draft-ietf-pce-pcecp-interarea-reqs-05.txt   rfc4927.txt 
Network Working Group J.-L. Le Roux (Editor) Network Working Group J.-L. Le Roux, Ed.
Internet Draft France Telecom Request for Comments: 4927 France Telecom
Path Computation Element Communication Protocol (PCECP) Specific
Category: Informational Requirements for Inter-Area MPLS and GMPLS Traffic Engineering
December 2006
PCE Communication Protocol (PCECP) Specific Requirements for Inter-Area
Multi Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS)
Traffic Engineering
draft-ietf-pce-pcecp-interarea-reqs-05.txt
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Abstract Abstract
For scalability purposes a network may comprise multiple Interior For scalability purposes, a network may comprise multiple Interior
Gateway Protocol (IGP) areas. An inter-area Traffic Engineered-Label Gateway Protocol (IGP) areas. An inter-area Traffic Engineered Label
Switched Path (TE-LSP) is an LSP that transits through at least two Switched Path (TE-LSP) is an LSP that transits through at least two
IGP areas. In a multi-area network, topology visibility remains local IGP areas. In a multi-area network, topology visibility remains
to a given area, and a head-end Label Switching Router (LSR) cannot local to a given area, and a head-end Label Switching Router (LSR)
compute an inter-area shortest constrained path. One key application cannot compute an inter-area shortest constrained path. One key
of the Path Computation Element (PCE) based architecture is the application of the Path Computation Element (PCE)-based architecture
computation of inter-area TE-LSP paths. The PCE Communication is the computation of inter-area TE-LSP paths. The PCE Communication
Protocol (PCECP) is used to communicate computation requests from Protocol (PCECP) is used to communicate computation requests from
Path Computation Clients (PCC) to PCEs, and to return computed paths Path Computation Clients (PCCs) to PCEs, and to return computed paths
in responses. This document lists a detailed set of PCECP specific in responses. This document lists a detailed set of PCECP-specific
requirements for support of inter-area TE-LSP path computation. It requirements for support of inter-area TE-LSP path computation. It
complements the generic requirements for a PCE Communication complements the generic requirements for a PCE Communication
Protocol. Protocol.
Conventions used in this document
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.
Table of Contents Table of Contents
1. Terminology.................................................3 1. Introduction ....................................................2
2. Introduction................................................3 2. Terminology .....................................................3
3. Motivations for PCE-based Inter-Area Path Computation.......4 2.1. Conventions Used in This Document ..........................4
4. Detailed Inter-Area Specific Requirements on PCECP..........5 3. Motivations for PCE-Based Inter-Area Path Computation ...........4
4.1. Control and Recording of Area Crossing......................5 4. Detailed Inter-Area Specific Requirements on PCECP ..............5
4.2. Area Recording..............................................5 4.1. Control and Recording of Area Crossing .....................5
4.3. Strict Explicit Path and Loose Path.........................6 4.2. Area Recording .............................................6
4.4. PCE-list Enforcement and Recording in Multiple PCE 4.3. Strict Explicit Path and Loose Path ........................6
Computation...............................................6 4.4. PCE List Enforcement and Recording in Multiple-PCE
4.5. Inclusion of Area IDs in Request............................6 Computation ................................................6
4.6. Area Inclusion/Exclusion....................................7 4.5. Inclusion of Area IDs in Request ...........................7
4.7. Inter-area Diverse Path computation.........................7 4.6. Area Inclusion/Exclusion ...................................7
4.8. Inter-area Policies.........................................8 4.7. Inter-Area Diverse Path Computation ........................7
4.9. Loop Avoidance..............................................8 4.8. Inter-Area Policies ........................................8
5. Manageability Considerations................................8 4.9. Loop Avoidance .............................................8
6. Security Considerations.....................................8 5. Manageability Considerations ....................................9
7. Acknowledgments.............................................9 6. Security Considerations .........................................9
8. IANA Considerations.........................................9 7. Acknowledgments .................................................9
9. References..................................................9 8. References ......................................................9
9.1. Normative References........................................9 8.1. Normative References .......................................9
9.2. Informative References......................................9 8.2. Informative References ....................................10
10. Editor Address:.............................................9 9. Contributors ...................................................10
11. Contributors' Addresses....................................10
12. Intellectual Property Statement............................11
1. Terminology
LSR: Label Switching Router.
