the X-bit. This value is
valid for all subobjects. valid for all subobjects.
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Reserved Reserved
Reserved fields within subobjects MUST be transmitted as zero Reserved fields within subobjects MUST be transmitted as zero
and SHOULD be ignored on receipt. and SHOULD be ignored on receipt.
The subobjects are encoded as follows: The subobjects are encoded as follows:
IPv4 prefix Subobject IPv4 prefix Subobject
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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|X| Type = 3 | Length | Reserved | Attribute | |X| Type = 3 | Length | Reserved | Attribute |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Router ID | | TE Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID | | Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The TE Router ID and Interface ID fields are as defined in The TE Router ID and Interface ID fields are as defined in
[RFC3477]. [RFC3477].
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Autonomous System Number Subobject Autonomous System Number Subobject
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type = 4 | Length | 2-Octet AS Number | |X| Type = 4 | Length | 2-Octet AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SRLG Subobject SRLG Subobject
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If the PCE does not recognize the XRO it MUST return a PCErr message If the PCE does not recognize the XRO it MUST return a PCErr message
with Error-Type "Unknown Object" as described in [PCEP]. with Error-Type "Unknown Object" as described in [PCEP].
If the PCE is unwilling on unable to process the XRO it MUST return If the PCE is unwilling on unable to process the XRO it MUST return
a PCErr message with the Error-Type "Not supported object" and a PCErr message with the Error-Type "Not supported object" and
follow the relevant procedures described in [PCEP]. follow the relevant procedures described in [PCEP].
If the PCE processes the XRO and attempts to compute a path, it MUST If the PCE processes the XRO and attempts to compute a path, it MUST
adhere to the requested exclusions as expressed in the XRO. That is, adhere to the requested exclusions as expressed in the XRO. That is,
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the returned path MUST NOT include any resources encoded with the X- the returned path MUST NOT include any resources encoded with the X-
bit clear, and SHOULD NOT include any with the X-bit set unless bit clear, and SHOULD NOT include any with the X-bit set unless
alternate paths that match the other constraints expressed in the alternate paths that match the other constraints expressed in the
PCReq are unavailable. PCReq are unavailable.
When a PCE returns a path in a PCRep it MAY also supply an XRO. An When a PCE returns a path in a PCRep it MAY also supply an XRO. An
XRO in a PCRep message with the NO-PATH object indicates that the XRO in a PCRep message with the NO-PATH object indicates that the
set of elements of the original XRO prevented the PCE from finding a set of elements of the original XRO prevented the PCE from finding a
path. On the other hand, if an XRO is present in a PCRep message path. On the other hand, if an XRO is present in a PCRep message
without a NO-PATH object, the PCC SHOULD apply the contents using without a NO-PATH object, the PCC SHOULD apply the contents using
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2.2.1. Definition 2.2.1. Definition
Explicit Route Exclusion defines network elements that must not or Explicit Route Exclusion defines network elements that must not or
should not be used on the path between two abstract nodes or should not be used on the path between two abstract nodes or
resources explicitly indicated in the Include Route Object (IRO) resources explicitly indicated in the Include Route Object (IRO)
[PCEP]. This information is encoded by defining a new subobject for [PCEP]. This information is encoded by defining a new subobject for
the IRO. the IRO.
The new IRO subobject, the Explicit Exclusion Route Subobject (EXRS), The new IRO subobject, the Explicit Exclusion Route Subobject (EXRS),
has type defined by IANA (see Section 3.). The EXRS contains one or has type defined by IANA (see Section 4). The EXRS contains one or
more subobjects in its own right. An EXRS MUST NOT be sent with no more subobjects in its own right. An EXRS MUST NOT be sent with no
subobjects, and if received with no subobjects MUST be ignored. subobjects, and if received with no subobjects MUST be ignored.
The format of the EXRS is as follows: The format of the EXRS is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved | |L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// One or more EXRS subobjects // // One or more EXRS subobjects //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L L
MUST be set to zero on transmission and MUST be ignored on MUST be set to zero on transmission and MUST be ignored on
receipt. receipt.
