Internet DRAFT - draft-xiong-pce-multilayer-lsp-association
draft-xiong-pce-multilayer-lsp-association
PCE WG Quan. Xiong
Internet-Draft Fangwei. Hu
Intended status: Standards Track Ran. Chen
Expires: April 25, 2019 ZTE Corporation
October 22, 2018
PCE Multi-layer LSP Association
draft-xiong-pce-multilayer-lsp-association-02
Abstract
The Path Computation Element Communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path
computations in response to Path Computation Clients (PCCs) requests.
[I-D.ietf-pce-association-group] proposed an association mechanism
for a set of LSPs.
This document proposes a set of extensions to PCEP to associate a
grouping of multi-layer LSPs. The extensions define a mechanism to
create associations between upper-layer LSP and related lower-layer
LSPs.
Status of This Memo
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This Internet-Draft will expire on April 25, 2019.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Operation Overview . . . . . . . . . . . . . . . . . . . 4
4. Extensions to the PCEP . . . . . . . . . . . . . . . . . . . 5
4.1. Association Type and Group . . . . . . . . . . . . . . . 5
4.2. MULTI-LAYER-ASSOCIATION TLV . . . . . . . . . . . . . . . 5
5. PCEP Procedure . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Multi-Layer LSPs Associations Creation . . . . . . . . . 6
5.2. Bandwidth Adjustment . . . . . . . . . . . . . . . . . . 6
5.3. TE Links Optimization . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7.1. Association Object Type . . . . . . . . . . . . . . . . . 7
7.2. LAYER-ASSOCIATION TLV . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Informative References . . . . . . . . . . . . . . . . . 8
9.2. Normative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
[RFC5440] describes the Path Computation Element Protocol (PCEP)
which is used between a Path Computation Element (PCE) and a Path
Computation Client (PCC) (or other PCE) to enable computation of
Multi-protocol Label Switching (MPLS) for Traffic Engineering Label
Switched Path (TE LSP). [I-D.ietf-pce-association-group] proposed an
association mechanism to create a grouping of LSPs in the context of
a PCE.
This document proposes a set of extensions to PCEP to associate a
grouping of multi-layer LSPs. The extensions define a mechanism to
create associations between upper-layer LSP and related lower-layer
LSPs.
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2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2.1. Terminology
The terminology is defined as [RFC5440]
,[I-D.ietf-pce-stateful-pce-app] and
[I-D.ietf-pce-association-group].
3. Overview
3.1. Motivation
In GMPLS/MPLS networks, service provider network is divided into
several service layers according to the requirements and customer
network is the upper layer with the lower layers as the Forwarding
Adjacency LSP (FA-LSP) as shown in Figure 1. The service connection
is established with the set up of multi-layer LSPs.
Initiate & Update LSP and related lower LSPs
|
|
V
+---+--+
+--------------+ PCE +---------------+
| +---+--+ |
| | |
| | |
| | |
+---+--+ +---+--+ +---+--+
| PCC1 +-----------+ PCC2 +-----------+ PCC3 +
+------+ LSP1-> +------+ LSP2-> +------+
| |
|<------ LSP3 ----->|
Figure 1 Usecase for multi-layer LSPs
As discussed in [I-D.ietf-pce-stateful-pce-app] , it consists of a
set of one or more TE LSPs in the lower layer which provides TE links
to the upper layer in Multi-Layer Networks (MLN). The requirement is
to control of the multi-layer LSPs and related TE links. The
establishment or teardown of a lower layer LSP needs to take into
consideration the state of existing LSPs or new LSP request in the
upper layer.
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As discussed in [I-D.ietf-pce-stateful-pce] , the stateful PCE MAY
determine to optimize the link and path based on the lower layer of
the LSP and its upper TE Link, and in the case of the failure of the
lower level LSP, it MAY update the upper network LSP path according
to the existing resources and the status of the LSP.
