A Forward-Search P2MP TE LSP Inter-Domain Path Computation
draft-chen-pce-forward-search-p2mp-path-21
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Huaimo Chen
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PCE Working Group H. Chen
Internet-Draft Futurewei
Intended status: Standards Track 10 January 2022
Expires: 14 July 2022
A Forward-Search P2MP TE LSP Inter-Domain Path Computation
draft-chen-pce-forward-search-p2mp-path-21
Abstract
This document presents a forward search procedure for computing a
path for a Point-to-MultiPoint (P2MP) Traffic Engineering (TE) Label
Switched Path (LSP) crossing a number of domains through using
multiple Path Computation Elements (PCEs). In addition, extensions
to the Path Computation Element Communication Protocol (PCEP) for
supporting the forward search procedure are described.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 14 July 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Conventions Used in This Document . . . . . . . . . . . . . . 4
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Forward Search P2MP Path Computation . . . . . . . . . . . . 4
5.1. Overview of Procedure . . . . . . . . . . . . . . . . . . 5
5.2. Description of Procedure . . . . . . . . . . . . . . . . 5
5.3. Processing Request and Reply Messages . . . . . . . . . . 8
6. Comparing to BRPC . . . . . . . . . . . . . . . . . . . . . . 9
7. Extensions to PCEP . . . . . . . . . . . . . . . . . . . . . 9
7.1. RP Object Extension . . . . . . . . . . . . . . . . . . . 10
7.2. PCE Object . . . . . . . . . . . . . . . . . . . . . . . 11
7.3. Candidate Node List Object . . . . . . . . . . . . . . . 11
7.4. Node Flags Object . . . . . . . . . . . . . . . . . . . . 12
7.5. Request Message Extension . . . . . . . . . . . . . . . . 13
7.6. Reply Message Extension . . . . . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9.1. Request Parameter Bit Flags . . . . . . . . . . . . . . . 14
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 14
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
11.1. Normative References . . . . . . . . . . . . . . . . . . 15
11.2. Informative References . . . . . . . . . . . . . . . . . 15
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
RFC 4105 "Requirements for Inter-Area MPLS TE" lists the requirements
for computing a shortest path for a TE LSP crossing multiple IGP
areas; and RFC 4216 "MPLS Inter-Autonomous System (AS) TE
Requirements" describes the requirements for computing a shortest
path for a TE LSP crossing multiple ASes. RFC 5671 "Applicability of
PCE to P2MP MPLS and GMPLS TE" examines the applicability of PCE to
path computation for P2MP TE LSPs in MPLS and GMPLS networks.
This document presents a forward search procedure to address these
requirements for computing a path for a P2MP TE LSP crossing domains
through using multiple Path Computation Elements (PCEs).
The procedure is called "Forward Search Shortest P2MP LSP Path
Crossing Domains" or FSPC for short. The major characteristics of
this procedure for computing a path for a P2MP TE LSP from a source
node to a number of destination nodes crossing multiple domains
include the following three ones.
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1. It guarantees that the path computed from the source node to the
destination nodes is shortest.
2. It does not depend on any domain path tree or domain sequences
from the source node to the destination nodes.
3. Navigating a mesh of domains is simple and efficient.
2. Terminology
ABR: Area Border Router. Routers used to connect two IGP areas
(areas in OSPF or levels in IS-IS).
ASBR: Autonomous System Border Router. Routers used to connect
together ASes of the same or different service providers via one or
more inter-AS links.
Boundary Node (BN): a boundary node is either an ABR in the context
of inter-area Traffic Engineering or an ASBR in the context of inter-
AS Traffic Engineering.
Entry BN of domain(n): a BN connecting domain(n-1) to domain(n) along
the path found from the source node to the BN, where domain(n-1) is
the previous hop domain of domain(n).
Exit BN of domain(n): a BN connecting domain(n) to domain(n+1) along
the path found from the source node to the BN, where domain(n+1) is
the next hop domain of domain(n).
Inter-area TE LSP: A TE LSP that crosses an IGP area boundary.
Inter-AS TE LSP: A TE LSP that crosses an AS boundary.
LSP: Label Switched Path.
LSR: Label Switching Router.
PCC: Path Computation Client. Any client application requesting a
path computation to be performed by a Path Computation Element.
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.
PCE(i) is a PCE with the scope of domain(i).
TED: Traffic Engineering Database.