Reserved Reserved
MUST be set to zero on transmission and SHOULD be ignored on MUST be set to zero on transmission and SHOULD be ignored on
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receipt. receipt.
The EXRS subobject may carry any of the subobjects defined for The EXRS subobject may carry any of the subobjects defined for
inclusion in the XRO by this document or by future documents. The inclusion in the XRO by this document or by future documents. The
meanings of the fields of the XRO subobjects are unchanged when the meanings of the fields of the XRO subobjects are unchanged when the
subobjects are included in an EXRS, except that scope of the subobjects are included in an EXRS, except that scope of the
exclusion is limited to the single hop between the previous and exclusion is limited to the single hop between the previous and
subsequent elements in the IRO. subsequent elements in the IRO.
2.2.2. Processing Rules 2.2.2. Processing Rules
A PCC that supplies a partial explicit route to a PCE in an IRO MAY A PCC that supplies a partial explicit route to a PCE in an IRO MAY
also specify explicit exclusions by including one or more EXRSes in also specify explicit exclusions by including one or more EXRSs in
the IRO. the IRO.
If a PCE parses an IRO in a received PCReq message and encounters an If a PCE parses an IRO in a received PCReq message and encounters an
EXRS and does not recognize the subobject it MUST respond with a EXRS and does not recognize the subobject it MUST respond with a
PCErr message using the Error-Type "Unrecognized IRO subobject" and PCErr message using the Error-Type "Unknown Object" or "Not supported
set the Error-Value to the subobject type code of the EXRS. object" and set the Error-Value to "Unrecognized subobject type" or
"Unsupported subobject type" as described in [PCEP]. The PCE MAY also
include the IRO in the PCErr to indicate in which case, the IRO
SHOULD be terminated immediately after the unrecognized EXRS.
If a PCE parses an IRO and encounters an EXRS that it recognizes, If a PCE that supports the EXRS in an IRO parses an IRO and
but detects an EXRS subobject that it does not recognize it MUST act encounters an EXRS that contains a subobject that it does not support
according to the setting of the X-bit in the subobject. If the X-bit or recognize it MUST act according to the setting of the X-bit in the
is clear, the PCE MUST respond with a PCErr with Error-Type subobject. If the X-bit is clear, the PCE MUST respond with a PCErr
"Unrecognized EXRS subobject" and set the Error-Value to the EXRS with Error-Type "Unrecognized EXRS subobject" and set the Error-Value
subobject type code (see Section 4). If the X-bit is set, the PCE to the EXRS subobject type code (see Section 4). If the X-bit is set,
MAY respond with a PCErr as already stated or MAY ignore the EXRS the PCE MAY respond with a PCErr as already stated or MAY ignore the
subobject: this choice is a local policy decision. EXRS subobject: this choice is a local policy decision.
If a PCE parses an IRO and encounters an EXRS subobject that it If a PCE parses an IRO and encounters an EXRS subobject that it
recognizes, it MUST act according to the requirements expressed in recognizes, it MUST act according to the requirements expressed in
the subobject. That is, if the X-bit is clear, the PCE MUST NOT the subobject. That is, if the X-bit is clear, the PCE MUST NOT
produce a path that includes any resource identified by the EXRS produce a path that includes any resource identified by the EXRS
subobject in the path between the previous abstract node in the IRO subobject in the path between the previous abstract node in the IRO
and the next abstract node in the IRO. If the X-bit is set, the PCE and the next abstract node in the IRO. If the X-bit is set, the PCE
SHOULD NOT produce a path that includes any resource identified by SHOULD NOT produce a path that includes any resource identified by
the EXRS subobject in the path between the previous abstract node in the EXRS subobject in the path between the previous abstract node in
the IRO and the next abstract node in the IRO unless it is not the IRO and the next abstract node in the IRO unless it is not
possible to construct a path that avoids that resource while still possible to construct a path that avoids that resource while still
complying with the other constraints expressed in the PCReq message. complying with the other constraints expressed in the PCReq message.