The stateful PCE provides the ability to update the LSP, in the
process of bandwidth adjustment, it MAY be necessary to adjust the
bandwidth of related lower layer LSPs, which provide the TE link for
the upper layer LSP. The association of multi-layer LSPs can reduce
the repeated operations and optimize the information interaction
between PCC and PCE.
In overlayer multi-domain scenario, the lower-layer LSPs in each
domain may be initiated by respective domain's PCE and stitched
together to an association group with an end-to-end LSP as its upper-
layer LSP.
In these cases, it is necessary to add multi-layer LSPs to an
association group.
3.2. Operation Overview
[I-D.ietf-pce-association-group] introduces a generic mechanism to
create a grouping of LSPs. This grouping can then be used to define
associations between sets of LSPs or between a set of LSPs and a set
of attributes.
In order to solve the problem of multi-layer LSP control in PCE
network, this document proposes the association if the multi-layer
LSPs. The upper LSP is associated with its related lower LSPs by
adding them to a multi-layer association group.
One new optional Association Object type is defined carried in the
Association object defined in [I-D.ietf-pce-association-group]. This
document proposes a new association type called "Layer Association
Type" and related TLV called "LAYER-ASSOCIATION TLV".
As defined in [I-D.ietf-pce-association-group], multi-layer LSPs
associations could be created dynamically or configured by the
operator when operator-configured association is needed.
The handling and policy of multi-layer LSPs Association is similar to
the generic association and some processing rules as shown in session
4.2.
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4. Extensions to the PCEP
4.1. Association Type and Group
[I-D.ietf-pce-association-group] introduces the ASSOCIATION object
and this document proposes a new Association type for multi-layer
LSPs association to associate multi-layer LSPs into one group for
further operation. An association ID will be used to identify the
group and a new Association Type is defined in this document, based
on the generic Association object :
Association type = TBD1 ("Multi-Layer Association Type") for Multi-
Layer Association Group (MLAG)
MLAG may carry optional TLVs including but not limited to :
MULTI-LAYER-ASSOCIATION-TLV: Used to identify the upper-layer LSP and
lower-layer LSP in multi-layer information, described in Section 4.2.
As [I-D.ietf-pce-association-group] specified, the capability
advertisement of the association types supported by a PCEP speaker is
performed by defining a ASSOC-Type-List TLV to be carried within an
OPEN object. The association type which defined in this document
should be added in the list and be advertised between the PCEP
speakers before the multi-layer association.
This Association-Type is operator-configured and created by the
operator manually on the PCEP peers. The LSP belonging to this
associations is conveyed via PCEP messages to the PCEP peer.
Operator-configured Association Range SHOULD NOT be set for this
association-type, and MUST be ignored, so that the full range of
association identifier can be utilized.
4.2. MULTI-LAYER-ASSOCIATION TLV
This document proposes LAYER-ASSOCIATION TLV for the association of
multi-layer LSPs. The TLV is optional. The format of the new
Association TLV is shown in Figure 4:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = TBD | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Layer Association Flags |H|L|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: The LAYER-ASSOCIATION TLV format
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The type of the TLV is [TBD] which indicates the LAYER ASSOCIATION
TLV. The fields in the format are:
Length:16bits,the length of the TLV.
Layer Association Flags-H:1bit, indicates LSP of the upper layer when
it is set.
Layer Association Flags-L:1bit, indicates LSP of the lower layer when
it is set.
5. PCEP Procedure
Once a group of multilayer LSPs is created, the upper layer LSP is
associated with its related lower layer LSPs. Association objects
can be carried in PCReq, PCRpt, PCUpd, or PCInit messages.
5.1. Multi-Layer LSPs Associations Creation
As defined in [I-D.ietf-pce-association-group], association groups
can be created by both PCC and PCE.
