Internet DRAFT - draft-ietf-ccamp-wson-signal-compatibility-ospf
draft-ietf-ccamp-wson-signal-compatibility-ospf
Network Working Group Y. Lee
Internet Draft Huawei
Intended status: Standards Track G. Bernstein
Expires: February 2016 Grotto Networking
August 28, 2015
GMPLS OSPF Enhancement for Signal and Network Element Compatibility
for Wavelength Switched Optical Networks
draft-ietf-ccamp-wson-signal-compatibility-ospf-17.txt
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Abstract
This document provides Generalized Multiprotocol Label Switching
(GMPLS) Open Shortest Path First (OSPF) routing enhancements to
support signal compatibility constraints associated with Wavelength-
Switched Optical network (WSON) elements. These routing enhancements
are applicable 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 Optical-Electronic-Optical
(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 [RFC2119].
Table of Contents
1. Introduction...................................................3
2. The Optical Node Property TLV..................................3
2.1. Resource Block Information................................5
2.2. Resource Accessibility....................................5
2.3. Resource Wavelength Constraints...........................5
2.4. Resource Block Pool State.................................5
2.5. Resource Block Shared Access Wavelength Availability......5
3. Interface Switching Capability Descriptor (ISCD) Format
Extensions........................................................5
3.1. Switching Capability Specific Information.................6
4. WSON Specific Scalability and Timeliness.......................7
5. Security Considerations........................................8
6. IANA Considerations............................................9
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6.1. Optical Node Property TLV.................................9
6.1.1. Optical Node Property Sub-TLV........................9
6.2. WSON-LSC Switching Type TLV..............................10
6.2.1. WSON-LSC SCSI Sub-TLVs..............................10
7. References....................................................11
7.1. Normative References.....................................11
7.2. Informative References...................................11
8. Authors' Addresses............................................12
1. Introduction
The documents [RFC6163, RFC7446, RFC7581] explain how to extend the
Wavelength Switched Optical Network (WSON) control plane to support
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 applicable 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.
Related to this document is [RFC7580] which provides GMPLS OSPF
routing enhancements to support the generic routing and label
assignment process that can be applicable to a wider range of
technologies beyond WSON.
2. The Optical Node Property TLV
[RFC3630] defines OSPF Traffic Engineering (TE) Link State
Advertisement (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
comprised of a set of optional sub-TLVs. There are no ordering
requirements for the sub-TLVs.
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When using the extensions defined in this document, at least one
Optical Node Property TLV MUST be advertised in each LSA. To allow
for fine granularity changes in topology, more than one Optical Node
Property TLV MAY be advertised in a single LSA. Implementations MUST
support receiving multiple Optical Node Property TLVs in an 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 [RFC7581].
The following sub-TLVs of the Optical Node Property TLV are defined:
Value Length Sub-TLV Type
TBA1 variable Resource Block Information
TBA2 variable Resource Accessibility
TBA3 variable Resource Wavelength Constraints
TBA4 variable Resource Block Pool State
TBA5 variable Resource Block Shared Access Wavelength
Availability
The detailed encodings of these sub-TLVs are found in [RFC7581] as
indicated in the table below.
Sub-TLV Type Section [RFC7581]
Resource Block Information 4.1
Resource Accessibility 3.1
Resource Wavelength Constraints 3.2
Resource Block Pool State 3.3
Resource Block Shared Access Wavelength Availability 3.4
All sub-TLVs defined here may occur at most once in any given
Optical Node TLV under one TE LSA. If more than one copy of the sub-
TLV is received in the same LSA, the redundant sub-TLV SHOULD be
ignored. In case where the same sub-TLV is advertised in different
TE LSA (which would take place only by a packaging error), then the
sub-TLV with the largest LSA ID (Sec 2.2 of RFC 3630) SHOULD be
picked. These restriction need not apply to future sub-TLVs.
Unrecognized sub-TLVs are ignored.
