draft-ietf-pce-inter-layer-req-08.txt   draft-ietf-pce-inter-layer-req-09.txt 
Network Working Group T. Takeda (Ed.) Network Working Group T. Takeda (Ed.)
Internet Draft NTT Internet Draft NTT
Category: Informational A. Farrel (Ed.) Category: Informational A. Farrel (Ed.)
Created: October 15, 2008 Old Dog Consulting Created: December 2008 Old Dog Consulting
Expires: April 15, 2009
PCC-PCE Communication and PCE Discovery Requirements for PCC-PCE Communication and PCE Discovery Requirements for
Inter-Layer Traffic Engineering Inter-Layer Traffic Engineering
draft-ietf-pce-inter-layer-req-08.txt draft-ietf-pce-inter-layer-req-09.txt
Status of this Memo Status of this Memo
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have been or will be disclosed, and any of which he or she becomes
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http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
The Path Computation Element (PCE) provides functions of path The Path Computation Element (PCE) provides functions of path
computation in support of traffic engineering in Multi-Protocol Label computation in support of traffic engineering in Multi-Protocol Label
Switching (MPLS) and Generalized MPLS (GMPLS) networks. Switching (MPLS) and Generalized MPLS (GMPLS) networks.
MPLS and GMPLS networks may be constructed from layered client/server MPLS and GMPLS networks may be constructed from layered client/server
networks. It is advantageous for overall network efficiency to networks. It is advantageous for overall network efficiency to
provide end-to-end traffic engineering across multiple network provide end-to-end traffic engineering across multiple network layers.
layers. PCE is a candidate solution for such requirements. PCE is a candidate solution for such requirements.
Generic requirements for a communication protocol between Path Generic requirements for a communication protocol between Path
Computation Clients (PCCs) and PCEs are presented in "PCE Computation Clients (PCCs) and PCEs are presented in "PCE
Communication Protocol Generic Requirements". Generic requirements Communication Protocol Generic Requirements". Generic requirements
for PCE discovery protocol are presented in "Requirements for Path for PCE discovery protocol are presented in "Requirements for Path
Computation Element (PCE) Discovery". Computation Element (PCE) Discovery".
This document complements the generic requirements and presents This document complements the generic requirements and presents
detailed sets of PCC-PCE communication protocol requirements and PCE detailed sets of PCC-PCE communication protocol requirements and PCE
discovery protocol requirements for inter-layer traffic engineering. discovery protocol requirements for inter-layer traffic engineering.
Table of Contents Table of Contents
1. Introduction................................................. 3 1. Introduction...................................................3
1.1. Terminology............................................... 3 1.1. Terminology..................................................3
2. Motivation for PCE-Based Inter-Layer Path Computation........ 4 2. Motivation for PCE-Based Inter-Layer Path Computation..........4
3. PCC-PCE Communication and Discovery Requirements for Inter- 3. PCC-PCE Communication and Discovery Requirements for Inter-Layer
Layer Traffic Engineering.................................... 5 Traffic Engineering...............................................5
3.1. PCC-PCE Communication..................................... 5 3.1. PCC-PCE Communication........................................5
3.1.1. Control of Inter-Layer Path Computation................. 5 3.1.1. Control of Inter-Layer Path Computation....................5
3.1.2. Control of The Type of Path to be Computed.............. 5 3.1.2. Control of The Type of Path to be Computed.................5
3.1.3. Communication of Inter-Layer Constraints................ 7 3.1.3. Communication of Inter-Layer Constraints...................6
3.1.4. Adaptation Capability................................... 7 3.1.4. Adaptation Capability......................................7
3.1.5. Cooperation Between PCEs................................ 7 3.1.5. Cooperation Between PCEs...................................7
3.1.6. Inter-Layer Diverse paths............................... 7 3.1.6. Inter-Layer Diverse paths..................................7
3.2. Capabilities Advertisements for PCE Discovery............. 8 3.2. Capabilities Advertisements for PCE Discovery................7
3.3. Supported Network Models.................................. 8 3.3. Supported Network Models.....................................8
4. Manageability considerations................................. 8 4. Manageability considerations...................................8
4.1. Control of Function and Policy............................ 8 4.1. Control of Function and Policy...............................8
4.2. Information and Data Models............................... 9 4.2. Information and Data Models..................................8