LSP: MPLS Label Switched Path.
TE-LSP: Traffic Engineering Label Switched Path.
IGP area: OSPF Area or IS-IS level.
ABR: IGP Area Border Router, a router that is attached to more
than one IGP areas (ABR in OSPF or L1/L2 router in IS-IS).
Inter-Area TE LSP: TE LSP that traverses more than one IGP area.
CSPF: Constrained Shortest Path First.
SRLG: Shared Risk Link Group.
PCE: Path Computation Element: an entity (component, application
or network node) that is capable of computing a network path or
route based on a network graph and applying computational
constraints.
PCC: Path Computation Client, any application that request path
computation to be performed by a PCE.
PCECP: PCE Communication Protocol, a protocol for communication
between PCCs and PCEs, and between PCEs.
ERO: RSVP-TE Explicit Route Object. It encodes the explicit path
followed by a TE-LSP.
2. Introduction 1. Introduction
[RFC4105] lists a set of motivations and requirements for setting up [RFC4105] lists a set of motivations and requirements for setting up
TE-LSPs across IGP area boundaries. These LSPs are called inter-area TE-LSPs across IGP area boundaries. These LSPs are called inter-area
TE-LSPs. These requirements include the computation of inter- TE-LSPs. These requirements include the computation of inter-area
area shortest constrained paths with key guideline being to respect shortest constrained paths with a key guideline being to respect the
the IGP hierarchy concept, and particularly the containment of IGP hierarchy concept, and particularly the containment of topology
topology information. The main challenge with inter-area MPLS-TE lies information. The main challenge with inter-area MPLS-TE lies in path
in path computation. Indeed the head-end LSR cannot compute an computation. Indeed, the head-end LSR cannot compute an explicit
explicit path across areas, as its topology visibility is limited to path across areas, as its topology visibility is limited to its own
its own area. area.
Inter-area path computation is one of the key applications of the PCE Inter-area path computation is one of the key applications of the
based architecture [RFC4655]. The computation of optimal inter-area PCE-based architecture [RFC4655]. The computation of optimal inter-
paths may be achieved using the services of one or more PCEs. area paths may be achieved using the services of one or more PCEs.
Such PCE-based inter-area path computation could rely for instance on Such PCE-based inter-area path computation could rely for instance on
a single multi-area PCE that has the TE database of all the areas in a single multi-area PCE that has the TE database of all the areas in
the IGP domain and can directly compute an end-to-end constrained the IGP domain and can directly compute an end-to-end constrained
shortest path. Alternatively, this could rely on the cooperation shortest path. Alternatively, this could rely on the cooperation
between PCEs whereby each PCE covers one or more IGP areas and the between PCEs whereby each PCE covers one or more IGP areas and the
full set of PCEs covers all areas. full set of PCEs covers all areas.
The generic requirements for a PCE Communication Protocol (PCECP), The generic requirements for a PCE Communication Protocol (PCECP),
which allows a PCC to send path computation requests to a PCE and the which allows a PCC to send path computation requests to a PCE and the
skipping to change at page 4, line 30 skipping to change at page 3, line 23
path computation. path computation.
It is expected that PCECP procedures be defined to satisfy these It is expected that PCECP procedures be defined to satisfy these
requirements. requirements.
Note that PCE-based inter-area path computation may require a Note that PCE-based inter-area path computation may require a
mechanism for automatic PCE discovery across areas, which is out of mechanism for automatic PCE discovery across areas, which is out of
the scope of this document. Detailed requirements for such a the scope of this document. Detailed requirements for such a
mechanism are discussed in [RFC4674]. mechanism are discussed in [RFC4674].
3. Motivations for PCE-based Inter-Area Path Computation 2. Terminology
IGP hierarchy enables improved IGP scalability, by dividing the IGP LSR: Label Switching Router.
LSP: MPLS Label Switched Path.
TE-LSP: Traffic Engineered Label Switched Path.
IGP area: OSPF area or IS-IS level.
