Internet DRAFT - draft-zhang-ccamp-flexible-grid-rsvp-te-ext
draft-zhang-ccamp-flexible-grid-rsvp-te-ext
Network Working Group Fatai Zhang
Internet-Draft Xian Zhang
Intended status: Standards Track Huawei
Adrian Farrel
Old Dog Consulting
Oscar Gonzalez de Dios
Telefonica
D. Ceccarelli
Ericsson
Expires: August 14, 2014 February 14, 2014
RSVP-TE Signaling Extensions in support of Flexible Grid
draft-zhang-ccamp-flexible-grid-rsvp-te-ext-04.txt
Abstract
This memo describes the extensions to RSVP-TE signaling to support
Label Switched Paths in a GMPLS-controlled network that includes
devices using the flexible optical grid.
Status of this Memo
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This Internet-Draft will expire on August 12, 2014.
Copyright Notice
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Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction ................................................ 2
2. Terminology ................................................. 3
2.1. Conventions used in this document .......................3
3. Requirements for Flexible Grid Signaling .....................3
3.1. Slot Width ............................................. 4
3.2. Frequency Slot ......................................... 4
4. Protocol Extensions ......................................... 5
4.1. Traffic Parameters...................................... 5
4.1.1. Applicability to Fixed Grid Networks ...............6
4.2. Generalized Label....................................... 6
4.3. Signaling Procedures.................................... 7
5. IANA Considerations ......................................... 7
5.1. RSVP Objects Class Types................................ 7
6. Manageability Considerations................................. 8
7. Implementation Status........................................ 8
7.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)8
8. Acknowledgments ............................................ 10
9. Security Considerations..................................... 10
10. References ................................................ 10
10.1. Normative References.................................. 10
10.2. Informative References................................ 10
11. Contributors' Address...................................... 11
12. Authors' Addresses .........................................12
1. Introduction
[G.694.1] defines the Dense Wavelength Division Multiplexing (DWDM)
frequency grids for Wavelength Division Multiplexing (WDM)
applications. A frequency grid is a reference set of frequencies
used to denote allowed nominal central frequencies that may be used
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for defining applications that utilize WDM transmission. The channel
spacing is the frequency spacing between two allowed nominal central
frequencies. All of the wavelengths on a fiber use different central
frequencies and occupy a designated range of frequency.
Fixed grid channel spacing is selected from 12.5 GHz, 25 GHz, 50 GHz,
100 GHz and integer multiples of 100 GHz. But [G.694.1] also defines
''flexible grids'', known as ''flexi-grid''. The terms ''frequency slot''
(i.e., the frequency range allocated to a specific channel and
unavailable to other channels within a flexible grid) and ''slot
width'' (i.e., the full width of a frequency slot in a flexible grid)
are introduced in [G.694.1] to define a flexible grid.
[FLEX-FWK] defines a framework and the associated control plane
requirements for the GMPLS based control of flexi-grid DWDM networks.
[RFC6163] provides a framework for GMPLS and Path Computation
Element (PCE) control of Wavelength Switched Optical Networks
(WSONs), and [WSON-SIG] describes the requirements and protocol
extensions for signaling to set up Label Switched Paths (LSPs) in
WSONs.
This document describes the additional requirements and protocol
extensions for RSVP-TE signaling to set up LSPs in networks that
support the flexi-grid.
2. Terminology
For terminology related to flexi-grid, please refer to [FLEX-FWK]
and [G.694.1].
2.1. 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].
3. Requirements for Flexible Grid Signaling
The architecture for establishing LSPs in a flexi-grid network is
described in [FLEX-FWK].
An optical spectrum LSP occupies a specific frequency slot, i.e., a
range of frequencies. The process of computing a route and the
allocation of a frequency slot is referred to as RSA (Routing and
Spectrum Assignment). [FLEX-FWK] describes three architectural
approaches to RSA: combined RSA, separated RSA, and distributed SA.
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The first two approaches are referred to as ''centralized SA'' because
both routing and spectrum (frequency slot) assignment are performed
by a centralized entity before the signaling procedure.
In the case of centralized SA the assigned frequency slot is
specified in the RSVP-TE Path message during LSP setup. In the case
of distributed SA, the slot width of the flexi-grid LSP is specified
in the Path message, allowing the network elements to select the
frequency slot to be used when they process the RSVP-TE messages.
If the capability to switch or convert the whole optical spectrum
allocated to an optical spectrum LSP is not available at some nodes
along the path of the LSP, the LSP is subject to the Optical
''Spectrum Continuity Constraint'' as described in [FLEX-FWK].
The remainder of this section states the additional requirements for
signaling in a flexi-grid network.
3.1. Slot Width
The slot width is an end-to-end parameter representing how much
frequency resource is requested for a flexi-grid LSP. It is the
equivalent of optical bandwidth, although the amount of bandwidth
associated with a slot width will depend on the signal encoding.
Different LSPs may request different amounts of frequency resource
in flexible grid networks, so the slot width needs to be carried in
the signaling message during LSP establishment. This enables the
nodes along the LSP to know how much frequency resource has been
requested (in a Path message) and has been allocated (by a Resv
message) for the LSP.
