GMPLS OSPF Enhancement for Signal and Network Element Compatibility for Wavelength Switched Optical Networks
draft-ietf-ccamp-wson-signal-compatibility-ospf-10
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 7688.
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|
|---|---|---|---|
| Authors | Young Lee , Greg M. Bernstein | ||
| Last updated | 2012-08-08 | ||
| Replaces | draft-lee-ccamp-wson-signal-compatibility-ospf | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-ccamp-wson-signal-compatibility-ospf-10
Network Working Group Y. Lee
Internet Draft Huawei
Intended status: Standards Track G. Bernstein
Expires: February 2013 Grotto Networking
August 8, 2012
GMPLS OSPF Enhancement for Signal and Network Element Compatibility
for Wavelength Switched Optical Networks
draft-ietf-ccamp-wson-signal-compatibility-ospf-10.txt
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Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Abstract
This document provides GMPLS OSPF routing enhancements to support
signal compatibility constraints associated with WSON network
elements. These routing enhancements are required in common optical
or hybrid electro-optical networks where not all of the optical
signals in the network are compatible with all network elements
participating in the network.
This compatibility constraint model is applicable to common optical
or hybrid electro optical systems such as OEO switches,
regenerators, and wavelength converters since such systems can be
limited to processing only certain types of WSON signals.
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...................................................3
1.1. Revision History..........................................3
2. The Optical Node Property TLV..................................4
2.1. Sub-TLV Details...........................................5
2.1.1. Resource Pool Accessibility..........................6
2.1.2. Resource Block Wavelength Constraints................6
2.1.3. Resource Pool State..................................6
2.1.4. Block Shared Access Wavelength Availability..........6
3. ISCD format extensions.........................................7
3.1. Switch Capability Specific Information....................7
4. WSON Specific Scalability and Timeliness.......................8
5. Security Considerations........................................9
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6. IANA Considerations............................................9
7. References....................................................11
7.1. Normative References.....................................11
7.2. Informative References...................................11
8. Authors and Contributors......................................12
Authors' Addresses...............................................12
Intellectual Property Statement..................................13
Disclaimer of Validity...........................................13
1. Introduction
The documents [RFC6163, WSON-Info, WSON-Encode] explain how to
extend the wavelength switched optical network (WSON) control plane
to allow both multiple WSON signal types and common hybrid electro
optical systems as well hybrid systems containing optical switching
and electro-optical resources. In WSON, not all of the optical
signals in the network are compatible with all network elements
participating in the network. Therefore, signal compatibility is an
important constraint in path computation in a WSON.
This document provides GMPLS OSPF routing enhancements to support
signal compatibility constraints associated with general WSON
network elements. These routing enhancements are required in common
optical or hybrid electro-optical networks where not all of the
optical signals in the network are compatible with all network
elements participating in the network.
This compatibility constraint model is applicable to common optical
or hybrid electro optical systems such as OEO switches,
regenerators, and wavelength converters since such systems can be
limited to processing only certain types of WSON signals.
1.1. Revision History
From 00 to 01: The details of the encodings for compatibility moved
from this document to [WSON-Encode].
From 01 to 02: Editorial changes.
From 02 to 03: Add a new Top Level Node TLV, Optical Node Property
TLV to carry WSON specific node information.
From 03 to 04: Add a new sub-TLV, Block Shared Access Wavelength
Availability TLV to be consistent with [WSON-Encode] and editorial
changes.
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From 04 to 05: Add a new section that discusses OSPF scalability and
timeliness and editorial changes.
From 05 to 06: Change the title of the draft to "GMPLS OSPF
Enhancement" from "OSPF Enhancement" to make sure the changes apply
to the GMPLS OSPF rather than the base OSPF. Add specific OSPF
procedures on how sub-TLVs are packaged per [RFC3630] and editorial
changes.
From 06 to 07: Add clarifying texts on how to sub-divide the Optical
Node TLV in case it exceeds the IP MTU fragmentation limit. Delete
Section 3.2. to avoid multiple rules so as to avoid confusion.
From 07 to 08: Clean some old texts in Section 3. Align with [WSON-
Encode] on the modulation and FEC type.
From 08 to 09: Added ISCD extensions for available labels and shared
backup labels.
From 09 to 10: Revised for OIC changes consistent with encoding
document.
2. The Optical Node Property TLV
[RFC3630] defines OSPF TE LSA using an opaque LSA. This document
adds a new top level TLV for use in the OSPF TE LSA: the Optical
Node Property TLV. The Optical Node property TLV describes a single
node. It is constructed of a set of sub-TLVs. There are no ordering
requirements for the sub-TLVs. Only one Optical Node TLV shall be
advertised in each LSA.