ABR: IGP Area Border Router, a router that is attached to more than
one IGP area (ABR in OSPF or L1/L2 router in IS-IS).
Inter-Area TE-LSP: TE-LSP that traverses more than one IGP area.
CSPF: Constrained Shortest Path First.
SRLG: Shared Risk Link Group.
PCE: Path Computation Element: an entity (component, application or
network node) that is capable of computing a network path or route
based on a network graph and applying computational constraints.
PCC: Path Computation Client, any application that request path
computation to be performed by a PCE.
PCECP: PCE Communication Protocol, a protocol for communication
between PCCs and PCEs, and between PCEs.
ERO: Resource Reservation Protocol (RSVP)-TE Explicit Route Object.
It encodes the explicit path followed by a TE-LSP.
2.1. Conventions Used in This Document
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 [RFC2119].
3. Motivations for PCE-Based Inter-Area Path Computation
IGP hierarchy enables improved IGP scalability by dividing the IGP
domain into areas and limiting the flooding scope of topology domain into areas and limiting the flooding scope of topology
information to within area boundaries. A router in an area has full information to within area boundaries. A router in an area has full
topology information for its own area but only information about topology information for its own area, but only information about
reachability to destinations in other areas._ Thus, a head-end LSR reachability to destinations in other areas. Thus, a head-end LSR
cannot compute an end-to-end path that crosses the boundary of its cannot compute an end-to-end path that crosses the boundary of its
IGP area(s). IGP area(s).
A current solution for computing inter-area TE-LSP path relies on a A current solution for computing inter-area TE-LSP path relies on a
per domain path computation ([PD-COMP]). It is based on loose hop per-domain path computation [PD-COMP]. It is based on loose hop
routing with an ERO expansion on each ABR. This allows an LSP to be routing with an ERO expansion on each ABR. This allows an LSP to be
set up following a constrained path, but faces two major limitations: set up following a constrained path, but faces two major limitations:
- This does guarantee the use of an optimal constrained path;
- This does guarantee the use of an optimal constrained path.
- This may lead to several crankback signaling messages and hence - This may lead to several crankback signaling messages and hence
delay the LSP setup, and may also invoke possible alternate routing delay the LSP setup, and may also invoke possible alternate routing
activities. activities.
Note that, here, by optimal constrained path we mean the shortest Note that, here, by optimal constrained path we mean the shortest
constrained path across multiple areas, taking into account either constrained path across multiple areas, taking into account either
the IGP or TE metric [METRIC]. In other words, such a path is the the IGP or TE metric [RFC3785]. In other words, such a path is the
path that would have been computed by making use of some CSPF path that would have been computed by making use of some CSPF
algorithm in the absence of multiple IGP areas. algorithm in the absence of multiple IGP areas.
The PCE based architecture [RFC4655] is well suited to inter-area The PCE-based architecture [RFC4655] is well suited to inter-area
path computation, as it allows the path computation limitations path computation. It allows the path computation limitations
resulting from the limited topology visibility to be overcome by resulting from the limited topology visibility to be overcome by
introducing path computation entities with more topology visibility, introducing path computation entities with more topology visibility,
or by allowing cooperation between path computation entities in each or by allowing cooperation between path computation entities in each
area. area.
There are two main approaches for the computation of an inter-area There are two main approaches for the computation of an inter-area
optimal path: optimal path:
- Single PCE computation: The path is computed by a single PCE that
has topology visibility in all areas and can compute an end- - Single-PCE computation: The path is computed by a single PCE that
to-end optimal constrained path on its own. has topology visibility in all areas and can compute an end-to-end
- Multiple PCE computation with inter-PCE communication: The path optimal constrained path on its own.
- Multiple-PCE computation with inter-PCE communication: The path
computation is distributed on multiple PCEs, which have partial computation is distributed on multiple PCEs, which have partial
topology visibility. They compute path segments in their domains of topology visibility. They compute path segments in their domains
visibility and collaborate with each other so as to arrive at an of visibility and collaborate with each other so as to arrive at an
end-to-end optimal constrained path. Such collaboration is ensured end-to-end optimal constrained path. Such collaboration is ensured
thanks to inter-PCE communication. thanks to inter-PCE communication.