4.3. Liveness Detection and Monitoring......................... 9 4.3. Liveness Detection and Monitoring............................9
4.4. Verifying Correct Operation............................... 9 4.4. Verifying Correct Operation..................................9
4.5. Requirements on Other Protocols and Functional 4.5. Requirements on Other Protocols and Functional Components....9
Components................................................ 9 4.6. Impact on Network Operation.................................10
4.6. Impact on Network Operation.............................. 10 5. Security Considerations.......................................10
5. Security Considerations..................................... 10 6. IANA Considerations...........................................10
6. IANA Considerations......................................... 10 7. Acknowledgments...............................................10
7. Acknowledgments............................................. 10 8. References....................................................10
8. References.................................................. 11 8.1. Normative References........................................10
8.1. Normative Reference...................................... 11 8.2. Informative References......................................11
8.2. Informative Reference.................................... 11 9. Authors' Addresses............................................12
9. Authors' Addresses.......................................... 12
10. Intellectual Property Statement............................ 12
1. Introduction 1. Introduction
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. network graph, and applying computational constraints.
A network may comprise multiple layers. These layers may represent A network may comprise multiple layers. These layers may represent
separations of technologies (e.g., packet switch capable (PSC), time separations of technologies (e.g., packet switch capable (PSC), time
division multiplex (TDM), lambda switch capable (LSC)) [RFC3945], division multiplex (TDM), lambda switch capable (LSC)) [RFC3945],
separation of data plane switching granularity levels (e.g., PSC-1 separation of data plane switching granularity levels (e.g., PSC-1
and PSC-2, or VC4 and VC12) [RFC5212], or a distinction between and PSC-2, or VC4 and VC12) [RFC5212], or a distinction between
client and server networking roles (e.g., commercial or client and server networking roles (e.g., commercial or
administrative separation of client and server networks). In this administrative separation of client and server networks). In this
multi-layer network, LSP in lower layers are used to carry upper- multi-layer network, Label Switched Paths (LSPs) in lower layers are
layer LSPs. The network topology formed by lower-layer LSPs and used to carry upper-layer LSPs. The network topology formed by lower-
advertised to the higher layer is called a Virtual Network Topology layer LSPs and advertised to the higher layer is called a Virtual
(VNT) [RFC5212]. Network Topology (VNT) [RFC5212].
In layered networks under the operation of MPLS-TE and GMPLS In layered networks under the operation of Multiprotocol Label
Switching Traffic Engineering (MPLS-TE) and Generalized MPLS (GMPLS)
protocols, it is important to provide mechanisms to allow global protocols, it is important to provide mechanisms to allow global
optimization of network resources. That is, to take into account all optimization of network resources. That is, to take into account all
layers, rather than optimizing resource utilization at each layer layers, rather than optimizing resource utilization at each layer
independently. This allows better network efficiency to be achieved. independently. This allows better network efficiency to be achieved.
This is what we call Inter-layer traffic engineering. This includes This is what we call Inter-layer traffic engineering. This includes
mechanisms allowing computation of end-to-end paths across layers mechanisms allowing computation of end-to-end paths across layers
(known as inter-layer path computation), and mechanisms for control (known as inter-layer path computation), and mechanisms for control
and management of the VNT by setting up and releasing LSPs in the and management of the VNT by setting up and releasing LSPs in the
lower layers [RFC5212]. lower layers [RFC5212].
Inter-layer traffic engineering is included in the scope of the PCE Inter-layer traffic engineering is included in the scope of the PCE
architecture [RFC4655], and PCE can provide a suitable mechanism for architecture [RFC4655], and PCE can provide a suitable mechanism for
resolving inter-layer path computation issues. The applicability of resolving inter-layer path computation issues. The applicability of
the PCE-based path computation architecture to inter-layer traffic the PCE-based path computation architecture to inter-layer traffic
engineering is described in [PCE-INTER-LAYER-FRWK]. engineering is described in [PCE-INTER-LAYER-FRWK].
