Network Working Group Pierre Peloso
Internet Draft Alcatel-Lucent
Intended status: Standard Track Julien Meuric
Expires: April 2011 France Telecom
Giovanni Martinelli
Cisco
October 25, 2010
OSPF-TE Extensions for WSON-specific Network Element Constraints
draft-peloso-ccamp-wson-ospf-oeo-02.txt
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Abstract
This document describes OSPF routing protocols extensions to support
blocking nodes and O-E-O pools in all-optical networks under the
control of Generalized MPLS (GMPLS).
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 [RFC2119].
Table of Contents
1. Introduction................................................2
2. Resource Block Attribute.....................................3
2.1. Pool ID................................................5
2.2. Block Shared Access Wavelength Availability.............5
2.3. Resource Element Information............................5
2.4. Relation with Node......................................5
3. Security Considerations......................................6
4. IANA Considerations.........................................6
4.1. Resource Block attributes...............................6
5. References..................................................6
6. Author's Addresses..........................................8
Intellectual Property Statement.................................8
Disclaimer of Validity.........................................9
1. Introduction
The goal of all-optical meshed networks consists in the transport of
optical circuit connections, with limited usage of Optical-
Electrical-Optical conversion through photonic nodes. The gain
brought by the use of fewer regenerators is balanced by the
constraint of maintaining the optical signal continuity between the
source and the destination nodes. In GMPLS controlled networks, the
induced signal continuity brings the technological challenge of
wavelength assignment using control plane protocols, which is
discussed in [WSON-Frame].
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The drawback of wavelength assignment computation in a single entity
is the need to gather and convey all relevant and up-to-date
information to this single entity. Whether the computing entity takes
the form of a PCE or the form of a Constrained-Shortest-Path-First
(C-SPF) engine in each node of the network, the IGP is supposed to do
the job of gathering this information.
This document defines extensions to the OSPF routing protocol based
on [WSON-Encode] to enhance the Traffic Engineering (TE) properties
of GMPLS TE which are defined in [RFC3630], [RFC4202], and [RFC4203].
The enhancements to the Traffic Engineering (TE) properties of GMPLS
TE links can be announced in OSPF TE LSAs. The TE LSA, which is an
opaque LSA with area flooding scope [RFC3630], has only one top-level
Type/Length/Value (TLV) triplet and has one or more nested sub-TLVs
for extensibility. The top-level TLV can take one of three values (1)
Router Address [RFC3630], (2) Link [RFC3630], (3) Node Attribute
[RFC5786]. In this document, we introduce a new top-level TLV
containing Resource Block Attribute (RBA).
[WSON-Encode] introduce the concept of RBA to include all information
that are specific to WSON nodes. This information may introduce some
additional constrains that needs to be considered to perform a
correct RWA. This document does not define any additional encoding
but maps information from [WSON-Info] and [WSON-Encode] on OSPF.
The detailed encoding of OSPF extensions are not defined in this
document. [WSON-Encode] provides encoding detail.
2. Resource Block Attribute
This draft defines a new top-TLV named "Resource Block Attribute"
TLV. It carries attributes related to a pool of Optical-Electric-
Optical regeneration resource, thus allowing route computation to
take into account available signal regenerators in the network.
Available OEO resource introduce different kind of constrains. One is
the signal compatibility as defined in [WSON-Signal]. Another
constrain comes from WSON node topologies (for technology reasons or
cost of resources). This draft mainly refers to the latter.
Multiple O-E-O resources are logically gathered in a pool when they
share a common transmission media before (and after) entering
(exiting) the actual switching matrix of the node. A common
transmission media is characterized by the sharing of at least a
short section of fiber: hence an amplifier or a wavelength selective
switch does also correspond to a common transmission media.
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When several regenerators' pools are available on a node, several
"Resource Block Attribute" will be used (one for each pool). As a
matter of fact, the split into blocks of the O-E-O resources comes
from the architectural structure of the node. This Node Attribute TLV
contains two or more sub-TLVs.
The resource block attributes related to OEO pools in WSON nodes
include Block ID, lists of available wavelengths on the ingress and
egress side of the pool, and the features of the resources in the
block. These pieces of information are described in this document and
refer to . The Resource Block Attribute would also include some sub-
TLVs identical to sub-TLVs of the TE-link top-TLV: TE-metric
[rfc3630], Administrative Group [rfc3630], Link Local/Remote
Identifiers [rfc4203], Shared-Risk Link Group [rfc4203].
The following new sub-TLVs are added to the "Resource Block
Attribute" TLV. Detailed description for newly defined sub-TLVs is
provided at the end of the section.
Sub-TLV Type Length Name
TBD 4 Bytes Block ID
TBD variable Block Shared Access Wavelength
Availability
TBD fixed Resource Element Information
In "Resource Block Attribute", the sub-TLV "Block Shared Access
Wavelength Availability" and "Resource Block Information" are
mandatory, the other sub-TLV listed above is optional.
The following sub-TLVs to the "Resource Block Attribute" TLV are
identical to the ones defined respectively in [RFC3630] and
[RFC4203], and being defined for the TE-link top-TLV. Detailed
description for newly defined sub-TLV is provided at the end of the
section.
