RE: Updated Draft Liaiosn to Q6/15

"O'Connor, Don" <> Mon, 09 March 2009 23:12 UTC

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Subject: RE: Updated Draft Liaiosn to Q6/15
Date: Mon, 9 Mar 2009 18:12:12 -0500
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Thread-Topic: Updated Draft Liaiosn to Q6/15
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From: "O'Connor, Don" <>
To: "Adrian Farrel" <>, <>


Can you please remove this text

" However, if an implementer chooses to measure impairments
   on their device, this should not be prohibited, and should be

This should be determined by ITU not CCAMP. CCAMP cannot generate
standards that imply ROADM data plane functionality. If any optical
impairments are measured by ROADMs, ITU must first generate the
necessary standard



-----Original Message-----
From: [] On
Behalf Of Adrian Farrel
Sent: Monday, March 09, 2009 4:50 PM
Subject: Updated Draft Liaiosn to Q6/15


Had some comments off-list.

New version with minor changes...


 Dear Peter,

CCAMP experts are looking forward to our joint meeting with Q6/5 on
20th to discuss optical impairments and the control plane operation of 
wavelength switched optical networks (WSONs).

This liaison is to summarise the activity within CCAMP on this subject
far and to set out our objectives for this work.

As you will be aware, the GMPLS control plane is designed to provide a 
dynamic control plane for a variety of switching technologies. Amongst
is the "lambda switch capable" data plane where devices are OEOs,
and photonic cross-connects (PXCs). In fact, lambda switching was the 
technology that led to the development of MPLS from the packet switching

MPLS control plane.

The IETF's CCAMP working group is the design authority for all
extensions to 
the GMPLS family of protocols.

The original work on lambda switching networks within CCAMP recognised
there is a subset of optical networks in which it is possible to
optical impairments and where the number of regeneration points is high.
these environments, path computation can be performed on a reachability 
graph, and lambda conversion can be performed as necessary within the 

As PXCs were introduced into WSONs, it remained the case that optical 
impairments could be disregarded by the control plane. Where necessary, 
optimal impairment-aware paths could be computed off-line and supplied
the control plane, leaving the control plane to handle establishment of 
connections and recovery after failure. Failure recovery scenarios might

lead to contention for wavelengths or suboptimal optical paths, but
could be handled by crankback within the signaling protocol.

More recent work on WSONs indicates that the proportion of pure optical 
devices (ROADMs and PXCs) is increasing. This means that it is necessary
compute paths that offer end-to-end lambda continuity. This problem
the routing and wavelength assignment (RWA) problem) must be solved, and
be compounded by devices with limited cross-connect capabilities (for 
example, with glass-through, a limited OEO matrix, or restricted 
port-to-port capabilities). In approaching this problem it is convenient
there is a common identification scheme for wavelengths across the whole

network (previously, wavelength identification was a local matter
the nodes at the ends of each link). To aid with this, the CCAMP working

group has developed
 that provides a protocol-independent encoding for wavelengths in a way
is compliant with G.694. Further work on this problem space can be seen
the following CCAMP documents:

"Framework for GMPLS and PCE Control of Wavelength Switched Optical

"Routing and Wavelength Assignment Information Model for Wavelength
Optical Networks"

"Routing and Wavelength Assignment Information Encoding for Wavelength 
Switched Optical Networks"

CCAMP participants have further identified cases where they believe it
be helpful to consider optical impairments during the control plane 
operation of a WSON. This gives rise to four distinct deployment

1. No concern for impairments or lambda continuity.
   (Original GMPLS)
2. No concern for impairments, but lambda continuity is
    important. (The RWA problem)
3. Concern for "basic" impairments
4. Concern for "advanced" impairments

In focusing on the third of these categories, CCAMP intends to base its
on G.680 and related recommendations with the following understanding:
- G.680 (et al.) provides a complete list of simple constraints
- Where G.680 refers to "single vendor" domains, it does not
   mean single manufacturer, but rather "single system integrator".
   That is, the equipment is not "plug and play", but has been
   tested to interoperate and the network has been planned.
- There is no requirement to measure impairments.
   - Many networks are engineered such that configured
      impairment values are enough information
   - Measuring can often produce ambiguous values
   - Equipment to perform measurement may be expensive
   However, if an implementer chooses to measure impairments
   on their device, this should not be prohibited, and should be

 With this in mind, CCAMP is looking to Q6/15 to work as a partner in 
- the complete list of impairments suitable for this type of network
   - and the complete list of Recommendations to use as references
- the rules by which such impairments are accumulated along a path
- generic encodings and ranges of values for the impairments

 For reference, some early work on impairment-aware GMPLS is listed
This work is not yet adopted as CCAMP work, but is likely to form the
of such work once we have discussed the way forward with Q6/15.

"A Framework for the Control of Wavelength Switched Optical Networks
with Impairments"

 "Information Model for Impaired Optical Path Validation"

Looking forward to a profitable meeting,
Deborah Brungard and Adrian Farrel
CCAMP Working Group Co-Chairs