Internet Engineering Task Force M. Kattan, Ed.
Internet-Draft G. Martinelli
Intended status: Informational D. Bianchi
Expires: April 17, 2011 Cisco
October 14, 2010
WSON Wavelenght Property Information
draft-kattan-wson-property-00
Abstract
Wavelength Switched Optical Network will extend GMPLS protocols to to
manage wavelength across DWDM optical networks. In many situations
the control plane needs to know additional information regarding
wavelengths. The current proposal identify a way to carry some
property information along with wavelength information. Control
plane can leverage the knowledge of such properties during its
operations.
Status of this Memo
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This Internet-Draft will expire on April 17, 2011.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2. Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Lambda Properties Definitions . . . . . . . . . . . . . . . . . 5
4. Lambda Properties Encoding . . . . . . . . . . . . . . . . . . 6
4.1. OSPF Extensions . . . . . . . . . . . . . . . . . . . . . . 6
4.2. RSVP Extensions . . . . . . . . . . . . . . . . . . . . . . 7
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
One of the current Generalized MPLS (GMPLS) evolutions is toward the
Wavelength Switched Optical Networks (WSON) as described in
[I-D.ietf-ccamp-rwa-wson-framework]. A related work is defined
within [I-D.ietf-ccamp-gmpls-g-694-lambda-labels] defining the GMPLS
label in a format suitable for Lambda Switched Capable (LSC
equipments).
Todays WSON networks are implemented through DWDM technologies and
they treats all light paths as equal regardless of the type of data,
bandwidth and mission criticality of the traffic it is carrying.
This draft suggests the introduction of some properties like
prioritizing light paths for scenarios such as restoration, fiber
congestion and resource contention. This could be achieved in
assigning properties information to each light path. Following
sections will describe some scenarios where such information will be
useful. How those information are assigned is out of the scope of
this draft.
1.1. Requirements Language
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].
2. Scenarios
The following list identify several scenarios occurring in operating
WSON networks where some wavelength information will help. Note that
this scenarios are triggered by the availability of new
reconfigurable equipments allowing new level of flexibility within
DWDM networks.
Example of this hardware would be multi-degree Reconfigurable Optical
Add Drop Multiplexers or ROADMs to support mesh DWDM networks. Fiber
1 is an example of a meshed DWDM network where multiple light path
are being set up to and from node C.
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+++++
+ B +
+++++
/ | \ A-C Fiber has 30 wavelengths setup
/ | \ D-C Fiber has 20 Wavelengths setup
/ +++ \
/ + D + \
/ / +++ \ \ Most wavelengths on B-C fiber are used, only
/ / \ \ 10 wavelengths are still available.
/ / \ \
+++++ \ +++++
+ A + ----------- + C +
+++++ +++++
Figure 1
(a) Prioritize then Restore
With the reference to Figure 2 we can consider a dual fiber cut
on the path A-C and D-C. A lambda prioritization might be used
to ensure high priority light paths be served first. This will
ensure both a faster restoration time compared to other channels
as well as the ability of high priority light paths to grab
first (before other lower priority light paths) the available
resources on the working fiber.
+++++
+ B +
+++++
/ | \ A-C Fiber has 30 wavelengths setup
/ | \ D-C Fiber has 20 Wavelengths setup
/ +++ \
/ + D + \ Question is which wavelengths out of the 50
/ / +++ \ \ are going to be restored (selection of
/ / X \ 10 only)?
/ / \ \
+++++ \ +++++
+ A + ---- X ---- + C +
+++++ +++++
Figure 2
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(b) Revertive Operation
In this scenario, a fiber is being restored and hence having a
high priority light paths restored first might or might not be
desirable. Setting a revertive or not revertive option would be
useful in this scenario. Moreover, in the event of multiple
fiber cuts with only one fiber restored as an example,
prioritizing light paths will ensure higher priority traffic
will get the best service as well as up time once the WSON
restoration mechanism kicks in. Other possibilities inlcude
defining some others lambda properties like a "no not restore
bit" or "Wait time to restore" to allow the control plane
operates according to different restoration strategies.
(c) Network Optimization
Similar to revertive operation, prioritizing light paths will
also be useful in network optimization. High priority traffic
will always get the option to ride on the best available fiber
path. Also high priority light path could be provided with the
option to get the best performance OI parameters to chose from.
(d) Service Level Agreement support
This could be useful for DWDM service providers where light
paths are tagged with different parameters so that to create a
desirable and configurable level of SLA. This SLA could be
derived from bandwidth (100G, 40G and 10G), traffic type (TDM vs
IP/Eth or FC payload) or just a network management defined
requirement.
(e) Resource Contention
In the event of one or multiple fiber cuts, we could be faced
with a situation whereby the number of light paths to be
restored is larger than the available light path resources on
the working fiber (see Figure 2 above). Having light paths
prioritization together with a wait-time-to-restore will ensure
that the high priority traffic will be served first and hence
will be able to grab the available resources first.