Note that the use of a PCE-based approach, to perform inter-area path Note that the use of a PCE-based approach to perform inter-area path
computation implies specific functional requirements in a PCECP, in computation implies specific functional requirements in a PCECP, in
addition to the generic requirements listed in [RFC4657]. These addition to the generic requirements listed in [RFC4657]. These
specific requirements are discussed in next section. specific requirements are discussed in the next section.
4. Detailed Inter-Area Specific Requirements on PCECP 4. Detailed Inter-Area Specific Requirements on PCECP
This section lists a set of additional requirements for the PCECP This section lists a set of additional requirements for the PCECP
that complement requirements listed in [RFC4657] and are specific to that complement requirements listed in [RFC4657] and are specific to
inter-area (G)MPLS TE path computation. inter-area (G)MPLS-TE path computation.
4.1. Control and Recording of Area Crossing 4.1. Control and Recording of Area Crossing
In addition to the path constraints specified in [RFC4657], the In addition to the path constraints specified in [RFC4657], the
request message MUST allow indicating whether area crossing is request message MUST allow indicating whether or not area crossing is
allowed or not. Indeed, when the source and destination reside in the permitted. Indeed, when the source and destination reside in the
same IGP area, there may be intra-area and inter-area feasible paths. same IGP area, there may be intra-area and inter-area feasible paths.
As set forth in [RFC4105], if the shortest path is an inter-area As set forth in [RFC4105], if the shortest path is an inter-area
path, an operator either may want to avoid, as far as possible, path, an operator either may want to avoid, as far as possible,
crossing areas and thus may prefer selecting a sub-optimal intra-area crossing areas and thus may prefer selecting a sub-optimal intra-area
path or, conversely, may prefer to use a shortest path, even if it path or, conversely, may prefer to use a shortest path, even if it
crosses areas. crosses areas.
Also, when the source and destination reside in the same area it may Also, when the source and destination reside in the same area it may
be useful to know whether the returned path is an inter-area path. be useful to know whether the returned path is an inter-area path.
Hence the response message MUST allow indicating whether the computed Hence, the response message MUST allow indicating whether the
path is crossing areas. computed path is crossing areas.
4.2. Area Recording 4.2. Area Recording
It may be useful for the PCC to know the set of areas crossed by an It may be useful for the PCC to know the set of areas crossed by an
inter-area path and the corresponding path segments. Hence the inter-area path and the corresponding path segments. Hence, the
response message MUST allow identifying the crossed areas. Also the response message MUST allow identifying the crossed areas. Also, the
response message MUST allow segmenting the returned path and marking response message MUST allow segmenting the returned path and marking
each segment so that it is possible to tell which piece of the path each segment so that it is possible to tell which piece of the path
lie within which area. lies within which area.
4.3. Strict Explicit Path and Loose Path 4.3. Strict Explicit Path and Loose Path
A Strict Explicit Path is defined as a set of strict hops, while a A Strict Explicit Path is defined as a set of strict hops, while a
Loose Path is defined as a set of at least one loose hop and zero, Loose Path is defined as a set of at least one loose hop and zero,
one or more strict hops. An inter-area path may be strictly explicit one or more strict hops. An inter-area path may be strictly explicit
or loose (e.g. a list of ABRs as loose hops). It may be useful to or loose (e.g., a list of ABRs as loose hops). It may be useful to
indicate to the PCE if a Strict Explicit path is required or not. indicate to the PCE if a Strict Explicit path is required or not.
Hence the PCECP request message MUST allow indicating whether a Hence, the PCECP request message MUST allow indicating whether a
Strict Explicit Path is required/desired. Strict Explicit Path is required/desired.
4.4. PCE-list Enforcement and Recording in Multiple PCE Computation 4.4. PCE List Enforcement and Recording in Multiple-PCE Computation
In case of multiple-PCE inter-area path computation, a PCC may want In case of multiple-PCE inter-area path computation, a PCC may want
to indicate a preferred list of PCEs to be used, one per area. to indicate a preferred list of PCEs to be used, one per area. In
In each area the preferred PCE should be tried before another PCE be each area, the preferred PCE should be tried before another PCE is
selected. Note that if there is no preferred PCE indicated for an selected. Note that if there is no preferred PCE indicated for an
area, any PCE in that area may be used. area, any PCE in that area may be used.