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This document uses terminologies defined in RFC5440.
3. 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.
4. Requirements
This section summarizes the requirements specific for computing a
path for a Traffic Engineering (TE) LSP crossing multiple domains
(areas or ASes). More requirements for Inter-Area and Inter-AS MPLS
Traffic Engineering are described in RFC 4105 and RFC 4216.
A number of requirements specific for a solution to compute a path
for a TE LSP crossing multiple domains is listed as follows:
1. The solution SHOULD provide the capability to compute a shortest
path dynamically, satisfying a set of specified constraints
across multiple IGP areas.
2. The solution MUST provide the ability to reoptimize in a
minimally disruptive manner (make before break) an inter-area TE
LSP, should a more optimal path appear in any traversed IGP area.
3. The solution SHOULD provide mechanism(s) to compute a shortest
end-to-end path for a TE LSP crossing multiple ASes and
satisfying a set of specified constraints dynamically.
4. Once an inter-AS TE LSP has been established, and should there be
any resource or other changes inside anyone of the ASes, the
solution MUST be able to re-optimize the LSP accordingly and non-
disruptively, either upon expiration of a configurable timer or
upon being triggered by a network event or a manual request at
the TE tunnel Head-End.
5. Forward Search P2MP Path Computation
This section gives an overview of the forward search path computation
procedure (FSPC) to satisfy the requirements for computing a path for
a P2MP TE LSP crossing multiple domains described above and describes
the procedure in details.
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5.1. Overview of Procedure
Simply speaking, the idea of FSPC for computing a path for an MPLS TE
P2MP LSP crossing multiple domains from a source node to a number of
destination nodes includes:
Start from the source node and the source domain.
Consider the optimal path segment from the source node to every exit
boundary and destination node of the source domain as a special link;
Consider the optimal path segment from an entry boundary node to
every exit boundary node and destination node of a domain as a
special link; and the optimal path segment is computed as needed.
The whole topology consisting of many domains can be considered as a
special virtual topology, which contains those special links and the
inter-domain links.
Compute a shortest path in this special topology from the source node
to the multiple destination nodes using CSPF.
FSPC running at any PCE just grows the result path list/tree in the
same way as normal CSPF on the special virtual topology. When the
result path list/tree reaches all the destination nodes, the shortest
path from the source node to the destination nodes is found and a
PCRep message with the path is sent to the PCE/PCC that sends the
PCReq message eventually.
5.2. Description of Procedure
Suppose that we have the following variables:
A current PCE named as CurrentPCE which is currently computing the
path.
A candidate node list named as CandidateNodeList, which contains the
nodes to each of which the temporary optimal path from the source
node is currently found and satisfies a set of given constraints.
Each node C in CandidateNodeList has the following information:
* the cost of the path from the source node to node C,
* the previous hop node P and the link between P and C,
* the PCE responsible for C (i.e., the PCE responsible for the
domain containing C. Alternatively, we may use the domain instead
of the PCE.), and
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* the flags for C.
The flags include:
* bit D indicating that C is a Destination node if it is set;
* bit S indicating that C is the Source node if it is set;
* bit E indicating that C is an Exit boundary node if it is set;
* bit I indicating that C is an entry boundary node if it is set;
and
* bit T indicating that C is on result path Tree if it is set.
The nodes in CandidateNodeList are ordered by path cost.
Initially, CandidateNodeList contains a Source Node, with path cost
0, PCE responsible for the source domain, and flags with S bit set.
It also contains every destination node, with path cost infinity and
flags with D bit set.
A result path list or tree named as ResultPathTree, which contains
the shortest paths from the source node to the boundary nodes and
destination nodes. Initially, ResultPathTree is empty.
Alternatively, the result path list or tree can be combined into the
candidate node list. We may set bit T to one in the node flags for
the candidate node when grafting it into the existing result path
list or tree. Thus all the candidate nodes with bit T set to one in
the candidate list constitute the result path tree or list.
FSPC for computing a path for an MPLS TE P2MP LSP crossing a number
of domains from a source node to a number of destination nodes can be
described as follows:
Initially, a PCC sends a PCE responsible for the source domain a
request with CandidateNodeList and ResultPathTree initialized.