In stateless PCE, the association object with "Layer Association
type" is carried in PCReq message from PCC to PCE, indicating that
the LSP joins one existing multi-layer LSPs association group or
create a new one. If the LSP is belong to upper layer then set the
"H" bit in "LAYER-ASSOCIATION TLV", otherwise set the "L" bit when it
is lower layer LSP.
In stateful PCE, PCE MAY create a new association group or associate
a LSP to an existing association group carried in PCInit message
after the LSP delegation from PCC to the PCE as discussed in
[I-D.ietf-pce-pce-initiated-lsp]. In state synchronization process
between PCC and PCE, PCC also need to report the existing multi-layer
LSPs association groups to PCE. If the association group changes,
PCC needs to report the relevant group changes to PCE through the
PCRpt message.
5.2. Bandwidth Adjustment
The stateful PCE provides the ability to update the LSP, in the
process of bandwidth adjustment, for example, enlarge the bandwidth
of the upper layer LSP, it MUST be necessary to adjust the bandwidth
of related lower layer LSPs, which provide the TE link for it.
Once the multi-layer LSPs associated in a group, the PCE MAY send the
PCUpd message to the PCC with the association object to adjust the
upper layer LSP. Once receiving the request, PCC will search the
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relevant lower layer LSPs and adjust their bandwidth before the
adjustment of the upper layer LSP.
5.3. TE Links Optimization
The stateful PCE MAY determine to optimize the link and path based on
the lower layer of the LSP and its upper TE Link, and in the case of
the failure of the lower level LSP, it MAY update the upper network
LSP path and re-optimize resource usage across multi-layers.
When removing the upper layer LSP, PCC or PCE MAY release each of
lower layer LSPs which associated in a group and re-use the resources
for other upper layer LSP according to the existing resources and the
status of the LSP.
6. Security Considerations
TBD
7. IANA Considerations
7.1. Association Object Type
This document defines a new association type in Association object
which originally defined in [I-D.ietf-pce-association-group]. IANA
is requested to make allocations from the registry, as follows:
+--------+-------------------------+------------------+
| Value | Name | Reference |
+--------+-------------------------+------------------+
| TBD | Layer Association Type | [this document] |
+--------+-------------------------+------------------+
Table 1
7.2. LAYER-ASSOCIATION TLV
This document defines the following TLV in Association object which
originally defined in [I-D.ietf-pce-association-group]. IANA is
requested to make allocations from the registry, as follows:
+--------+-----------------------+------------------+
| Value | Name | Reference |
+--------+-----------------------+------------------+
| TBD | LAYER-ASSOCIATION TLV | [this document] |
+--------+-----------------------+------------------+
Table 2
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8. Acknowledgements
TBD.
9. References
9.1. Informative References
[I-D.ietf-pce-stateful-pce-app]
Zhang, X. and I. Minei, "Applicability of a Stateful Path
Computation Element (PCE)", draft-ietf-pce-stateful-pce-
app-08 (work in progress), October 2016.
9.2. Normative References
[I-D.ietf-pce-association-group]
Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Dhody, D., and Y. Tanaka, "PCEP Extensions for
Establishing Relationships Between Sets of LSPs", draft-
ietf-pce-association-group-06 (work in progress), June
2018.
[I-D.ietf-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-ietf-pce-pce-initiated-lsp-11 (work in
progress), October 2017.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-21 (work in progress), June 2017.
[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>.
[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>.
Authors' Addresses
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Quan Xiong
ZTE Corporation
No.6 Huashi Park Rd
Wuhan, Hubei 430223
China
Phone: +86 27 83531060
Email: xiong.quan@zte.com.cn
Fangwei Hu
ZTE Corporation
No.889 Bibo Rd
Shanghai 201203
China
Phone: +86 21 68896273
Email: hu.fangwei@zte.com.cn
Ran Chen
ZTE Corporation
No.50 Software Avenue,Yuhuatai District
Nanjing, Jiangsu Province 210012
China
Phone: +86 025 88014636
Email: chen.ran@zte.com.cn
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