Hence the PCECP request message MUST support the inclusion of a list Hence, the PCECP request message MUST support the inclusion of a list
of preferred PCEs per area. Note that this requires that a PCC in one of preferred PCEs per area. Note that this requires that a PCC in
area have knowledge of PCEs in other areas. This could rely on one area has knowledge of PCEs in other areas. This could rely on
configuration or on a PCE discovery mechanism, allowing discovery configuration or on a PCE discovery mechanism, allowing discovery
across area boundaries (see [RFC4674]). across area boundaries (see [RFC4674]).
Also it would be useful to know the list of PCEs which effectively Also, it would be useful to know the list of PCEs that effectively
participated in the computation. Hence the request message MUST participated in the computation. Hence, the request message MUST
support a request for PCE recording and the response message MUST support a request for PCE recording, and the response message MUST
support the recording of the set of one or more PCEs that took part support the recording of the set of one or more PCEs that took part
in the computation. in the computation.
It may also be useful to know the path segments computed by each PCE. It may also be useful to know the path segments computed by each PCE.
Hence the request message SHOULD allow a request for the Hence, the request message SHOULD allow a request for the
identification of path segments computed by a PCE, and the response identification of path segments computed by a PCE, and the response
message SHOULD allow identifying the path segments computed by each message SHOULD allow identifying the path segments computed by each
PCE. PCE.
4.5. Inclusion of Area IDs in Request 4.5. Inclusion of Area IDs in Request
The knowledge of the areas in which the source and destination lie Knowledge of the areas in which the source and destination lie would
would allow a PCE to select an appropriate downstream PCE. This would allow a PCE to select an appropriate downstream PCE. This would be
be useful when the area ID(s) of a PCE (i.e. the area(s) where it has useful when the area ID(s) of a PCE (i.e., the area(s) where it has
visibility) is/are known, which can be achieved by the PCE Discovery visibility) is/are known, which can be achieved by the PCE Discovery
Protocol (see [RFC4674]) or any other mean. Protocol (see [RFC4674]) or by any other means.
A PCE may not have any visibility of the source/destination area and A PCE may not have any visibility of the source/destination area and
hence may not be able to determine the area of the hence may not be able to determine the area of the
source/destination. In such a situation it would be useful that a PCC source/destination. In such a situation, it would be useful for a
indicates the source and destination area IDs in its request message. PCC to indicate the source and destination area IDs in its request
message.
For that purpose the request message MUST support the inclusion of For that purpose, the request message MUST support the inclusion of
the source and destination area IDs. Note that this information could the source and destination area IDs. Note that this information
be learned by the PCC through configuration. could be learned by the PCC through configuration.
4.6. Area Inclusion/Exclusion 4.6. Area Inclusion/Exclusion
In some situations, it may be useful that the request message In some situations, it may be useful for the request message to
indicate one or more area(s) that must be followed by the path to be indicate one or more area(s) that must be followed by the path to be
computed. It may also be useful that the request message indicate one computed. It may also be useful for the request message to indicate
or more area(s) that must be avoided by the path to be computed (e.g. one or more area(s) that must be avoided by the path to be computed
request for a path between LSRs in two stub areas connected to the (e.g., request for a path between LSRs in two stub areas connected to
same ABR(s), which must not cross the backbone area). Hence the the same ABR(s), which must not cross the backbone area). Hence, the
request message MUST allow indicating a set of one or more area(s) request message MUST allow indicating a set of one or more area(s)
that must be explicitly included in the path, and a set of one or that must be explicitly included in the path, and a set of one or
more area(s) that must be explicitly excluded from the path. more area(s) that must be explicitly excluded from the path.