When the PCE responsible for a domain (called current domain)
receives a request for computing the path for the MPLS TE P2MP LSP,
it checks whether the current PCE is the PCE responsible for the node
C with the minimum cost in the CandidateNodeList. If it is, then
remove C from CandidateNodeList and graft it into ResultPathTree
(i.e., set flag bit T of node C to one); otherwise, a PCReq message
is sent to the PCE for node C.
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Suppose that node C is in the current domain. The ResultPathTree is
built from C in the following steps.
If node C is a destination node (i.e., the Destination Node (D) bit
in the Flags is set), then check whether the path cost to node C is
infinity. If it is, then we can not find any path for the P2MP LSP,
and a repply message with failure reasons is sent; otherwise, if all
the destinations are on the result path tree, then the shortest path
is found and a PCRep message with the path is sent to the PCE/PCC
which sends the request to the current PCE.
If node C is an entry boundary node or the source node, then the
optimal path segments from node C to every destination node and every
exit boundary node of the current domain that is not on the result
path tree and satisfies the given constraints are computed through
using CSPF and as special links.
For every node N connected to node C through a special link (i.e.,
the optimal path segment satisfying the given constraints), it is
merged into CandidateNodeList. The cost to node N is the sum of the
cost to node C and the cost of the special link (i.e., the path
segment) between C and N. If node N is not in the candidate node
list, then node N is added into the list with the cost to node N,
node C as its previous hop node and a PCE for node N. The PCE for
node N is the current PCE if node N is an ASBR; otherwise (node N is
an ABR, an exit boundary node of the current domain and an entry
boundary node of the domain next to the current domain) the PCE for
node N is the PCE for the next domain. If node N is in the candidate
node list and the cost to node N through node C is less than the cost
to node N in the list, then replace the cost to node N in the list
with the cost to node N through node C and the previous hop to node N
in the list with node C.
If node C is an exit boundary node and there are inter-domain links
connecting to it (i.e., node C is an ASBR) and satisfying the
constraints, then for every node N connecting to C, satisfying the
constraints and not on the result path tree, it is merged into the
candidate node list. The cost to node N is the sum of the cost to
node C and the cost of the link between C and N. If node N is not in
the candidate node list, then node N is added into the list with the
cost to node N, node C as its previous hop node and the PCE for node
N. If node N is in the candidate node list and the cost to node N
through node C is less than the cost to node N in the list, then
replace the cost to node N in the list with the cost to node N
through node C and the previous hop to node N in the list with node
C.
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If the CurrentPCE is the same as the PCE for the node D with the
minimum cost in CandidateNodeList, then the node D is removed from
CandidateNodeList and grafted to ResultPathTree (i.e., set flag bit T
of node D to one), and the above steps are repeated; otherwise, a
request message is to be sent to the PCE for node D.
5.3. Processing Request and Reply Messages
In this section, we describe the processing of the request and reply
messages with Forward search bit set for FSPC. Each of the request
and reply messages mentioned below has its Forward search bit set
even though we do not indicate this explicitly.
In the case that a reply message is a final reply, which contains the
optimal path from the source to the destination, the reply message is
sent toward the PCC along the path that the request message goes from
the PCC to the current PCE in reverse direction.
In the case that a request message is to be sent to the PCE for node
D with the minimum cost in the candidate node list and there is a PCE
session between the current domain and the next domain containing
node D, the current PCE sends the PCE for node D through the session
a request message with the source node, the destination node,
CandidateNodeList and ResultPathTree.
In the case that a request message is to be sent to the PCE for node
D and there is not any PCE session between the current PCE and the
PCE for node D, a reply message is sent toward a branch point on the
result path tree from the current domain along the path that the
request message goes from the PCC to the current PCE in reverse
direction. From the branch point, there is a downward path to the
domain containing the previous hop node of node D on the result path
tree and to the domain containing node D. At this branch point, the
request message is sent to the PCE for node D along the downward
path.
Suppose that node D has the minimum cost in CandidateNodeList when a
PCE receives a request message or a reply message containing
CandidateNodeList.
When a PCE (current PCE) for a domain (current domain) receives a
reply message PCRep, it checks whether the reply is a final reply
with the optimal path from the source to the destination. If the
reply is the final reply, the current PCE sends the reply to the PCE
that sends the request to the current PCE; otherwise, it checks
whether there is a path from the current domain to the domain
containing the previous hop node of node D on ResultPathTree and to
the domain containing node D. If there is a path, the PCE sends a
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request PCReq to the PCE responsible for the next domain along the
path; otherwise, it sends a reply PCRep to the PCE that sends the
request to the current PCE.