3. Lambda Properties Definitions
This section provide a list of wavelengths properties that worths to
include in a control plane.
Priority. This information will allow a preferred treatment to a
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wavelength with higher priority.
Do Not Restore. If this information will not restore try to restore
the wavelength after a failure.
Wait-Time-to-Restore. This information will report a time elapsed
before a wavelength go through a restoration process.
Hold-OfF-Time.
4. Lambda Properties Encoding
The lambda priority will be encoded over three bits. There are
different encoding possibility depending on the protocol used to
distribute this information over the control plane.
It worth noting that GMPLS extension in [RFC4202] and [RFC4203]
already define LSP priority bandwidth within Interface Switching
Capability Descriptor sub-TLV. This concept however does not suffice
for WSON LSP for the scenario represented above.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | HOT | WTR |R| PRI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3
The 3 bits PRI field represent the lambda priority encoding. Zero
means no priority, Seven means maximum priority
R is the "Do not restore bit". If set the wavelength will be exclude
from any restoration
WRT is the wait time to restore. 5 bits with a granularity of 0.5
second will allow up to 16 seconds of delay on restoration.
Hold Off timer.
4.1. OSPF Extensions
In order to improve the WSON path computation it make sense to add
such information through the chosen IGP. Current WSON proposal are
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available for OSPF-TE extentions.
Document [I-D.ietf-ccamp-rwa-wson-encode] report the information on
how to encode Dynamic Link Information through the label set
specification.
Efficient encoding through a Link Attributes shall be identified. An
initial proposal may looks like the label set attribute as explained
in the following picture. The wavelength property encoding will be a
sub-TLV (type TBD) of the link TLV. The set of
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBD | Reserved | Length = 16 bytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n for lowest frequency = -11 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Wavelength Property Field <1> |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Wavelength Property Field <n> |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4
Where:
TBD: is the sub-TLV type (to be defined)
The Grid provide the current WSON wavelength encoding in use and
must match with the label set defined in
[I-D.ietf-ccamp-general-constraint-encode].
A list of Wavelength property field, defined n Figure 4 in an
order they match with the last label set advertised.
4.2. RSVP Extensions
WSON signalling extentions are reported through
[draft-bernstein-ccamp-wson-signaling-07]. In addition to this a new
LSP_ATTRIBUTES as defined in [RFC5420] will be required to carry the
lambda priority information.
A new LSP_ATTRIBUTE shall include the Wavelength Property Field as
defined in Figure 4
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5. Acknowledgements
6. IANA Considerations
This memo includes no request to IANA.
All drafts are required to have an IANA considerations section (see
the update of RFC 2434 [I-D.narten-iana-considerations-rfc2434bis]
for a guide). If the draft does not require IANA to do anything, the
section contains an explicit statement that this is the case (as
above). If there are no requirements for IANA, the section will be
removed during conversion into an RFC by the RFC Editor.
7. Security Considerations
All drafts are required to have a security considerations section.
See RFC 3552 [RFC3552] for a guide.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
8.2. Informative References
[I-D.ietf-ccamp-general-constraint-encode]
Bernstein, G., "General Network Element Constraint
Encoding for GMPLS Controlled Networks",
draft-ietf-ccamp-general-constraint-encode-03 (work in
progress), October 2010.
[I-D.ietf-ccamp-gmpls-g-694-lambda-labels]
Otani, T., Rabbat, R., Shiba, S., Guo, H., Miyazaki, K.,
Caviglia, D., Li, D., and T. Tsuritani, "Generalized
Labels for Lambda-Switching Capable Label Switching
Routers", draft-ietf-ccamp-gmpls-g-694-lambda-labels-07
(work in progress), April 2010.
[I-D.ietf-ccamp-rwa-wson-encode]
Bernstein, G., "Routing and Wavelength Assignment
Information Encoding for Wavelength Switched Optical
Networks", draft-ietf-ccamp-rwa-wson-encode-05 (work in
progress), July 2010.
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[I-D.ietf-ccamp-rwa-wson-framework]
Bernstein, G., Lee, Y., and W. Imajuku, "Framework for
GMPLS and PCE Control of Wavelength Switched Optical
Networks (WSON)", draft-ietf-ccamp-rwa-wson-framework-07
(work in progress), October 2010.
[I-D.narten-iana-considerations-rfc2434bis]
Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs",
draft-narten-iana-considerations-rfc2434bis-09 (work in
progress), March 2008.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
July 2003.
Authors' Addresses
Moustafa Kattan (editor)
Cisco
DUBAI, 500321
UNITED ARAB EMIRATES
Phone: + 1 408 527 5101
Email: mkattan@cisco.com
Giovanni Martinelli
Cisco
Italy
Phone: +39 039 209 2044
Email: giomarti@cisco.com
David Bianchi
Cisco
Italy
Phone: +39 039 209
Email: davbianc@cisco.com
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