Among the sub-TLVs defined above, the Resource Block Pool State sub-
TLV and Resource Block Shared Access Wavelength Availability are
dynamic in nature while the rest are static. As such, they can be
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separated out from the rest and be advertised with multiple TE LSAs
per OSPF router, as described in [RFC3630] and [RFC5250].
2.1. Resource Block Information
As defined in [RFC7446], this sub-TLV is used to represent resource
signal constraints and processing capabilities of a node.
2.2. Resource 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.
2.3. Resource Wavelength Constraints
Resources, such as wavelength converters, etc., may have 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. The Resource Wavelength
Constraints sub-TLV describes these properties.
2.4. Resource Block Pool State
This sub-TLV describes the usage state of a resource that can be
encoded as either a list of 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.
2.5. Resource Block Shared Access Wavelength Availability
Resource 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.
3. Interface Switching Capability Descriptor (ISCD) Format Extensions
The ISCD describes switching capability of an interface [RFC4202].
This document defines a new Switching Capability value for WSON as
follows:
Value Type
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----- ----
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. Switching Capability Specific Information (SCSI)
The technology specific part of the WSON ISCD may include a variable
number of sub-TLVs called Bandwidth sub-TLVs. Two types of
Bandwidth sub-TLV are defined:
- Type 1 - Available Labels
- Type 2 - Shared Backup Labels
A SCSI may contain multiple Available Label sub-TLVs and multiple
Shared Backup Label sub-TLVs. The following figure shows the format
for a SCSI that contains these sub-TLVs. The order of the sub-TLVs
in the SCSI is arbitrary.
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 |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 2 (Shared backup) | Length |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Shared Backup Label Sub-TLV |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: SCSI format
Where the Available Label Sub-TLV and Shared Backup Label sub-TLV
are defined in [RFC7579]. In case where duplicated sub-TLVs are
advertised, the router/node will ignore the duplicated labels which
are identified by the Label format defined in [RFC6205].
The label format defined in [RFC6205] MUST be used when advertising
interfaces with a WSON-LSC type Switching Capability.
4. WSON Specific Scalability and Timeliness
This document has defined five sub-TLVs specific to WSON. The
examples given in [RFC7581] 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. A typical node configuration refers to a system
with several hundreds of channels with an OEO element in the node.
This would give optical node property TLV less than 350 bytes. In
addition, [RFC7581] provides mechanisms to compactly encode required
information elements. In a rare case where the TLV exceed the IP
MTU, IP fragmentation/reassembly can be used, which is an acceptable
method. For IPv6, a node may use the IPv6 Fragment header to
fragment the packet at the source and have it reassembled at the
destination(s).
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.
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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 computation 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 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 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.
In case where the new sub-TLVs or their attendant encodings are
malformed, the proper action SHOULD log the problem and MUST stop
sending the LSA in which to contain malformed TLVs or sub-TLVs.
Errors of this nature SHOULD be logged for the local operator.
Implementations MUST provide a rate limit on such logs, and that
rate limit SHOULD be configurable.
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].
As with [RFC4203], it specifies the contents of Opaque LSAs in
OSPFv2. As Opaque LSAs are not used for Shortest Path First (SPF)
computation or normal routing, the extensions specified here have no
direct effect on IP routing. Tampering with GMPLS TE LSAs may have
an effect on the underlying Transport. [RFC3630] notes that the
security mechanisms described in [RFC2328] apply to Opaque LSAs
carried in OSPFv2.
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For general security aspects relevant to Generalized Multiprotocol
Label Switching (GMPLS)-controlled networks, please refer to
[RFC5920].
6. IANA Considerations
6.1. Optical Node Property TLV
This document introduces a new Top Level Node TLV (Optical Node
Property TLV) under the OSPF TE LSA defined in [RFC3630].
