PCE Working Group L. Han
Internet-Draft Y. Zhao
Intended status: Standards Track Y. Liu
Expires: 24 April 2025 China Mobile
21 October 2024
PCEP Extension for Fine Grain Optical Transport Network (fgOTN)
draft-han-pce-fgotn-pcep-extension-00
Abstract
This document introduces the PCEP extension used for computed fgOTN
path from the PCE to the PCC.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements on the PCEP computed path information . . . . . 2
3. PCEP Extention for fgOTN path set-up . . . . . . . . . . . . 3
4. Manageability Considerations . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . 4
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
As SDH phases out in operators’ networks, Fine Grain Optical
Transport Network (fgOTN) technology complementing the existing OTN
with an additional fgOTN path layer network is used as an alternative
to carry private line services. A new fine grain ODU layer network
has been defined in ITU-T to carry these signals across the OTN
networks, to provide flexible N*10Mbps bandwidth TDM-based transport
capabilities.
ITU-T has a series of recommendations for fgOTN (fine grain OTN ).
The fgOTN overview is defined in [ITU-T_G.709.20], fgOTN layer
architecture is defined in [ITU-T_G.872], fgOTN Interface and server
adaptation is defined in [ITU-T_G.709], fgOTN equipment is defined
in[ITU-T_G.798], fgOTN synchronization is defined in [ITU-T_G.8251],
fgOTN management requirements is defined in [ITU-T_G.874] and
protocol-neutral information model is defined in [ITU-T_G.875].
[RFC8779]provides the PCEP extensions required for GMPLS
applications, for example, for Optical Transport Networks (OTNs) and
Wavelength Switched Optical Networks (WSONs). Due to the new
features of fgOTN technology, PCEP needs to be extended. The
requirements were analyzed in
[I-D.draft-han-pce-path-computation-fg-transport].
2. Requirements on the PCEP computed path information
For each computed fgOTN path, the information carried by the PCEP
should at least include: 1) fgOTN path information 2) fgOTN path
protection type 3) Path role (working path/backup path) 4) fgOTN path
bandwidth 5) fgOTN path list: a) node identifier b) Path identifier
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3. PCEP Extention for fgOTN path set-up
The centralized computation model of PCE architecture seems to be
suitable for the fine-granularity transport network, while the PCEP
(PCE communication protocol) needs to be extended to meet the fine-
granularity transport requirements.
The protocol and signaling should support the application of fine-
granularity path set-up/update/removal and resource management.
The extention for fgOTN path set-up is suggested as follows:
+==============+========+=========================================+
| Attribute | Length | Value |
| | (bits) | |
+==============+========+=========================================+
| Connection | 96 | Composed of three tuples (Source Node |
| Identifier | | Identifier, Destination Node |
| (LSP Object) | | Identifier, Service Index, each 32 |
| | | bits) |
+--------------+--------+-----------------------------------------+
| Protection | 8 | Includes 1+1 Protection, 1+1, Path |
| Type (LSPA | | Protection, No Protection, etc. |
| Object's | | |
| Protection | | |
| Attributes) | | |
+--------------+--------+-----------------------------------------+
| Primary/ | 8 | Set to 1 to indicate working path, set |
| Backup Flag | | to 0 to indicate protection path |
| (LSPA | | |
| Object, | | |
| Protection | | |
| Attributes) | | |
+--------------+--------+-----------------------------------------+
| Small | 8 | Timeslot granularity, requires fgOTN's |
| timeslot | | timeslot granularity. Timeslot |
| granularity | | granularity is defined by YD/T |
| (Generalized | | 4856-2024 and ITU-T G.709.20 standards; |
| Bandwidth | | 0 – 10Mbps (fgOTN) |
| Object) | | |
+--------------+--------+-----------------------------------------+
| fgOTN | 16 | Integer, expressed in terms of the |
| Bandwidth | | number of time slots |
| (Generalized | | |
| Bandwidth | | |
| Object) | | |
+--------------+--------+-----------------------------------------+
| Routing | See | Destination node identifier, fgOTN's |
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| Information | Table2 | ingress/egress fgOTN channel number |
| (LIST) | | length is 10 bits Refer to RFC5440 for |
| | | RP object's B Flag bit to determine |
| | | simplex or duplex. For simplex |
| | | connections, routing information (LIST) |
| | | will generate unidirectional exchanges. |
| | | For duplex connections, routing |
| | | information for both ingress and egress |
| | | will generate bidirectional exchanges. |
+--------------+--------+-----------------------------------------+
Table 1: Service provisioning Initiate/Update message coding
format (from control system to signaling head node)
+==========================================+===============+
| Attribute | Length (bits) |
+==========================================+===============+
| Network Element Identifier | 32 |
+------------------------------------------+---------------+
| Ingress | 32 |
+------------------------------------------+---------------+
| Ingress ODU Service Layer Channel Number | 16 |
+------------------------------------------+---------------+
| Ingress fgOTN Channel Number | 16 |
+------------------------------------------+---------------+
| Egress | 32 |
+------------------------------------------+---------------+
| Egress ODU Service Layer Channel Number | 16 |
+------------------------------------------+---------------+
| Egress fgOTN Channel Number | 16 |
+------------------------------------------+---------------+
Table 2: Routing Information Instance
4. Manageability Considerations
<Add any manageability considerations>
5. Security Considerations
<Add any security considerations>
6. IANA Considerations
<Add any IANA considerations>
7. Normative References
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[I-D.draft-han-pce-path-computation-fg-transport]
Han, L., Zheng, H., Wang, M., and Y. Zhao, "Path
Computation and Control Extention Requirements for Fine-
Granularity Transport Network", Work in Progress,
Internet-Draft, draft-han-pce-path-computation-fg-
transport, March 2024,
<https://datatracker.ietf.org/doc/html/draft-han-pce-path-
computation-fg-transport>.
[ITU-T_G.709]
International Telecommunication Union, "Interfaces for the
optical transport network", ITU-T Recommendation G.709 ,
July 2024.
[ITU-T_G.709.20]
International Telecommunication Union, "Overview of fine
grain OTN", ITU-T Recommendation G.709.20 , April 2024.
[ITU-T_G.798]
International Telecommunication Union, "Characteristics of
optical transport network hierarchy equipment functional
blocks", ITU-T Recommendation G.798 , September 2023.
[ITU-T_G.8251]
International Telecommunication Union, "The control of
jitter and wander within the optical transport network
(OTN)", ITU-T Recommendation G.8251 , November 2022.
[ITU-T_G.872]
International Telecommunication Union, "Architecture of
the optical transport network", ITU-T Recommendation
G.872 , March 2024.
[ITU-T_G.874]
International Telecommunication Union, "Management aspects
of optical transport network elements", ITU-T
Recommendation G.874 , October 2020.
[ITU-T_G.875]
International Telecommunication Union, "Optical transport
network: Protocol-neutral management information model for
the network element view", ITU-T Recommendation G.875 ,
June 2020.
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[RFC8779] Margaria, C., Ed., Gonzalez de Dios, O., Ed., and F.
Zhang, Ed., "Path Computation Element Communication
Protocol (PCEP) Extensions for GMPLS", RFC 8779,
DOI 10.17487/RFC8779, July 2020,
<https://www.rfc-editor.org/info/rfc8779>.
Acknowledgments
Authors' Addresses
Liuyan Han
China Mobile
Email: hanliuyan@chinamobile.com
Yang Zhao
China Mobile
Email: zhaoyangyjy@chinamobile.com
Yucong Liu
China Mobile
Email: liuyucongyjy@chinamobile.com
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