This document presents sets of PCC-PCE communication protocol (PCECP) This document presents sets of requirements for communication between
and PCE Discovery protocol requirements for inter-layer traffic path computation clients (PCCs) and PCEs using the PCE protocol
engineering. It supplements the generic requirements documented in (PCEP), and for PCE discovery for inter-layer traffic engineering. It
[RFC4657] and [RFC4674]. supplements the generic requirements documented in [RFC4657] and
[RFC4674].
1.1. Terminology 1.1. Terminology
LSP: Label Switched Path. LSP: Label Switched Path.
LSR: Label Switching Router. LSR: Label Switching Router.
PCC: Path Computation Client: any client application requesting a PCC: Path Computation Client, any client application requesting a
path computation to be performed by a Path Computation Element. path computation to be performed by a Path Computation Element.
PCE: Path Computation Element: an entity (component, application or PCE: Path Computation Element, an entity (component, application or
network node) that is capable of computing a network path or route network node) that is capable of computing a network path or route
based on a network graph and applying computational constraints. based on a network graph and applying computational constraints.
PCECP: PCE Communication Protocol, a protocol for communication PCEP: PCE Communication Protocol, a protocol for communication
between PCCs and PCEs. between PCCs and PCEs.
TED: Traffic Engineering Database which contains the topology and
resource information of the domain. The TED may be fed by IGP
extensions or potentially by other means.
TE LSP: Traffic Engineering Label Switched Path.
TE LSP head-end: head/source/ingress of the TE LSP.
TE LSP tail-end: tail/destination/egress of the TE LSP.
Although this requirements document is an informational document not Although this requirements document is an informational document not
a protocol specification, the key words "MUST", "MUST NOT", a protocol specification, the key words "MUST", "MUST NOT",
"REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
interpreted as described in RFC 2119 [RFC2119] for clarity of interpreted as described in RFC 2119 [RFC2119] for clarity of
requirement specification. requirement specification.
2. Motivation for PCE-Based Inter-Layer Path Computation 2. Motivation for PCE-Based Inter-Layer Path Computation
[RFC4206] defines a way to signal a Multiprotocol Label Switching [RFC4206] defines a way to signal an MPLS or a GMPLS LSP with an
(MPLS) or Generalized MPLS (GMPLS) LSP with an explicit route in a explicit route in a higher layer of a network that includes hops
higher layer of a network that includes hops traversed by LSPs in traversed by LSPs in lower layers of the network. The computation of
lower layers of the network. The computation of end-to-end paths end-to-end paths across layers is called Inter-Layer Path Computation.
across layers is called Inter-Layer Path Computation.
An LSR in the higher-layer might not have information on the topology An LSR in the higher layer might not have information on the topology
of lower-layers, particularly in an overlay or augmented model, and of lower layers, particularly in an overlay or augmented model, and
hence might not be able to compute an end-to-end path across layers. hence might not be able to compute an end-to-end path across layers.
PCE-based inter-layer path computation, consists of relying on one or PCE-based inter-layer path computation, consists of relying on one or
more PCEs to compute an end-to-end path across layers. This could more PCEs to compute an end-to-end path across layers. This could
rely on a single PCE path computation where the PCE has topology rely on a single PCE path computation where the PCE has topology
information about multiple layers and can directly compute an end-to- information about multiple layers and can directly compute an end-to-
end path across layers considering the topology of all of the layers. end path across layers considering the topology of all of the layers.