The Optical Node Property TLV contains all WSON-specific node
properties and signal compatibility constraints. The detailed
encodings of these properties are defined in [WSON-Encode].
The following sub-TLVs of the Optical Node Property TLV are defined:
Value Length Sub-TLV Type
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TBA variable Resource Block Information
TBA variable Resource Pool Accessibility
TBA variable Resource Block Wavelength Constraints
TBA variable Resource Pool State
TBA variable Block Shared Access Wavelength Availability
The detail encodings of these sub-TLVs are found in [WSON-Encode] as
indicated in the table below.
Sub-TLV Type Section [WSON-Encode]
Resource Block Information 5.1
Resource Pool Accessibility 4.1
Resource Block Wavelength Constraints 4.2
Resource Pool State 4.3
Block Shared Access Wavelength Availability 4.4
All sub-TLVs defined here may occur at most once in any given
Optical Node TLV. "At most once" means that if there is sub-TLV
related information, it should be always included. These
restrictions need not apply to future sub-TLVs. Unrecognized sub-
TLVs are ignored.
2.1. Sub-TLV Details
Among the sub-TLVs defined above, the Resource Pool State sub-TLV
and Block Shared Access Wavelength Availability are dynamic in
nature while the rest are static. As such, they can be separated out
from the rest and be advertised with multiple TE LSAs per OSPF
router, as described in [RFC3630] and [RFC5250]. Resource Block
Information
Resource Block Information sub-TLVs are used to convey relatively
static information about individual resource blocks including the
resource block properties and the number of resources in a block.
There are five nested sub-TLVs defined in the Resource Block
Information sub-TLV.
Value Length Sub-TLV Type
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TBA variable Optical Interface Class List
TBA variable Input Client Signal List
TBA variable Processing Capability List
The detail encodings of these sub-TLVs are found in [WSON-Encode] as
indicated in the table below.
Name Section [WSON-Encode]
Optical Interface Class List 5.2
Input Client Signal List 5.3
Processing Capability List 5.4
2.1.1. Resource Pool Accessibility
This sub-TLV describes the structure of the resource pool in
relation to the switching device. In particular it indicates the
ability of an ingress port to reach a resource block and of a
resource block to reach a particular egress port.
2.1.2. Resource Block Wavelength Constraints
Resources, such as wavelength converters, etc., may have a limited
input or output wavelength ranges. Additionally, due to the
structure of the optical system not all wavelengths can necessarily
reach or leave all the resources. Resource Block Wavelength
Constraints sub-TLV describe these properties.
2.1.3. Resource Pool State
This sub-TLV describes the usage state of a resource that can be
encoded as either a list of 16 bit integer values or a bit map
indicating whether a single resource is available or in use. This
information can be relatively dynamic, i.e., can change when a
connection is established or torn down.
2.1.4. Block Shared Access Wavelength Availability
Resources blocks may be accessed via a shared fiber. If this is the
case then wavelength availability on these shared fibers is needed
to understand resource availability.
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3. ISCD format extensions
The Interface Switching Capability Descriptor describes switching
capability of an interface [RFC 4202]. This document defines a new
Switching Capability value for WSON as follows:
Value Type
----- ----
151 (TBA by IANA) WSON-LSC capable (WSON-LSC)
Switching Capability and Encoding values MUST be used as follows:
Switching Capability = WSON-LSC
Encoding Type = Lambda [as defined in RFC3471]
When Switching Capability and Encoding fields are set to values as
stated above, the Interface Switching Capability Descriptor MUST be
interpreted as in RFC4203 with the optional inclusion of one or more
Switching Capability Specific Information sub-TLVs.
3.1. Switch Capability Specific Information
The technology specific part of the WSON ISCD may include a variable
number of sub-TLVs called Bandwidth sub-TLVs. Two types of
Bandwidth TLV are defined (TBA by IANA):
- Type 1 - Available Labels
- Type 2 - Shared Backup Labels
The format of the SCSI MUST be as depicted in the following figure:
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 = 1 (Available) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Available Label Sub-TLV |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 2 (Shared backup) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Shared Backup Label Sub-TLV |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: SCSI format
Where the Available Label Sub-TLV and Shared Backup Label sub-TLV
are defined in [Gen-Encode].
4. WSON Specific Scalability and Timeliness
This document has defined five sub-TLVs specific to WSON. The
examples given in [WSON-Encode] show that very large systems, in
terms of channel count, ports, or resources, can be very efficiently
encoded.
There has been concern expressed that some possible systems may
produce LSAs that exceed the IP Maximum Transmission Unit (MTU). In
a typical node configuration, the optical node property TLV will not
exceed the IP MTU. In a rare case where the TLV exceed the IP MTU,
IP fragmentation/reassembly can be used, which is an acceptable
method.