Sub-TLV Type Length Name
TBD 4 Bytes TE-metric [alike RFC3630]
TBD 4 Bytes Administrative Group [alike RFC3630]
TBD 8 Bytes Link Local/Remote Identifiers [alike
RFC4203]
TBD variable Shared Risk Link Group [alike RFC4203]
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In "Resource Block Attribute", the sub-TLV "Link Local/Remote
Identifiers" is mandatory as it is needed to ensure the consistency
with the Node Information described in [Gen-OSPF] and [Gen-Encode].
The other sub-TLVs listed above are optional.
2.1. Pool ID
This optional sub-TLV can be used to provide an identifier to the
regenerator pool.
2.2. Block Shared Access Wavelength Availability
This block includes information from [WSON-Encode] section 4.4 "Block
Shared Access Wavelength Availability". It is used to describe the
wavelengths available on the shared fibers (ingress and egress sides)
of the pool.
At every RWA process the OEO pool may or may-not be used. The status
of the wavelength availability will change. The information is fairly
dynamic.
2.3. Resource Element Information
This sub-TLV advertises information that describes the features of
the resource elements inside the resource block itself. The features
are the accepted bit-rates, modulation format, FEC formats, etc...
Actually this sub-TLV is replicated in a list of such sub-TLVs in
order to depict all the resource elements available in the pool. The
description of the encoding of this sub-TLV is available in [WSON-
encode] section 5 (Hence needs a slight adaptation of TLV described
in 5.1: Resource Block Information).
The features of a given element are fairly static as they refer to
the characteristics of the device, which mean that the content of a
given sub-TLV is static. On the other hand, the elements composing
the list are subject to change, when a device is used, its
corresponding sub-TLV will disappear from the list.
2.4. Relation with Node
Accessing resource block is also subject to switching constraints.
These switching constraints can be both spatial and spectral.
In order to convey this information, the Connectivity Matrix sub-TLV
shall depict the ports of the O-E-O pool, and referring their Link
Local/Remote Identifiers sub-TLV as described in section 2.
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Hence the number of ports described by the connectivity matrix is:
# Ingress ports (CM): # incoming links (Node) + # O-E-O pools
# Egress ports (CM): # outgoing links (Node) + # O-E-O pools
3. Security Considerations
This document does not introduce any further security issues other
than those discussed in [RFC 3630], [RFC 4203].
4. IANA Considerations
[RFC3630] says that the top level Types in a TE LSA and Types for
sub-TLVs for each top level Types must be assigned by Expert Review,
and must be registered with IANA.
IANA is requested to allocate new Types for the sub-TLVs as defined
in Sections 2, 3, 3.1, 3.2 and 3.3 as follows:
4.1. Resource Block attributes
This document introduces the "O-E-O Pool Attribute" top-TLV, value
TBD with the following sub-TLVs:
Type Name
TBD Pool ID
TBD Block Shared Access Wavelength Availability
TBD Resource Element Information
TBD TE-metric [alike RFC3630]
TBD Administrative Group [alike RFC3630]
TBD Link Local/Remote Identifiers [alike RFC4203]
TBD Shared Risk Link Group [alike RFC4203]
5. References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471, January 2003.
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[RFC3630] Katz, D., Kompella, K., and Yeung, D., "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, September 2003.
[RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing Extensions
in Support of Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 4202, October 2005
[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC
4203, October 2005.
[RFC3945] E. Mannie, Ed., "Generalized Multi-Protocol Label Switching
(GMPLS) Architecture", RFC 3945, October 2004.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC5786] R. Aggarwal and K. Kompella, "Advertising a Router's Local
Addresses in OSPF TE Extensions", RFC 5786, March 2010.
[WSON-Frame] G. Bernstein, Y. Lee, W. Imajuku, "Framework for GMPLS
and PCE Control of Wavelength Switched Optical Networks", work in
progress: draft-ietf-ccamp-rwa-wson-framework-07.txt, October 2010.
[RWA-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information Model for Wavelength Switched
Optical Networks", work in progress: draft-ietf-ccamp-rwa-info-
06.txt, October 2010.
[Gen-Encode] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "General
Network Element Constraint Encoding for GMPLS Controlled Networks",
work in progress: draft-ietf-ccamp-general-ext-encode-00.txt.
[WSON-Encode] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information Encoding for Wavelength Switched
Optical Networks", work in progress: draft-ietf-ccamp-rwa-wson-
encode-06.txt, October 2010.
[Gen-OSPF] F. Zhang, Y. Lee, J. Han, G. Bernstein, " OSPF-TE
Extensions for General Network Element Constraints", work in
progress: draft-zhang-ccamp-general-constraints-ospf-ext-00.txt,
September 2010.
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6. Author's Addresses
Pierre Peloso
Alcatel-Lucent
Rte de Villejust
91620 Nozay, France
Phone: +33 130 702 662
Email: pierre.peloso@alcatel-lucent.com
Julien Meuric
France Telecom
2, av Pierre Marzin
22307 Lannion Cedex, France
Phone: +33 296 052 828
Email: julien.meuric@orange-ftgroup.com
Giovanni Martinelli
Cisco
Via Philips 12
20052 Monza, Italy
Phone: +39 039 2092044
Email: giomarti@cisco.com
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