Alternatively, the inter-layer path computation could be performed as Alternatively, the inter-layer path computation could be performed as
a multiple PCE computation where each member of a set of PCEs has a multiple PCE computation where each member of a set of PCEs has
information about the topology of one or more layers, but not all information about the topology of one or more layers, but not all
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Consider a two-layer network where the higher-layer network is a Consider a two-layer network where the higher-layer network is a
packet-based IP/MPLS or GMPLS network and the lower-layer network is packet-based IP/MPLS or GMPLS network and the lower-layer network is
a GMPLS optical network. An ingress LSR in the higher-layer network a GMPLS optical network. An ingress LSR in the higher-layer network
tries to set up an LSP to an egress LSR also in the higher-layer tries to set up an LSP to an egress LSR also in the higher-layer
network across the lower-layer network, and needs a path in the network across the lower-layer network, and needs a path in the
higher-layer network. However, suppose that there is no TE link higher-layer network. However, suppose that there is no TE link
between border LSRs, which are located on the boundary between the between border LSRs, which are located on the boundary between the
higher-layer and lower-layer networks, and that the ingress LSR does higher-layer and lower-layer networks, and that the ingress LSR does
not have topology visibility in the lower layer. If a single-layer not have topology visibility in the lower layer. If a single-layer
path computation is applied for the higher-layer, the path path computation is applied for the higher layer, the path
computation fails. On the other hand, inter-layer path computation is computation fails. On the other hand, inter-layer path computation is
able to provide a route in the higher-layer and a suggestion that a able to provide a route in the higher layer and a suggestion that a
lower-layer LSP be setup between border LSRs, considering both layers lower-layer LSP be setup between border LSRs, considering both layers
as TE topologies. as TE topologies.
Further discussion of the application of PCE to inter-layer path Further discussion of the application of PCE to inter-layer path
computation can be found in [PCE-INTER-LAYER-FRWK]. computation can be found in [PCE-INTER-LAYER-FRWK].
3. PCC-PCE Communication and Discovery Requirements for Inter-Layer 3. PCC-PCE Communication and Discovery Requirements for Inter-Layer
Traffic Engineering Traffic Engineering
This section sets out additional requirements specific to the This section sets out additional requirements specific to the
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The PCC-PCE communication protocol MUST allow requests and replies The PCC-PCE communication protocol MUST allow requests and replies
for inter-layer path computation. for inter-layer path computation.
This requires no additional messages, but implies the following This requires no additional messages, but implies the following
additional constraints to be added to the PCC-PCE communication additional constraints to be added to the PCC-PCE communication
protocol. protocol.
3.1.1. Control of Inter-Layer Path Computation 3.1.1. Control of Inter-Layer Path Computation
A request from a PCC to a PCE SHOULD indicate whether inter-layer A request from a PCC to a PCE MUST support the inclusion of an
path computation is allowed. In the absence of such an indication, optional indication of whether inter-layer path computation is
the default is that inter-layer path computation is not allowed. allowed. In the absence of such an indication, the default is that
inter-layer path computation is not allowed.
Therefore, a request from a PCC to a PCE MUST support the inclusion
of such an indication.
3.1.2. Control of The Type of Path to be Computed 3.1.2. Control of The Type of Path to be Computed
The PCE computes and returns a path to the PCC that the PCC can use The PCE computes and returns a path to the PCC that the PCC can use
to build a higher-layer or lower-layer LSP once converted to an to build a higher-layer or lower-layer LSP once converted to an
Explicit Route Object (ERO) for use in RSVP-TE signaling. There are Explicit Route Object (ERO) for use in RSVP-TE signaling. There are
two options [PCE-INTER-LAYER-FRWK]. two options [PCE-INTER-LAYER-FRWK].
- Option 1: Mono-layer path. The PCE computes a "mono layer" path, - Option 1: Mono-layer path. The PCE computes a "mono layer" path,
i.e., a path that includes only TE-links from the same layer. i.e., a path that includes only TE-links from the same layer.
- Option 2: Multi-layer path. The PCE computes a "multi-layer" path, - Option 2: Multi-layer path. The PCE computes a "multi-layer" path,
i.e., a path that includes TE links from distinct layers [RFC4206]. i.e., a path that includes TE links from distinct layers [RFC4206].