4.7. Inter-area Diverse Path computation 4.7. Inter-Area Diverse Path Computation
For various reasons, including protection and load balancing, the For various reasons, including protection and load balancing, the
computation of diverse inter-area paths may be required. computation of diverse inter-area paths may be required. There are
There are various levels of diversity in an inter-area context: various levels of diversity in an inter-area context:
-Per-area diversity (intra-area path segments are link, node or
- Per-area diversity (intra-area path segments are link, node, or
SRLG disjoint) SRLG disjoint)
-Inter-area diversity (end-to-end inter-area paths are link, -Inter-area diversity (end-to-end inter-area paths are link,
node or SRLG disjoint) node, or SRLG disjoint)
Note that two paths may be disjoint in the backbone area but non- Note that two paths may be disjoint in the backbone area but non-
disjoint in peripheral areas. Also two paths may be node disjoint disjoint in peripheral areas. Also two paths may be node-disjoint
within areas but may share ABRs, in which case path segments within within areas but may share ABRs, in which case path segments within
an area are node disjoint but end-to-end paths are not node-disjoint. an area are node-disjoint, but end-to-end paths are not node
disjoint.
The request message MUST allow requesting the computation of a set of The request message MUST allow requesting the computation of a set of
inter-area diverse paths between the same node pair or between inter-area diverse paths between the same node pair or between
distinct node pairs. It MUST allow indicating the required level of distinct node pairs. It MUST allow indicating the required level of
diversity of a set of inter-area paths (link, node, SRLG diversity), diversity of a set of inter-area paths (link, node, and SRLG
as well as the required level of diversity of a set of intra-area diversity), as well as the required level of diversity of a set of
segments of inter-area paths (link, node, SRLG diversity) on a per- intra-area segments of inter-area paths (link, node, and SRLG
area basis. diversity) on a per-area basis.
The response message MUST allow indicating the level of diversity of The response message MUST allow indicating the level of diversity of
a set of computed inter-area loose paths (link, node, SRLG a set of computed inter-area loose paths (link, node, and SRLG
diversity), globally, and on a per-area basis (link, node, SRLG diversity), globally, and on a per-area basis (link, node, and SRLG
diversity of intra-area path segments). diversity of intra-area path segments).
Note that, in order to ensure SRLG consistency, SRLG identifiers Note that, in order to ensure SRLG consistency, SRLG identifiers
within the IGP domain should be assigned and allocated by the same within the IGP domain should be assigned and allocated by the same
entity. entity.
Note that specific objective functions may be requested for diverse Note that specific objective functions may be requested for diverse
path computation, such as minimizing the cumulated cost of a set of path computation, such as minimizing the cumulated cost of a set of
diverse paths as set forth in [RFC4657]. diverse paths as set forth in [RFC4657].
4.8. Inter-area Policies 4.8. Inter-Area Policies
In addition to the policy requirements discussed in [RFC4657], the In addition to the policy requirements discussed in [RFC4657], the
application of inter-area path computation policies requires some application of inter-area path computation policies requires some
additional information to be carried in the PCECP request messages. additional information to be carried in the PCECP request messages.
The request message MUST allow for the inclusion of the address of The request message MUST allow for the inclusion of the address of
the originating PCC. This may be useful in a multiple PCE the originating PCC. This may be useful in a multiple-PCE
computation, so as to apply policies not only based on the PCECP peer computation, so as to apply policies not only based on the PCECP peer
but also based on the originating PCC. but also based on the originating PCC.
Note that work on supported policy models and the corresponding Note that work on supported policy models and the corresponding
requirements/implications is being undertaken as a separate work item requirements/implications is being undertaken as a separate work item
in the PCE working group ([PCE-POL-FMWK]). in the PCE working group [PCE-POL-FMWK].
4.9. Loop Avoidance 4.9. Loop Avoidance
In case of multiple-PCE inter-area path computation, there may be In case of multiple-PCE inter-area path computation, there may be
risks of PCECP request loops. A mechanism MUST be defined to detect risks of PCECP request loops. A mechanism MUST be defined to detect
and correct PCECP request message loops. This may rely, for instance, and correct PCECP request message loops. This may rely, for
on the recording, in the request message, of the set of traversed instance, on the recording, in the request message, of the set of
PCEs. traversed PCEs.
Also the returned path in a response message MUST be loop free. Also, the returned path in a response message MUST be loop free.