A successful path computation reported in a PCRep message MUST A successful path computation reported in a PCRep message MUST
include an ERO to specify the path that has been computed as include an ERO to specify the path that has been computed as
specified in [PCEP]. That ERO MAY contain specific route exclusions specified in [PCEP]. That ERO MAY contain specific route exclusions
using the EXRS as specified in [RFC4874]. using the EXRS as specified in [RFC4874].
If the path computation fails and a PCErr is returned with a NO-PATH If the path computation fails and a PCErr is returned with a NO-PATH
object, the PCE MAY include an IRO to report the hops that could not object, the PCE MAY include an IRO to report the hops that could not
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be complied with as described in [PCEP], and that IRO MAY include be complied with as described in [PCEP], and that IRO MAY include
EXRSes. EXRSs.
3. Exclude Route with Confidentiality 3. Exclude Route with Confidentiality
3.1. Exclude Route Object (XRO) Carrying Path Key 3.1. Exclude Route Object (XRO) Carrying Path Key
3.1.1. Definition 3.1.1. Definition
In PCE-based inter-domain diverse path computation, an XRO may be In PCE-based inter-domain diverse path computation, an XRO may be
used to find a backup (secondary) path. A sequential path used to find a backup (secondary) path. A sequential path
computation approach may be applied for this purpose, where a computation approach may be applied for this purpose, where a
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3.1.2. Processing Rules 3.1.2. Processing Rules
Consider that BRPC is applied for both working and backup path Consider that BRPC is applied for both working and backup path
computation in a sequential manner. First, PCC requests PCE for the computation in a sequential manner. First, PCC requests PCE for the
computation of a working path. After BRPC processing has completed, computation of a working path. After BRPC processing has completed,
the PCC receives the results of the working-path computation the PCC receives the results of the working-path computation
expressed in an ERO in a PCRep message. The ERO may include PKSs if expressed in an ERO in a PCRep message. The ERO may include PKSs if
certain segments of the path are to be kept confidential. certain segments of the path are to be kept confidential.
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For backup path computation, when the PCC constructs a PCReq Message, For backup path computation, when the PCC constructs a PCReq Message,
it includes the entire working-path in the XRO so that the computed it includes the entire working-path in the XRO so that the computed
path is node/link disjoint from the working path. The XRO may also path is node/link disjoint from the working path. The XRO may also
include SRLGs to ensure SRLG diversity from the working path. If the include SRLGs to ensure SRLG diversity from the working path. If the
working path ERO includes PKS subobjects, these are also included in working path ERO includes PKS subobjects, these are also included in
the XRO to allow the PCE to ensure diversity. the XRO to allow the PCE to ensure diversity.
A set of PCEs for backup path computation may be the same as ones A set of PCEs for backup path computation may be the same as ones
for working path computation, or they may be different. for working path computation, or they may be different.
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it includes the entire working-path in the XRO so that the computed it includes the entire working-path in the XRO so that the computed
path is node/link disjoint from the working path. The XRO may also path is node/link disjoint from the working path. The XRO may also
include SRLGs to ensure SRLG diversity from the working path. If the include SRLGs to ensure SRLG diversity from the working path. If the
working path ERO includes PKS subobjects, these are also included in working path ERO includes PKS subobjects, these are also included in
the XRO to allow the PCE to ensure diversity. the XRO to allow the PCE to ensure diversity.
A set of PCEs for backup path computation may be the same as ones A set of PCEs for backup path computation may be the same as ones
for working path computation, or they may be different. for working path computation, or they may be different.
