I missed this in my first comments ;( I share the concern expressed by
Don.
I suggest that we turn this into a question that we can debate with Q6.
e.g. replace
"- 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
accommodated."
with:
"We understand that Q6 currently has no requirement to measure
impairments
after the transport equipment is deployed.
- Currently networks are engineered such that configured
impairment values are enough information
Does Q6 foresee any value in the future for transport equipment
including the ability to measure the actual impairments on a path.
Malcolm Betts
Nortel Networks
Phone: +1 613 763 7860 (ESN 393)
email: betts01@nortel.com
-----Original Message-----
From: owner-ccamp@ops.ietf.org [mailto:owner-ccamp@ops.ietf.org] On
Behalf Of Giovanni Martinelli
Sent: Tuesday, March 10, 2009 5:19 AM
To: O'Connor, Don
Cc: Adrian Farrel; ccamp@ops.ietf.org
Subject: Re: Updated Draft Liaiosn to Q6/15
O'Connor, Don wrote:
Adrian
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
accommodated."
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
Although I understand there could be some precedences I would not the
remove the text. In principle the RWA problem try to catch some data
plane constrains as well.
Cheers,
G
Regards
Don
-----Original Message-----
From: owner-ccamp@ops.ietf.org [mailto:owner-ccamp@ops.ietf.org] On
Behalf Of Adrian Farrel
Sent: Monday, March 09, 2009 4:50 PM
To: ccamp@ops.ietf.org
Subject: Updated Draft Liaiosn to Q6/15
Hi,
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
March 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
so 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
these is the "lambda switch capable" data plane where devices are
OEOs, ROADMs, 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
that there is a subset of optical networks in which it is possible to
disregard optical impairments and where the number of regeneration
points is high.
In
these environments, path computation can be performed on a
reachability graph, and lambda conversion can be performed as
necessary within the network.
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 to 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
these 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 to compute paths that offer end-to-end lambda continuity.
This problem (called the routing and wavelength assignment (RWA)
problem) must be solved, and may 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 if there is a common identification
scheme for wavelengths across the whole
network (previously, wavelength identification was a local matter
between the nodes at the ends of each link). To aid with this, the
CCAMP working
group has developed
http://www.ietf.org/internet-drafts/draft-ietf-ccamp-gmpls-g-694-lambd
a-
labels-03.txt
that provides a protocol-independent encoding for wavelengths in a
way that is compliant with G.694. Further work on this problem space
can be seen in the following CCAMP documents:
"Framework for GMPLS and PCE Control of Wavelength Switched Optical
Networks (WSON)"
http://www.ietf.org/internet-drafts/draft-ietf-ccamp-rwa-wson-framewor
k-
01.txt
"Routing and Wavelength Assignment Information Model for Wavelength
Switched Optical Networks"
http://www.ietf.org/internet-drafts/draft-ietf-ccamp-rwa-info-01.txt
"Routing and Wavelength Assignment Information Encoding for Wavelength
Switched Optical Networks"
http://www.ietf.org/internet-drafts/draft-ietf-ccamp-rwa-wson-encode-00.
txt
CCAMP participants have further identified cases where they believe it
would be helpful to consider optical impairments during the control
plane operation of a WSON. This gives rise to four distinct deployment
scenarios:
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 work 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
accommodated.
With this in mind, CCAMP is looking to Q6/15 to work as a partner in
establishing:
- 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
below.
This work is not yet adopted as CCAMP work, but is likely to form the
basis of such work once we have discussed the way forward with Q6/15.
"A Framework for the Control of Wavelength Switched Optical Networks
(WSON)
with Impairments"
http://www.ietf.org/internet-drafts/draft-bernstein-ccamp-wson-impairm
en
ts-02.txt
"Information Model for Impaired Optical Path Validation"
http://www.ietf.org/internet-drafts/draft-bernstein-wson-impairment-in
fo
-00.txt
Looking forward to a profitable meeting, Deborah Brungard and Adrian
Farrel CCAMP Working Group Co-Chairs