If the size of this LSA is greater than the MTU, then these sub-TLVs
can be packed into separate LSAs. From the point of view of path
computation, the presence of the Resource Block Information sub-TLV
indicates that resources exist in the system and may have signal
compatibility or other constraints. The other four sub-TLVs indicate
constraints on access to, and availability of those resources.
Hence the "synchronization" procedure from a path computation point
of view is quite simple. Until a Resource Block Information sub-TLV
is received for a system path cannot make use of the other four sub-
TLVs since it does not know the nature of the resources, e.g., are
the resources wavelength converters, regenerators, or something
else. Once this sub-TLV is received path computation can proceed
with whatever of the additional types of sub-TLVs it may have
received (there use is dependent upon the system type). If path
computation proceeds with out of date or missing information from
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these sub-TLVs then there is the possibility of either (a) path
computation computing a path that does not exist in the network, (b)
path computation failing to find a path through the network that
actually exists. Both situations are currently encountered with
GMPLS, i.e., out of date information on constraints or resource
availability.
Note that the connection establishment mechanism (signaling or
management) is ultimately responsible for the establishment of the
connection, and this implies that such mechanisms must insure signal
compatibility.
5. Security Considerations
This document does not introduce any further security issues other
than those discussed in [RFC3630], [RFC4203].
6. IANA Considerations
This document introduces a new Top Level Node TLV (Optical Node
Property TLV) under the OSPF TE LSA defined in [RFC3630].
Value TLV Type
TBA Optical Node Property
IANA is to allocate a new TLV Type and its Value for this Top Level
Node TLV.
This document also introduces the following sub-TLVs associated with
the Optical Node Property TLV as defined in Section 2.1 as follows:
Value Length Sub-TLV Type
TBA variable Resource Block Information
TBA variable Resource Pool Accessibility
TBA variable Resource Block Wavelength Constraints
TBA variable Resource Pool State
TBA variable Block Shared Access Wavelength Availability
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IANA is to allocate new sub-TLV Types and their Values for these
sub-TLVs defined under the Optical Node Property TLV.
There are five nested sub-TLVs defined in the Resource Block
Information sub-TLV as follows:
Value Length Sub-TLV Type
TBA variable Optical Interface Class List
TBA variable Input Client Signal List
TBA variable Processing Capability List
IANA is to allocate new Sub-TLV Types and their Values for these
Sub-TLVs defined under the Resource Block Information Sub-TLV.
Upon approval of this document, IANA will make the assignment of a
new Switching Capability value for the existing ISCD located at http:
//www.iana.org/assignments/ospf-traffic-eng-tlvs/ospf-traffic-eng-
tlvs.xml:
15 Interface Switching Capability Descriptor [RFC4203]
Switching capability Description Reference
---------------------- -------------------------- ----------
151 (suggested) WSON-LSC capable (WSON-LSC) [This.I-D]
This document defines the following sub-TLVs of the ISCD TLV:
Value Sub-TLV
----- -------------------------------------------------
1 Available Labels
2 Shared Backup Labels
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7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3630] Katz, D., Kompella, K., and Yeung, D., "Traffic
Engineering (TE) Extensions to OSPF Version 2", RFC
3630, September 2003.
[G.694.1] ITU-T Recommendation G.694.1, "Spectral grids for WDM
applications: DWDM frequency grid", June, 2002.
[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005.
[WSON-Encode] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information Encoding for Wavelength
Switched Optical Networks", draft-ietf-ccamp-rwa-wson-
encode, work in progress.
[Gen-Encode] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "General
Network Element Constraint Encoding for GMPLS Controlled
Networks", draft-ietf-ccamp-general-constraint-encode,
work in progress.
7.2. Informative References
[WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information Model for Wavelength
Switched Optical Networks", draft-ietf-ccamp-rwa-info,
work in progress.
[RFC6250] T. Otani, Ed., D. Li, Ed., "Generalized Labels for G.694
Lambda-Switching Capable Label Switching Routers", RFC
6250, March 2011.
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[RFC6163] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS
and PCE Control of Wavelength Switched Optical Networks",
RFC 6163, April 2011.
[RFC5250] Berger, L., et al., "The OSPF Opauqe LSA option", RFC
5250, July 2008.
8. Authors and Contributors
Authors' Addresses
Young Lee (ed.)
Huawei Technologies
1700 Alma Drive, Suite 100
Plano, TX 75075
USA
Phone: (972) 509-5599 (x2240)
Email: ylee@huawei.com
Greg M. Bernstein (ed.)
Grotto Networking
Fremont California, USA
Phone: (510) 573-2237
Email: gregb@grotto-networking.com
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