3.2. Frequency Slot
The frequency slot information identifies which part of the
frequency spectrum is allocated on each link for an LSP in a flexi-
grid network.
This information is required in a Resv message to indicate, hop-by-
hop, the central frequency of the allocated resource. In combination
with the slot width indicated in a Resv message (see Section 3.1)
the central frequency carried in a Resv message identifies the
resources reserved for the LSP (known as the frequency slot).
The frequency slot can be represented by the two parameters as
follows:
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Frequency slot = [(central frequency) - (slot width)/2] ~
[(central frequency) + (slot width)/2]
As is common with other resource identifiers (i.e., labels) in GMPLS
signaling, it must be possible for the head-end LSP when sending a
Path message to suggest or require the central frequency to be used
for the LSP. Furthermore, for bidirectional LSPs, the Path message
must be able to specify the central frequency to be used for reverse
direction traffic.
As described in [G.694.1], the allowed frequency slots for the
flexible DWDM grid have a nominal central frequency (in THz) defined
by:
193.1 + n * 0.00625
where n is zero or a positive or negative integer.
The slot width (in GHz) is defined as:
12.5 * m
where m is a positive integer.
It is possible that implementing a subset of the possible slot
widths and central frequencies are supported. For example, an
implementation could built where the nominal central frequency
granularity is 12.5 GHz (by only requiring values of n that are even)
and that only supports slot widths as a multiple of 25 GHz (by only
allowing values of m that are even).
Further details can be found in [FLEX-FWK].
4. Protocol Extensions
This section defines the extensions to RSVP-TE signaling for GMPLS
[RFC3473] to support flexible grid networks.
4.1. Traffic Parameters
In RSVP-TE, the SENDER_TSPEC object in the Path message indicates
the requested resource reservation. The FLOWSPEC object in the Resv
message indicates the actual resource reservation.
As described in Section 3.1, the slot width represents how much
frequency resource is requested for a flexi-grid LSP. That is, it
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describes the end-to-end traffic profile of the LSP. Therefore, the
traffic parameters for a flexi-grid LSP encode the slot width.
This document defines new C-Types for the SENDER_TSPEC and FLOWSPEC
objects to carry Spectrum Switched Optical Network (SSON) traffic
parameters:
SSON SENDER_TSPEC: Class = 12, C-Type = TBD1.
SSON FLOWSPEC: Class = 9, C-Type = TBD2.
The SSON traffic parameters carried in both objects have the same
format as shown in Figure 1.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| m | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The SSON Traffic Parameters
m (16 bits): the slot width is specified by m*12.5 GHz.
The Reserved bits MUST be set to zero and ignored upon receipt.
4.1.1. Applicability to Fixed Grid Networks
Note that the slot width (i.e., traffic parameters) of a fixed grid
defined in [G.694.1] can also be specified by using the SSON traffic
parameters. The fixed grid channel spacings (12.5 GHz, 25 GHz, 50
GHz, 100 GHz and integer multiples of 100 GHz) are also the
multiples of 12.5 GHz, so the m parameter can be used to represent
these slot widths.
Therefore, it is possible to consider using the new traffic
parameter object types in common signaling messages for flexi-grid
and legacy DWDM networks.
4.2. Generalized Label
In the case of a flexible grid network, the labels that have been
requested or allocated as signaled in the RSVP-TE objects are
encoded as described in [FLEX-LBL]. This new label encoding can
appear in any RSVP-TE object or sub-object that can carry a label.
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As noted in Section 4.2 of [FLEX-LBL], the m parameter forms part of
the label as well as part of the traffic parameters.
4.3. Signaling Procedures
There are no differences between the signaling procedure described
for LSP control in [FLEX-FWK] and those required for use in a fixed-
grid network [WSON-SIG]. Obviously, the TSpec, FlowSpec, and label
formats described in Section 3 are used. The signaling procedures
for distributed SA and centralized SA can be applied.
5. IANA Considerations
5.1. RSVP Objects Class Types
This document introduces two new Class Types for existing RSVP
objects. IANA is requested to make allocations from the "Resource
ReSerVation Protocol (RSVP) Parameters" registry using the "Class
Names, Class Numbers, and Class Types" sub-registry.
Class Number Class Name Reference
------------ ----------------------- ---------
9 FLOWSPEC [RFC2205]
Class Type (C-Type):
(TBD2) SSON FLOWSPEC [This.I-D]
Class Number Class Name Reference
------------ ----------------------- ---------
12 SENDER_TSPEC [RFC2205]
Class Type (C-Type):
(TBD1) SSON SENDER_TSPEC [This.I-D]
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IANA is requested to assign the same value for TBD1 and TBD2, and a
value of 8 is suggested.
6. Manageability Considerations
This document makes minor modifications to GMPLS signaling, but does
not change the manageability considerations for such networks.
Clearly, protocol analysis tools and other diagnostic aids
(including logging systems and MIB modules) will need to be enhanced
to support the new traffic parameters and label formats.
7. Implementation Status
[RFC Editor Note: Please remove this entire seciton prior to
publication as an RFC.]