5. Manageability Considerations 5. Manageability Considerations
The inter-area application implies some new manageability The inter-area application implies some new manageability
requirements in addition to those already listed in [RFC4657]. The requirements in addition to those already listed in [RFC4657]. The
PCECP PCC and PCE MIB modules MUST allow recording the proportion of PCECP PCC and PCE MIB modules MUST allow recording the proportion of
inter-area requests and the success rate of inter-area requests. The inter-area requests and the success rate of inter-area requests. The
PCEP PCC MIB module MUST also allow recording the performances of a PCECP PCC MIB module MUST also allow recording the performances of a
PCE chain (minimum, maximum and average response time), in case of PCE chain (minimum, maximum, and average response times), in case of
multiple-PCE inter-area path computation. multiple-PCE inter-area path computation.
A built in diagnostic tool MUST be defined to monitor the It is really important, for diagnostic and troubleshooting reasons,
performances of a PCE chain, in case of multiple-PCE inter-area path to monitor the availability and performances of each PCE of a PCE
computation. It MUST allow determining the minimum maximum and chain used for inter-area path computation. Particularly, it is
average response time globally for the chain, and on a per PCE basis. really important to identify the PCE(s) responsible for a delayed
reply.
Hence, a mechanism MUST be defined to monitor the performances of a
PCE chain. It MUST allow determining the availability of each PCE of
the chain as well as its minimum, maximum, and average response
times.
6. Security Considerations 6. Security Considerations
IGP areas are administrated by the same entity. Hence the inter-area IGP areas are administrated by the same entity. Hence, the inter-
application does not imply a new trust model, or new security issues area application does not imply a new trust model or new security
beyond those already defined in [RFC4657]. issues beyond those already defined in [RFC4657].
7. Acknowledgments 7. Acknowledgments
We would also like to thank Adrian Farrel, Jean-Philippe Vasseur, We would also like to thank Adrian Farrel, Jean-Philippe Vasseur,
Bruno Decraene, Yannick Le Louedec, Dimitri Papadimitriou and Lou Bruno Decraene, Yannick Le Louedec, Dimitri Papadimitriou, and Lou
Berger for their useful comments and suggestions. Berger for their useful comments and suggestions. Thanks also to
Ross Callon, Catherine Meadow, and Dan Romascanu for their review
8. IANA Considerations during the final stages of publication.
This document makes no requests for IANA action.
9. References 8. References
9.1. Normative References 8.1. 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.
[RFC4105] Le Roux J.L., Vasseur J.P., Boyle, J., et al. "Requirements [RFC4105] Le Roux, J.-L., Ed., Vasseur, J.-P., Ed., and J.
for inter-area MPLS-TE" RFC 4105, June 2005. Boyle, Ed., "Requirements for Inter-Area MPLS Traffic
Engineering", RFC 4105, June 2005.
[RFC4655] A. Farrel, JP. Vasseur and J. Ash, "Path Computation [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Element (PCE) Based Architecture", RFC4655, August 2006. Computation Element (PCE)-Based Architecture", RFC
4655, August 2006.
[RFC4657] J. Ash, J.L Le Roux et. al., "PCE Communication Protocol [RFC4657] Ash, J., Ed., and J. Le Roux, Ed., "Path Computation
Generic Requirements", RFC4657, September 2006. Element (PCE) Communication Protocol Generic
Requirements", RFC 4657, September 2006.
9.2. Informative References 8.2. Informative References
[RFC4674] J.L. Le Roux et. al., "Requirements for Path Computation [RFC4674] Le Roux, J., Ed., "Requirements for Path Computation
Element (PCE) Discovery", RFC4674, October 2006. Element (PCE) Discovery", RFC4674, October 2006.
[PD-COMP] Vasseur, J.P., Ayyangar, A., Zhang, R., "A Per-domain path [PD-COMP] Vasseur, J.P., Ed., Ayyangar, A., Ed., and R. Zhang,
computation method for computing Inter-domain Traffic Engineering "A Per-domain path computation method for computing
(TE) Label Switched Path (LSP)", work in progress. Inter-domain Traffic Engineering (TE) Label Switched
Path (LSP)", Work in Progress, April 2007.