It may be necessary or desirable for a PCC to control the type of It may be necessary or desirable for a PCC to control the type of
path that is produced by a PCE. For example, a PCC may know that it path that is produced by a PCE. For example, a PCC may know that it
is not possible for technological or policy reasons to signal a is not possible for technological or policy reasons to signal a
multi-layer path and that a mono-layer path is required, or the PCC multi-layer path and that a mono-layer path is required, or the PCC
may know that it does not wish the layer border node to have control may know that it does not wish the layer border node to have control
of path computation. In order to make this level of control possible, of path computation. In order to make this level of control possible,
the PCECP MUST allow the PCC to select the path types that may be the PCEP MUST allow the PCC to select the path types to be computed,
returned by choosing one or more from the following list: and that may be returned, by choosing one or more from the following
list:
- A mono-layer path that is specified by strict hop(s). The path may - A mono-layer path that is specified by strict hop(s). The path may
include virtual TE link(s). include virtual TE link(s).
- A mono-layer path that includes loose hop(s). - A mono-layer path that includes loose hop(s).
- A multi-layer path that can include the path (as strict or loose - A multi-layer path that can include the path (as strict or loose
hops) of one or more lower-layer LSPs not yet established. hops) of one or more lower-layer LSPs not yet established.
The path computation response from a PCE to a PCC MUST report the The path computation response from a PCE to a PCC MUST report the
type of path computed, and where a multi-layer path is returned, type of path computed, and where a multi-layer path is returned, PCEP
PCECP MUST support the inclusion, as part of end-to-end path, of the MUST support the inclusion, as part of end-to-end path, of the path
path of the lower-layer LSPs to be established. of the lower-layer LSPs to be established.
If a response message from a PCE to PCC carries a mono-layer path If a response message from a PCE to PCC carries a mono-layer path
that is specified by strict hops but includes virtual TE link(s), or that is specified by strict hops but includes virtual TE link(s), or
includes loose hop(s), or carries a multi-layer path that can include includes loose hop(s), or carries a multi-layer path that can include
the complete path of one or more lower-layer LSPs not yet the complete path of one or more lower-layer LSPs not yet established,
established, the signaling of the higher-layer LSP may trigger the the signaling of the higher-layer LSP may trigger the establishment
establishment of the lower-layer LSPs (nested signaling). The nested of the lower-layer LSPs (triggered signaling). The triggered
signaling may increase the higher-layer connection setup latency. An signaling may increase the higher-layer connection setup latency. An
ingress LSR for the higher-layer LSP, or a PCC, needs to know whether ingress LSR for the higher-layer LSP, or a PCC, needs to know whether
nested signaling is required or not. triggered signaling is required or not.
A request from a PCC to a PCE MUST allow indicating whether nested A request from a PCC to a PCE MUST allow indicating whether triggered
signaling is acceptable or not. signaling is acceptable or not.
A response from a PCE to a PCC MUST allow indicating whether the A response from a PCE to a PCC MUST allow indicating whether the
computed path triggers nested signaling or not. computed path requires triggered signaling or not.
Note that a nead-end node may be present in multiple layers. Thus, Note that a PCE may not be able to distinguish virtual TE links from
regular TE links. In such cases, even if a request from a PCC to a
PCE indicates that triggered signaling is not acceptable, a PCE may
choose virtual TE links in path computation. Therefore, when a
network uses virtual TE links and a PCE is not able to distinguish
virtual TE links from regular TE links, it MUST be understood that a
PCE may choose virtual TE links even if a request from a PCC to a PCE
indicates triggered signaling is not acceptable.
Also note that an ingress LSR may be present in multiple layers. Thus,
when a mono-layer path is requested or supplied, PCEP MUST be able to when a mono-layer path is requested or supplied, PCEP MUST be able to
indicate the required/provided path layer. indicate the required/provided path layer.
3.1.3. Communication of Inter-Layer Constraints 3.1.3. Communication of Inter-Layer Constraints
A request from a PCC to a PCE MUST support the inclusion of A request from a PCC to a PCE MUST support the inclusion of
constraints for a multi-layer path. This includes control over which constraints for a multi-layer path. This includes control over which
network layers may, must, or must not be included in the computed network layers may, must, or must not be included in the computed
path. Such control may be expressed in terms of the switching types path. Such control may be expressed in terms of the switching types
of the layer networks. Furthermore, it may be desirable to constrain of the layer networks.
the number of layer boundaries crossed (i.e., the number of
adaptations performed on the end-to-end path), so PCEP SHOULD include Furthermore, it may be desirable to constrain the number of layer
a constraint or objective function to minimize or cap the number of boundaries crossed (i.e., the number of adaptations performed on the
adaptations on a path, and a mechanism to report that number when a end-to-end path), so PCEP SHOULD include a constraint or objective
path is supplied. function to minimize or cap the number of adaptations on a path, and
a mechanism to report that number when a path is supplied.