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of
this Internet-Draft, and is based on a proposal described in RFC
6982 [RFC6982]. The description of implementations in this section
is intended to assist the IETF in its decision processes in
progressing drafts to RFCs. Please note that the listing of any
individual implementation here does not imply endorsement by the
IETF. Furthermore, no effort has been spent to verify the
information presented here that was supplied by IETF contributors.
This is not intended as, and must not be construed to be, a catalog
of available implementations or their features. Readers are advised
to note that other implementations may exist.
According to RFC 6982, "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable
experimentation and feedback that have made the implemented
protocols more mature. It is up to the individual working groups to
use this information as they see fit."
7.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)
Organization Responsible for the Implementation:
Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)
Optical Networks and Systems Department
Implementation Name and Details:
ADRENALINE testbed
http://networks.cttc.es/experimental-testbeds/
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Brief Description:
Experimental testbed implementation of GMPLS/PCE control plane.
Level of Maturity:
Implemented as extensions to a mature GMLPS/PCE control plane.
It is limited to research / prototyping stages, but it has been
used successfully for more than the last five years.
Coverage:
Support for the Tspec, FlowSpec, and label formats as described
version 03 of this document. Label format support extends to the
following RSVP-TE objects and sub-objects:
- Generalized Label Object
- Suggested Label Object
- Upstream Label Object
- ERO Label Subobjects
It is expected that this implementation will evolve to follow the
evolution of this document.
Licensing:
Proprietary
Implementation Experience:
Implementation of this document reports no issues.
General implementation experience has been reported in a number
of journal papers. Contact Ramon Casellas for more information or
see
http://networks.cttc.es/publications/?search=GMPLS&research_area=opt
ical-networks-systems
Contact Information:
Ramon Casellas: ramon.casellas@cttc.es
Interoperability:
No report.
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8. Acknowledgments
This work was supported in part by the FP-7 IDEALIST project under
grant agreement number 317999.
9. Security Considerations
This document introduces no new security considerations to [RFC3473].
See also [RFC5920] for a discussion of security considerations for
GMPLS signaling.
10. References
10.1. Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to indicate
requirements levels", RFC 2119, March 1997.
[RFC3473] L. Berger, Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
January 2003.
[G.694.1] ITU-T Recommendation G.694.1 (revision 2), ''Spectral grids
for WDM applications: DWDM frequency grid'', February 2012.
[FLEX-LBL]King, D., Farrel, A. and Y. Li, ''Generalized Labels for
the Flexi-Grid in Lambda Switched Capable (LSC) Label
Switching Routers'', draft-farrkingel-ccamp-flexigrid-
lambda-label, work in progress.
10.2. Informative References
[RFC2205] Braden, R., Zhang L., Berson, S., Herzog, S. and S. Jamin,
''Resource ReServation Protocol (RSVP) -- Version 1,
Functional Specification', RFC2205, September 1997.
[RFC5920] L. Fang et al., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
[RFC6163] Y. Lee, G. Bernstein and W. Imajuku, "Framework for GMPLS
and Path Computation Element (PCE) Control of Wavelength
Switched Optical Networks (WSONs)", RFC 6163, April 2011.
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[RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", RFC 6982, July
2013.
[RFC Editor Note: This reference can be removed when Section 7 is
removed]
[FLEX-FWK] Gonzalez de Dios, O,, Casellas R., Zhang, F., Fu, X.,
Ceccarelli, D., and I. Hussain, ''Framework and
Requirements for GMPLS based control of Flexi-grid DWDM
networks', draft-ogrcetal-cammp-flexi-grid-fwk, work in
progress.
[WSON-SIG] G. Bernstein, Sugang Xu, Y. Lee, G. Martinelli and
Hiroaki Harai, "Signaling Extensions for Wavelength
Switched Optical Networks", draft-ietf-ccamp-wson-
signaling, work in progress.
11. Contributors' Address
Ramon Casellas
CTTC
Av. Carl Friedrich Gauss n7
Castelldefels, Barcelona 08860
Spain
Email: ramon.casellas@cttc.es
Felipe Jimenez Arribas
Telefonica Investigacion y Desarrollo
Emilio Vargas 6
Madrid, 28045
Spain
Email: felipej@tid.es
Yi Lin
Huawei Technologies Co., Ltd.
F3-5-B R&D Center, Huawei Base,
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28972914
Email: yi.lin@huawei.com
Qilei Wang
ZTE
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wang.qilei@zte.com.cn
Haomian Zheng
Huawei Technologies
zhenghaomian@huawei.com
12. Authors' Addresses
Fatai Zhang
Huawei Technologies
Email: zhangfatai@huawei.com
Xian Zhang
Huawei Technologies
Email: zhang.xian@huawei.com
Adrian Farrel
Old Dog Consulting
Email: adrian@olddog.co.uk
Oscar Gonzalez de Dios
Telefonica Investigacion y Desarrollo
Emilio Vargas 6
Madrid, 28045
Spain
Phone: +34 913374013
Email: ogondio@tid.es
Daniele Ceccarelli
Ericsson
Via A. Negrone 1/A
Genova - Sestri Ponente
Italy
Email: daniele.ceccarelli@ericsson.com
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