- Identical PCEs - Identical PCEs
In the case where the same PCEs are used for both path In the case where the same PCEs are used for both path
computations, the processing is as follows. During the process of computations, the processing is as follows. During the process of
BRPC for backup path computation, a PCE may encounter a PKS as it BRPC for backup path computation, a PCE may encounter a PKS as it
processes the XRO when it creates a virtual path tree (VPT) in its processes the XRO when it creates a virtual path tree (VPT) in its
own domain. The PCE retrieves the PCE-ID from the PKS, recognizes own domain. The PCE retrieves the PCE-ID from the PKS, recognizes
itself, and converts the PKS into a set of XRO subobjects which it itself, and converts the PKS into a set of XRO subobjects which it
uses for the local calculation to create the VPT. The XRO subobjects uses for the local calculation to create the VPT. The XRO
created in this way MUST NOT be shared with other PCEs. Other subobjects created in this way MUST NOT be shared with other PCEs.
operations are the same as BRPC. Other operations are the same as BRPC.
- Different PCEs - Different PCEs
In the case where a set of PCEs for bakup path computation is In the case where a set of PCEs for bakup path computation is
different from the ones used for working path computation, the different from the ones used for working path computation, the
processing is as follows. If a PCE encounters a PKS in an XRO when processing is as follows. If a PCE encounters a PKS in an XRO when
it is creating a virtual path tree in its own domain, the PCE it is creating a virtual path tree in its own domain, the PCE
retrieves the PCE-ID from the PKS and sends a PCReq message to the retrieves the PCE-ID from the PKS and sends a PCReq message to the
identified PCE to expand the PKS. The PCE computing the VPT treats identified PCE to expand the PKS. The PCE computing the VPT treats
the path segment in the response as a set of XRO subobjects in the path segment in the response as a set of XRO subobjects in
performing its path computation. The XRO subobjects determined in performing its path computation. The XRO subobjects determined in
this way MUST NOT be shared with other PCEs. this way MUST NOT be shared with other PCEs.
skipping to change at line 567 skipping to change at page 12, line 38
this way MUST NOT be shared with other PCEs. this way MUST NOT be shared with other PCEs.
4. IANA Considerations 4. IANA Considerations
4.1. PCEP Objects 4.1. PCEP Objects
The "PCEP Parameters" registry contains a subregistry "PCEP Objects". The "PCEP Parameters" registry contains a subregistry "PCEP Objects".
IANA is requested to make the following allocations from this IANA is requested to make the following allocations from this
registry. registry.
Object Name Object Name Object Name Reference
Class Type Class
17 XRO 1 Route exclusion 17 XRO [This.ID]
Object-Type
1: Route exclusion
4.2. Explicit Exclusion Route Subobject (EXRS) This object should be registered as being allowed to carry the
following subobjects:
Oki, Takeda and Farrel Expires September 2008 12 Subobject Type Reference
The "PCEP Parameters" registry contains a subregistry “IRO 1 IPv4 prefix [RFC3209]
subobjectE IANA is requested to make the following allocation from 2 IPv6 prefix [RFC3209]
this registry for the Explicit Exclusion Route Subobject (EXRS). 4 Unnumbered Interface ID [RFC3477]
32 Autonomous system number [RFC3209]
34 SRLG [RFC4874]
64 IPv4 Path Key [PCE-PATH-KEY]
65 IPv6 Path Key [PCE-PATH-KEY]
Subobject Name 4.2. New Subobject for the Include Route Object
Type 33 EXRS
4.3. Error Object Field Values. The "PCEP Parameters" registry contains a subregistry "PCEP Objects"
with an entry for the Include Route Object (IRO).
The "PCEP Parameters" registry contains a subregistry "PCEP Errors". IANA is requested to indicate that a further subobject can be carried
IANA is requested to make the following allocations from this in the IRO as follows:
registry.
Values in this section are recommended and to be confirmed by IANA. Subobject Type Reference
Error Meaning and Error-Values 33 Explicit Exclusion Route subobject (EXRS) [RFC4874]
Type
11 Unrecognized IRO subobject 4.3. Error Object Field Values
Note that this Error-Type has been omitted from [PCEP] where it is
required. It is expected that it will be added to a later version of
[PCEP] and removed from this document.
12 Unrecognized EXRS subobject The "PCEP Parameters" registry contains a subregistry "Error Types
and Values". IANA is requested to make the following allocations from
this subregistry.