The path computation request MUST also allow for different objective The path computation request MUST also allow for different objective
functions to be applied within different network layers. For example, functions to be applied within different network layers. For example,
the path in a packet-network may need to be optimized for least delay the path in a packet-network may need to be optimized for least delay
using the IGP metric as a measure of delay, while the path in an using the IGP metric as a measure of delay, while the path in an
under-lying TDM network might be optimized for fewest hops. under-lying TDM network might be optimized for fewest hops.
3.1.4. Adaptation Capability 3.1.4. Adaptation Capability
It MUST be possible for the path computation request to indicate the It MUST be possible for the path computation request to indicate the
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diverse inter-Layer paths. A request from a PCC to a PCE MUST support diverse inter-Layer paths. A request from a PCC to a PCE MUST support
the inclusion of multiple path requests, with the desired level of the inclusion of multiple path requests, with the desired level of
diversity at each layer (link, node, SRLG). diversity at each layer (link, node, SRLG).
3.2. Capabilities Advertisements for PCE Discovery 3.2. Capabilities Advertisements for PCE Discovery
In the case where there are several PCEs with distinct capabilities In the case where there are several PCEs with distinct capabilities
available, a PCC has to select one or more appropriate PCEs. available, a PCC has to select one or more appropriate PCEs.
For that purpose, the PCE discovery mechanism MAY support the For that purpose, the PCE discovery mechanism MAY support the
disclosure of some detailed PCE capabilities. disclosure of some detailed PCE capabilities. A PCE MAY (to be
A PCE MAY (to be consistent with the above text and RFC4674) be able consistent with the above text and RFC4674) be able to advise the
to advise the following inter-layer-path-computation-related PCE following inter-layer-path-computation-related PCE capabilities:
capabilities:
- Support for inter-layer path computation - Support for inter-layer path computation
- Support for mono-layer/multi-layer paths - Support for mono-layer/multi-layer paths
- Support for Adaptation Capability - Support for inter-layer constraints
- Support for Inter-PCE communication - Support for adaptation capability
- Support for inter-PCE communication
- Support for inter-layer diverse path computation - Support for inter-layer diverse path computation
3.3. Supported Network Models 3.3. Supported Network Models
The PCC-PCE communication protocol SHOULD allow several architectural The PCC-PCE communication protocol SHOULD allow several architectural
alternatives for interworking between MPLS and GMPLS networks: alternatives for interworking between MPLS and GMPLS networks:
overlay, integrated and augmented models [RFC3945], [RFC5145], overlay, integrated and augmented models [RFC3945], [RFC5145],
[RFC5146]. [RFC5146].
4. Manageability considerations 4. Manageability considerations
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level of support is changed, this SHOULD be re-advertised. level of support is changed, this SHOULD be re-advertised.
However, a PCE MAY also elect to support inter-layer computations, However, a PCE MAY also elect to support inter-layer computations,
but not to advertise the fact, so that only those PCCs configured to but not to advertise the fact, so that only those PCCs configured to
know of the PCE and its capabilities can use it. know of the PCE and its capabilities can use it.
Support for, and advertisement of support for, inter-layer path Support for, and advertisement of support for, inter-layer path
computation MAY be subject to policy and a PCE MAY hide its inter- computation MAY be subject to policy and a PCE MAY hide its inter-
layer capabilities from certain PCCs by not advertising them through layer capabilities from certain PCCs by not advertising them through
the discovery protocol, and not reporting them to the specific PCCs the discovery protocol, and not reporting them to the specific PCCs
in any PCECP capabilities exchange. Further, a PCE MAY be directed by in any PCEP capabilities exchange. Further, a PCE MAY be directed by
policy to refuse an inter-layer path computation request for any policy to refuse an inter-layer path computation request for any
reason including, but not limited to, the identity of the PCC that reason including, but not limited to, the identity of the PCC that
makes the request. makes the request.