[PCE-POL-FMWK] I. Bryskin, D. Papadimitriou, L. Berger "Policy-
Enabled Path Computation Framework", draft-ietf-pce-policy-enabled-
path-comp, work in progress.
[METRIC] Le Faucheur et al., "Use of Interior Gateway Protocol (IGP)
Metric as a second MPLS Traffic Engineering (TE) Metric", RFC3785,
May 2004.
10. Editor Address: [PCE-POL-FMWK] Bryskin, I., Papadimitriou, D., Berger L., and J.
Ash, "Policy-Enabled Path Computation Framework", Work
in Progress, March 2007.
Jean-Louis Le Roux [RFC3785] Le Faucheur, F., Uppili, R., Vedrenne, A., Merckx, P.,
France Telecom and T. Telkamp, "Use of Interior Gateway Protocol
2, avenue Pierre-Marzin (IGP) Metric as a second MPLS Traffic Engineering (TE)
22307 Lannion Cedex Metric", BCP 87, RFC 3785, May 2004.
FRANCE
Email: jeanlouis.leroux@orange-ftgroup.com
11. Contributors' Addresses 9. Contributors
Jerry Ash Jerry Ash
AT&T AT&T
Room MT D5-2A01 Room MT D5-2A01
200 Laurel Avenue 200 Laurel Avenue
Middletown, NJ 07748, USA Middletown, NJ 07748, USA
Phone: +1-(732)-420-4578 Phone: +1-(732)-420-4578
Email: gash@att.com EMail: gash5107@yahoo.com
Nabil Bitar Nabil Bitar
Verizon Verizon
40 Sylvan Road 40 Sylvan Road
Waltham, MA 02145 Waltham, MA 02145
Email: nabil.bitar@verizon.com EMail: nabil.n.bitar@verizon.com
Dean Cheng Dean Cheng
Cisco Systems Inc. Cisco Systems Inc.
3700 Cisco Way 3700 Cisco Way
San Jose CA 95134 USA San Jose, CA 95134 USA
Phone: +1 408 527 0677 Phone: +1 408 527 0677
Email: dcheng@cisco.com EMail: dcheng@cisco.com
Kenji Kumaki Kenji Kumaki
KDDI Corporation KDDI Corporation
Garden Air Tower Garden Air Tower
Iidabashi, Chiyoda-ku, Iidabashi, Chiyoda-ku,
Tokyo 102-8460, JAPAN Tokyo 102-8460, JAPAN
Phone: +81-3-6678-3103 Phone: +81-3-6678-3103
Email: ke-kumaki@kddi.com EMail: ke-kumaki@kddi.com
Eiji Oki Eiji Oki
NTT NTT
Midori-cho 3-9-11 Midori-cho 3-9-11
Musashino-shi, Tokyo 180-8585, JAPAN Musashino-shi, Tokyo 180-8585, JAPAN
Email: oki.eiji@lab.ntt.co.jp EMail: oki.eiji@lab.ntt.co.jp
Raymond Zhang Raymond Zhang
BT BT
2160 E. Grand Ave. 2160 E. Grand Ave.
El Segundo, CA 90245 El Segundo, CA 90245
USA USA
raymond.zhang@bt.com EMail: raymond.zhang@bt.com
Renhai Zhang Renhai Zhang
Huawei Technologies Huawei Technologies
No. 3 Xinxi Road, Shangdi, No. 3 Xinxi Road, Shangdi,
Haidian District, Haidian District,
Beijing City, Beijing City,
P. R. China P. R. China
Email: zhangrenhai@huawei.com EMail: zhangrenhai@huawei.com
12. Intellectual Property Statement Editor's Address
Jean-Louis Le Roux
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
EMail: jeanlouis.leroux@orange-ftgroup.com
Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
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on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
skipping to change at page 11, line 29 skipping to change at page 12, line 45
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
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Disclaimer of Validity Acknowledgement
This document and the information contained herein are provided
on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The IETF Trust (2006). This document is subject to the Funding for the RFC Editor function is currently provided by the
rights, licenses and restrictions contained in BCP 78, and except as Internet Society.
set forth therein, the authors retain all their rights.
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