The value in this section is recommended and to be confirmed by IANA.
Error
Type Meaning Reference
11 Unrecognized EXRS subobject [This.I-D]
4.4. Exclude Route Flags
IANA is requested to create a subregistry of the "PCEP Parameters"
for the bits carried in the Flags field of the Exclude Route Object
(XRO). The subregistry should be called "Exclude Route Flags".
New bits may be allocated only by an IETF Consensus action.
The field contains 16 bits numbered from 1 as the least significant
bit.
Bit Name Description Reference
15 F-bit Fail [This.I-D]
5. Manageability Considerations 5. Manageability Considerations
A MIB module for management of the PCEP is specified in a separate A MIB module for management of the PCEP is specified in a separate
document. This MIB module allows examination of individual PCEP document. This MIB module allows examination of individual PCEP
messages, in particular requests, responses and errors. messages, in particular requests, responses and errors.
The MIB module MUST be extended to include the ability to view the The MIB module MUST be extended to include the ability to view the
route exclusion extensions defined in this document. route exclusion extensions defined in this document.
skipping to change at line 621 skipping to change at page 14, line 27
Second, the behavior on receipt of an unrecognized XRO or EXRS Second, the behavior on receipt of an unrecognized XRO or EXRS
subobject with the X-bit set should be configurable and must be subobject with the X-bit set should be configurable and must be
available for inspection. The inspection and control of these local available for inspection. The inspection and control of these local
policy choices may be part of the PCEP MIB module. policy choices may be part of the PCEP MIB module.
6. Security Considerations 6. Security Considerations
The new exclude route mechanisms defined in this document allow The new exclude route mechanisms defined in this document allow
finer and more specific control of the path computed by a PCE. Such finer and more specific control of the path computed by a PCE. Such
control increases the risk if a PCEP message is intercepted, control increases the risk if a PCEP message is intercepted,
Oki, Takeda and Farrel Expires September 2008 13
modified, or spoofed. Therefore, the security techniques described modified, or spoofed. Therefore, the security techniques described
in [PCEP] are considered more important. in [PCEP] are considered more important.
Note, however, that the roue exclusion mechanisms also provide the Note, however, that the roue exclusion mechanisms also provide the
operator with the ability to route around vulnerable parts of the operator with the ability to route around vulnerable parts of the
network and may be used to increase overall network security. network and may be used to increase overall network security.
7. References 7. References
7.1. Normative Reference 7.1. Normative Reference
[RFC2119] Bradner, S., "Key words for use in RFCs to indicate [RFC2119] Bradner, S., "Key words for use in RFCs to indicate
requirements levels", RFC 2119, March 1997. requirements levels", RFC 2119, March 1997.
[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.
[PCEP] JP. Vasseur et al, "Path Computation Element (PCE) [PCEP] JP. Vasseur et al, "Path Computation Element (PCE)
communication Protocol (PCEP) - Version 1 -" draft-ietf-pce-pcep communication Protocol (PCEP) - Version 1 -",
(work in progress). draft-ietf-pce-pcep (work in progress).
[PCE-PATH-KEY] R. Bradford, JP Vasseur, and A. Farrel, “Preserving [PCE-PATH-KEY] R. Bradford, JP Vasseur, and A. Farrel, "Preserving
Topology Confidentiality in Inter-Domain Path Computation using a Topology Confidentiality in Inter-Domain Path Computation
key based mechanismE draft-ietf-pce-path-key (work in progress). using a key based mechanism", draft-ietf-pce-path-key
(work in progress).
[BRPC] JP. Vasseur et al, "A Backward Recursive PCE-based [BRPC] JP. Vasseur et al, "A Backward Recursive PCE-based
Computation (BRPC) procedure to compute shortest inter-domain Computation (BRPC) procedure to compute shortest
Traffic Engineering Label Switched Paths", draft-ietf-pce-brpc (work inter-domain Traffic Engineering Label Switched Paths",
in progress). draft-ietf-pce-brpc (work in progress).