4.2. Information and Data Models 4.2. Information and Data Models
PCECP protocol extensions to support inter-layer computations MUST be PCEP extensions to support inter-layer computations MUST be
accompanied by MIB objects for the control and monitoring of the accompanied by MIB objects for the control and monitoring of the
protocol and of the PCE that performs the computations. The MIB protocol and of the PCE that performs the computations. The MIB
objects MAY be provided in the same MIB module as used for general objects MAY be provided in the same MIB module as used for general
PCECP control and monitoring [PCEP-MIB] or MAY be provided in a new PCEP control and monitoring [PCEP-MIB] or MAY be provided in a new
MIB module. MIB module.
The MIB objects MUST provide the ability to control and monitor all The MIB objects MUST provide the ability to control and monitor all
aspects of PCECP relevant to inter-layer path computation. aspects of PCEP relevant to inter-layer path computation.
4.3. Liveness Detection and Monitoring 4.3. Liveness Detection and Monitoring
No changes are necessary to the liveness detection and monitoring No changes are necessary to the liveness detection and monitoring
requirements as already embodied in [RFC4657]. It should be noted, requirements as already embodied in [RFC4657]. It should be noted,
however, that inter-layer path computations might require extended however, that inter-layer path computations might require extended
cooperation between PCEs (as is also the case for inter-AS and inter- cooperation between PCEs (as is also the case for inter-AS and inter-
area computations) and so the liveness detection and monitoring area computations) and so the liveness detection and monitoring
SHOULD be applied to each PCECP communication and aggregated to SHOULD be applied to each PCEP communication and aggregated to report
report the behavior of an individual PCECP request to the originating the behavior of an individual PCECP request to the originating PCC.
PCC.
In particular, where a request is forwarded between multiple PCEs In particular, where a request is forwarded between multiple PCEs
neither the PCC not the first PCE can monitor the liveness of all neither the PCC nor the first PCE can monitor the liveness of all
inter-PCE-PCE connections or of the PCEs themselves. In this case, inter-PCE-PCE connections or of the PCEs themselves. In this case,
suitable performance of the original PCECP request relies on each PCE suitable performance of the original PCEP request relies on each PCE
operating correct monitoring procedures and correlating any failures operating correct monitoring procedures and correlating any failures
back to the PCECP requests that are outstanding. These requirements back to the PCEP requests that are outstanding. These requirements
are no different from those for any cooperative PCE usage, and are are no different from those for any cooperative PCE usage, and are
expected to be already covered by general, and by inter-AS and inter- expected to be already covered by general, and by inter-AS and inter-
area implementations. area implementations. Such a procedure is specified in [BRPC].
In addition, [PCEP-MON] specifies mechanisms to gather various state
metrics along the path computation chain.
4.4. Verifying Correct Operation 4.4. Verifying Correct Operation
There are no additional requirements beyond those expressed in There are no additional requirements beyond those expressed in
[RFC4657] for verifying the correct operation of the PCECP. Note that [RFC4657] for verifying the correct operation of the PCEP. Note that
verification of the correct operation of the PCE and its algorithms verification of the correct operation of the PCE and its algorithms
is out of scope for the protocol requirements, but a PCC MAY send the is out of scope for the protocol requirements, but a PCC MAY send the
same request to more than one PCE and compare the results. same request to more than one PCE and compare the results.
