One document matched: draft-zhang-ccamp-flexible-grid-rsvp-te-ext-03.txt
Differences from draft-zhang-ccamp-flexible-grid-rsvp-te-ext-02.txt
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: May 12, 2014 November 12, 2013
RSVP-TE Signaling Extensions in support of Flexible Grid
draft-zhang-ccamp-flexible-grid-rsvp-te-ext-03.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 new flexible optical grid.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with
the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
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This Internet-Draft will expire on May 12, 2014.
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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.................................... 6
5. IANA Considerations ......................................... 7
5.1. RSVP Objects Class Types................................ 7
6. Manageability Considerations................................. 7
7. Security Considerations...................................... 7
8. References .................................................. 8
8.1. Normative References.................................... 8
8.2. Informative References.................................. 8
9. Contributors' Address........................................ 8
10. Authors' Addresses ..........................................9
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
for defining applications. 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 fixed bandwidth 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 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.
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[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 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].
A 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 types of
architecture approaches to RSA: combined RSA, separated RSA and
distributed SA. The first two approaches are referred to as
"centralized SA", because both routing and spectrum (frequency slot)
assignment are performed by centralized entity before the signaling
procedure.
In the case of centralized SA, the assigned frequency slot is
specified in the 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 involved network elements to select
the frequency slot to be used.
If the capability of switching or converting the whole optical
spectrum allocated to an optical spectrum LSP is not available at
nodes along the path of the LSP, the LSP is subject to the Optical
"Spectrum Continuity Constraint", as described in [FLEX-FWK].
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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
equivalent of optical bandwidth, although the amount of bandwidth
associated with a slot width will depend on the 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 a flexi-LSP.
This information is required in 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:
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 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.
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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
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.
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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 (8 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 multiple
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.
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.
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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]
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. Acknowledgments
This work was supported in part by the FP-7 IDEALIST project under
grant agreement number 317999.
8. Security Considerations
This document introduces no new security considerations to [RFC3473].
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9. References
9.1. 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.
9.2. 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.
[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.
[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.
10. Contributors' Address
Ramon Casellas
CTTC
Av. Carl Friedrich Gauss n7
Castelldefels, Barcelona 08860
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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
11. 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
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Genova - Sestri Ponente
Italy
Email: daniele.ceccarelli@ericsson.com
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