[RFC5152] JP. Vasseur et al, " A Per-domain path computation method [RFC5152] JP. Vasseur et al, " A Per-domain path computation method
for establishing Inter-domain Traffic Engineering (TE) Label for establishing Inter-domain Traffic Engineering (TE)
Switched Paths (LSPs)", RFC 5152.February 2008. Label Switched Paths (LSPs)", RFC 5152, February 2008.
7.2. Informative Reference 7.2. Informative Reference
[RFC3477] K. Kompella and Y. Rekhter, "Signalling Unnumbered Links [RFC3477] K. Kompella and Y. Rekhter, "Signalling Unnumbered Links
in Resource ReSerVation Protocol - Traffic Engineering (RSVP-TE)", in Resource ReSerVation Protocol - Traffic Engineering
RFC 3477, January 2003. (RSVP-TE)", RFC 3477, January 2003.
[RFC3812] Srinivasan, C., Viswanathan, A., and T. Nadeau, [RFC3812] Srinivasan, C., Viswanathan, A., and T. Nadeau,
"Multiprotocol Label Switching (MPLS) Traffic Engineering (TE) "Multiprotocol Label Switching (MPLS) Traffic Engineering
Management Information Base (MIB)", RFC 3812, June 2004. (TE) Management Information Base (MIB)", RFC 3812, June
2004.
[RFC4655] A. Farrel, JP. Vasseur and J. Ash, "A Path Computation [RFC4655] A. Farrel, JP. Vasseur and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, September 2006. Element (PCE)-Based Architecture", RFC 4655, September
2006.
[RFC4657] J. Ash and J.L. Le Roux, "Path Computation Element (PCE) [RFC4657] J. Ash and J.L. Le Roux, "Path Computation Element (PCE)
Communication Protocol Generic Requirements", RFC 4657, September Communication Protocol Generic Requirements", RFC 4657,
2006. September 2006.
Oki, Takeda and Farrel Expires September 2008 14
[RFC4874] Lee et al, "Exclude Routes - Extension to Resource [RFC4874] Lee et al, "Exclude Routes - Extension to Resource
ReserVation Protocol-Traffic Engineering (RSVP-TE)", RFC 4874, April ReserVation Protocol-Traffic Engineering (RSVP-TE)",
2007. RFC 4874, April 2007.
[INTER-DOMAIN-REC-ANA] T. Takeda et al., "Analysis of Inter-domain [INTER-DOMAIN-REC-ANA] T. Takeda et al., "Analysis of Inter-domain
Label Switched Path (LSP) Recovery" draft-ietf-ccamp-inter-domain- Label Switched Path (LSP) Recovery",
recovery-analysis (work in progress). draft-ietf-ccamp-inter-domain-recovery-analysis (work in
progress).
8. Acknowledgements 8. Acknowledgements
Authors would like to thank Fabien Verhaeghe for valuable comments Authors would like to thank Fabien Verhaeghe for valuable comments
on subobject formats. on subobject formats.
9. Authors' Addresses 9. Authors' Addresses
Eiji Oki Eiji Oki
NTT NTT
skipping to change at line 721 skipping to change at page 16, line 32
Information on the procedures with respect to rights in RFC Information on the procedures with respect to rights in RFC
documents can be found in BCP 78 and BCP 79. documents can be found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use attempt made to obtain a general license or permission for the use
of such proprietary rights by implementers or users of this of such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository specification can be obtained from the IETF on-line IPR repository
at http://www.ietf.org/ipr. at http://www.ietf.org/ipr.
Oki, Takeda and Farrel Expires September 2008 15
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf- this standard. Please address the information to the IETF at ietf-
ipr@ietf.org. ipr@ietf.org.
Disclaimer of Validity Disclaimer of Validity
This document and the information contained herein are provided on This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
skipping to change at line 746 skipping to change at line 760
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE. FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
Oki, Takeda and Farrel Expires September 2008 16
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