When a PCE receives a request PCReq, it checks whether the current
domain contains node D. If it does, then node D is removed from
CandidateNodeList and grafted to ResultPathTree (i.e., set flag bit T
of node D to one), and the above steps in the previous sub section
are repeated; otherwise, the PCE sends a request PCReq to the PCE
responsible for the next domain along the path from the current
domain to the domain containing the previous hop node of node D on
ResultPathTree and to the domain containing node D.
6. Comparing to BRPC
RFC 5441 describes the Backward Recursive Path Computation (BRPC)
algorithm or procedure for computing an MPLS TE P2P LSP path from a
source node to a destination node crossing multiple domains.
Comparing to BRPC, there are a number of differences between BRPC and
the Forward-Search P2MP TE LSP Inter-Domain Path Computation (FSPC).
Some of the differences are briefed below.
At first, BRPC is for computing a shortest path from a source node to
a destination node crossing multiple domains. FSPC is for computing
a shortest path from a source node to a number of destination nodes
crossing multiple domains.
Secondly, for BRPC to compute a shortest path from a source node to a
destination node crossing multiple domains, we MUST provide a
sequence of domains from the source node to the destination node to
BRPC in advance. FSPC does not need any sequence of domains for
computing a shortest inter-domain P2MP path.
Moreover, for a given sequence of domains domain(1), domain(2), ... ,
domain(n), BRPC searches the shortest path from domain(n), to
domain(n-1), until domain(1). Thus it is hard for BRPC to be
extended for computing a shortest path from a source node to a number
of destination nodes crossing multiple domains. FSPC calculates a
shortest path in a special topology from the source node to the
destination nodes using CSPF.
7. Extensions to PCEP
The extensions to PCEP for FSPC include the definition of a new flag
in the RP object, a result path list/tree and a candidate node list
in a request message.
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7.1. RP Object Extension
The following flag is added into the RP Object:
The F bit is added in the flag bits field of the RP object to tell
the receiver of the message that the request/reply is for FSPC.
o F (FSPC bit - 1 bit):
0: This indicates that this is not PCReq/PCRep for FSPC.
1: This indicates that this is PCReq or PCRep message for FSPC.
The T bit is added in the flag bits field of the RP object to tell
the receiver of the message that the reply is for transferring a
request message to the domain containing the node with minimum cost
in the candidate list.
o T (Transfer request bit - 1 bit):
0: This indicates that this is not a PCRep
for transferring a request message.
1: This indicates that this is a PCRep message
for transferring a request message.
Setting Transfer request T-bit in a RP Object to one indicates that a
reply message containing the RP Object is for transferring a request
message to the domain containing the node with minimum cost in the
candidate list.
The IANA request is referenced in Section below (Request Parameter
Bit Flags) of this document.
This F bit with the N bit defined in RFC6006 can indicate whether the
request/reply is for FSPC of an MPLS TE P2MP LSP or an MPLS TE P2P
LSP.
o F = 1 and N = 1: This indicates that this is a PCReq/PCRep
message for FSPC of an MPLS TE P2MP LSP.
o F = 1 and N = 0: This indicates that this is a PCReq/PCRep
message for FSPC of an MPLS TE P2P LSP.
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7.2. PCE Object
The figure below illustrates a PCE IPv4 object body (Object-Type=1),
which comprises a PCE IPv4 address. The PCE IPv4 address object
indicates the IPv4 address of a PCE , with which a PCE session may be
established and to which a request message may be sent.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PCE IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The format of the PCE object body for IPv6 (Object-Type=2) is as
follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| PCE IPv6 address (16 bytes) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.3. Candidate Node List Object
The candidate-node-list-obj object contains a list of candidate
nodes. A new PCEP object class and type are requested for it. The
format of the candidate-node-list-obj object body is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// <candidate-node-list> //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following is the definition of the candidate node list.
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<candidate-node-list>::= <candidate-node>
[<candidate-node-list>]
<candidate-node>::= <ERO>
<candidate-attribute-list>
<candidate-attribute-list>::= [<attribute-list>]
[<PCE>]
[<Node-Flags>]
The ERO in a candidate node contain just the path segment of the last
link of the path, which is from the previous hop node of the tail end
node of the path to the tail end node. With this information, we can
graft the candidate node into the existing result path list or tree.