4.5. Requirements on Other Protocols and Functional Components 4.5. Requirements on Other Protocols and Functional Components
A PCE operates on a topology graph that may be built using A PCE operates on a topology graph that may be built using
information distributed by TE extensions to the routing protocol information distributed by TE extensions to the routing protocol
operating within the network. In order that the PCE can select a operating within the network. In order that the PCE can select a
suitable path for the signaling protocol to use to install the inter- suitable path for the signaling protocol to use to install the inter-
skipping to change at page 11, line 7 skipping to change at page 10, line 49
7. Acknowledgments 7. Acknowledgments
We would like to thank Kohei Shiomoto, Ichiro Inoue, and Dean Cheng We would like to thank Kohei Shiomoto, Ichiro Inoue, and Dean Cheng
for their useful comments. Thanks to members of ITU-T Study Group 15 for their useful comments. Thanks to members of ITU-T Study Group 15
Question 14 for their constructive comments during the liaison Question 14 for their constructive comments during the liaison
process. process.
8. References 8. References
8.1. Normative Reference 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
requirements levels", RFC 2119, March 1997. requirements levels", RFC 2119, March 1997.
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
Architecture", RFC 3945, October 2004. Architecture", RFC 3945, October 2004.
[RFC4206] Kompella, K., and Rekhter, Y., "Label Switched Paths (LSP) [RFC4206] Kompella, K., and Rekhter, Y., "Label Switched Paths (LSP)
Hierarchy with Generalized Multi-Protocol Label Switching Hierarchy with Generalized Multi-Protocol Label Switching
(GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005. (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.
8.2. Informative Reference 8.2. Informative References
[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 Element (PCE)-Based Architecture", RFC 4655, September
2006. 2006.
[RFC4657] J. Ash, J.L Le Roux et al., " Path Computation Element [RFC4657] J. Ash, J.L Le Roux et al., " Path Computation Element
(PCE) Communication Protocol Generic Requirements", RFC (PCE) Communication Protocol Generic Requirements", RFC
4657, September 2006. 4657, September 2006.
[RFC4674] JL Le Roux et al., "Requirements for Path Computation [RFC4674] JL Le Roux et al., "Requirements for Path Computation
skipping to change at page 12, line 5 skipping to change at page 11, line 44
(PCEP) Management Information Base", draft-kkoushik-pce- (PCEP) Management Information Base", draft-kkoushik-pce-
pcep-mib (work in progress). pcep-mib (work in progress).
[RFC5145] K. Shiomoto, "Framework for MPLS-TE to GMPLS Migration", [RFC5145] K. Shiomoto, "Framework for MPLS-TE to GMPLS Migration",
RFC 5145, March 2008. RFC 5145, March 2008.
[RFC5146] K. Kumaki et al., "Interworking Requirements to Support [RFC5146] K. Kumaki et al., "Interworking Requirements to Support
Operation of MPLS-TE over GMPLS Networks", RFC 5146, March Operation of MPLS-TE over GMPLS Networks", RFC 5146, March
2008. 2008.
[BRPC] JP. Vasseur (Ed.), "A Backward Recursive PCE-based
Computation (BRPC) Procedure To Compute Shortest
Constrained Inter-domain Traffic Engineering Label Switched
Paths", draft-ietf-pce-brpc (work in progress).
[PCEP-MON] JP. Vasseur (Ed.), "A set of monitoring tools for Path
Computation Element based Architecture", draft-ietf-pce-
Monitoring (work in progress).
9. Authors' Addresses 9. Authors' Addresses
Eiji Oki Eiji Oki
University of Electro-Communications University of Electro-Communications
Tokyo Tokyo
Japan Japan
Email: oki@ice.uec.ac.jp Email: oki@ice.uec.ac.jp
Jean-Louis Le Roux Jean-Louis Le Roux
France Telecom R&D, France Telecom R&D,
skipping to change at page 12, line 37 skipping to change at page 12, line 37
Adrian Farrel Adrian Farrel
Old Dog Consulting Old Dog Consulting
Email: adrian@olddog.co.uk Email: adrian@olddog.co.uk
Tomonori Takeda Tomonori Takeda
NTT NTT
3-9-11 Midori-cho, 3-9-11 Midori-cho,
Musashino-shi, Tokyo 180-8585, Japan Musashino-shi, Tokyo 180-8585, Japan
Email: takeda.tomonori@lab.ntt.co.jp Email: takeda.tomonori@lab.ntt.co.jp
10. Intellectual Property Statement Full Copyright Statement
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