IANA is asked to register a new TLV for "Optical Node Property". The
new TLV will be registered in the "Top Level Types in TE LSAs"
registry in "OSPF Traffic Engineering TLVs", located at
http://www.iana.org/assignments/ospf-traffic-eng-tlvs, as follows:
Value TLV Type Reference
6 (TBA6) Optical Node Property [This.ID]
6.1.1. Optical Node Property Sub-TLV
Additionally, a new IANA registry will be created for sub-TLVs of
the Optical Node Property TLV to create a new section named "Types
of sub-TLVs of Optical Node Property TLV (Value TBA)" in the "OSPF
Traffic Engineering TLVs" registry located at
http://www.iana.org/assignments/ospf-traffic-eng-tlvs/ospf-traffic-
eng-tlvs.xml, and allocate new sub-TLV Types and their Values for
these sub-TLVs defined under the Optical Node Property TLV as
follows:
Value Length Sub-TLV Type Reference
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0 Reserved
1 (TBA1) variable Resource Block Information [This.ID]
2 (TBA2) variable Resource Accessibility [This.ID]
3 (TBA3) variable Resource Wavelength
Constraints [This.ID]
4 (TBA4) variable Resource Block Pool State [This.ID]
5 (TBA5) variable Resource Block Shared
Access Wavelength Availability [This.ID]
6-65535 Unassigned
Types are to be assigned via Standards Action as defined in
[RFC5226].
6.2. WSON-LSC Switching Type TLV
IANA is asked to register a new switching type for "WSON-LSC
capable" in the Switching Types registry in "GMPLS Signaling
Parameters", located at http://www.iana.org/assignments/gmpls-sig-
parameters/, as follows:
Switching capability Description Reference
---------------------- -------------------------- ----------
151 (TBA7) WSON-LSC capable (WSON-LSC) [This.ID]
6.2.1. WSON-LSC SCSI Sub-TLVs
Additionally, a new IANA registry will be created for sub-TLVs of
the WSON-LSC SCSI sub-TLV to create a new section/sub-registry named
"Types for sub-TLVs of WSON-LSC SCSI (Switch Capability-Specific
Information)" section under the "OSPF Traffic Engineering TLVs"
registry, with the following sub-TLV types:
Value Sub-TLV Reference
0 Reserved
1 (TBA8) Available Labels [This.ID]
2 (TBA9) Shared Backup Labels [This.ID]
3-65535 Unassigned
Types are to be assigned via Standards Action as defined in
[RFC5226].
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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.
[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005.
[RFC6205] T. Otani, Ed. and D. Li, Ed., "Generalized Labels for
Lambda-Switch-Capable (LSC) Label Switching Routers", RFC
6205, March 2011.
[RFC7581] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information Encoding for Wavelength
Switched Optical Networks", RFC 7581, June 2015.
[RFC7579] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "General Network
Element Constraint Encoding for GMPLS Controlled
Networks", RFC 7579, June 2015.
[RFC7580] F. Zhang, Y. Lee, J. Han, G, Bernstein and Y. Xu, "OSPF-TE
Extensions for General Network Element Constraints", RFC
7580, June 2015.
7.2. Informative References
[RFC7446] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information Model for Wavelength
Switched Optical Networks", RFC 7446, February 2015.
[RFC4202] K. Kompella, Ed., and Y. Rekhter, Ed., "Routing Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, October 2005.
[RFC6163] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS and
PCE Control of Wavelength Switched Optical Networks", RFC
6163, April 2011.
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[RFC5250] Berger, L., et al., "The OSPF Opauqe LSA option", RFC
5250, July 2008.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5920] Luyuan Fang(Ed.), "Security Framework for MPLS and GMPLS N
Networks", RFC5920, July 2010.
8. Authors' Addresses
Young Lee (ed.)
Huawei Technologies
5340 Legacy Drive, Building 3
Plano, TX 75024
USA
Phone: (469)277-5838
Email: leeyoung@huawei.com
Greg M. Bernstein (ed.)
Grotto Networking
Fremont California, USA
Phone: (510) 573-2237
Email: gregb@grotto-networking.com
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