Simply speaking, a candidate node has the same or similar format of a
path defined in RFC 5440, but the ERO in the candidate node just
contain the tail end node of the path and its previous hop, and the
candidate node may contain two new objects PCE and node flags.
7.4. Node Flags Object
The Node Flags object is used to indicate the characteristics of the
node in a candidate node list in a request or reply message for FSPC.
The Node Flags object comprises a Reserved field, and a number of
Flags.
The format of the Node Flags object body is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|S|I|E|N| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where
o D = 1: The node is a destination node.
o S = 1: The node is a source node.
o I = 1: The node is an entry boundary node.
o E = 1: The node is an exit boundary node.
o T = 1: The node is on the result path tree.
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7.5. Request Message Extension
Below is the message format for a request message with the extension
of a result path list and a candidate node list:
<PCReq Message>::= <Common Header>
<request>
<request>::= <RP> <END-POINT-RRO-PAIR-LIST> [<OF>] [<LSPA>]
[<BANDWIDTH>] [<metric-list>] [<RRO>[<BANDWIDTH>]]
[<IRO>] [<LOAD-BALANCING>]
[<result-path-list>]
[<candidate-node-list-obj>]
where:
<result-path-list>::=<path>[<result-path-list>]
<path>::= <ERO><attribute-list>
<attribute-list>::=[<LSPA>] [<BANDWIDTH>] [<metric-list>]
[<IRO>]
<candidate-node-list-obj> contains a <candidate-node-list>
<candidate-node-list>::= <candidate-node>
[<candidate-node-list>]
<candidate-node>::= <ERO>
<candidate-attribute-list>
<candidate-attribute-list>::= [<attribute-list>]
[<PCE>]
[<Node-Flags>]
Figure 1: The Format for a Request Message
The definition for the result path list that may be added into a
request message is the same as that for the path list in a reply
message that is described in RFC5440.
7.6. Reply Message Extension
Below is the message format for a reply message with the extension of
a result path list and a candidate node list:
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<PCRep Message> ::= <Common Header>
<response>
<response> ::= <RP> [<END-POINT-PATH-PAIR-LIST>]
[<NO-PATH>] [<attribute-list>]
[<result-path-list>]
[<candidate-node-list-obj>]
where:
<candidate-node-list-obj> contains a <candidate-node-list>
If the path from the source to the destinations is not found yet and
there are still chances to find a path (i.e., the candidate list is
not empty), the reply message contains candidate-node-list-obj
consisting of the information of the candidate list, which is
encoded. In this case, the Transfer request T-bit in the RP Object
is set to one.
If the path from the source to the destination is found, the reply
message contains path-list comprising the information of the path.
8. Security Considerations
The mechanism described in this document does not raise any new
security issues for the PCEP protocols.
9. IANA Considerations
This section specifies requests for IANA allocation.
9.1. Request Parameter Bit Flags
A new RP Object Flag has been defined in this document. IANA is
requested to make the following allocation from the "PCEP RP Object
Flag Field" Sub-Registry:
Bit Description Reference
18 FSPC (F-bit) This I-D
19 Transfer Request (T-bit) This I-D
10. Acknowledgement
The author would like to appreciate Dhruv Dhody for his great
contributions and to thank Julien Meuric, Daniel King, Cyril
Margaria, Ramon Casellas, Olivier Dugeon and Oscar Gonzalez de Dios
for their valuable comments on this draft.
Chen Expires 14 July 2022 [Page 14]
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11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC6006] Zhao, Q., Ed., King, D., Ed., Verhaeghe, F., Takeda, T.,
Ali, Z., and J. Meuric, "Extensions to the Path
Computation Element Communication Protocol (PCEP) for
Point-to-Multipoint Traffic Engineering Label Switched
Paths", RFC 6006, DOI 10.17487/RFC6006, September 2010,
<https://www.rfc-editor.org/info/rfc6006>.
11.2. Informative References
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC5862] Yasukawa, S. and A. Farrel, "Path Computation Clients
(PCC) - Path Computation Element (PCE) Requirements for
Point-to-Multipoint MPLS-TE", RFC 5862,
DOI 10.17487/RFC5862, June 2010,
<https://www.rfc-editor.org/info/rfc5862>.
Author's Address
Huaimo Chen
Futurewei
Boston, MA,
United States of America
Email: Huaimo.chen@futurewei.com
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