Subject: [Capwap] LACK OF CONSENSUS: 2-port/mux issue

From: Margaret Wasserman <[email-masked]>
Date: Tue, 10 Oct 2006 10:53:41 -0400

Hi All,

Over the past few months, we have had an open issue in the CAPWAP WG  
that we refer to as the "2-port/mux issue".  The current CAPWAP  
protocol specification indicates that the CAPWAP protocol will run  
over two UDP ports, one for control traffic and one for data  
traffic.  Proposals have been made to move to a single-port approach  
or to allow for a single-port option.

There has been much discussion of this issue, including e-mail  
discussion and presentations at WG meetings.  We have consulted with  
the IESG, and the outcome of those discussions has been sent to the  
group.  At this point, we believe that every interested party has had  
an opportunity to present technical facts in support of his/her  
position, and we believe that the WG is aware of the technical  
differences between the two approaches.  So, it is time to determine  
the resolution of this issue.

The WG chairs have reviewed the status of this issue, and we have  
found that the WG does not have consensus to modify the  
demultiplexing mechanism described in the current CAPWAP  
specification, either to move to a single-port approach or to add a  
single-port option.  Therefore, in the absence of any new technical  
information, we are closing this discussion.  Editors, please close  
this issue in the issue tracker with a resolution indicating that  
there is no WG consensus to make this change.

We realize that this has been a contentious issue for the WG, and  
that some people may be dissatisfied with this resolution.  We all  
would have preferred our technical discussions to converge on a  
single correct choice, but that hasn't happened.  In this case, it is  
possible to build a viable CAPWAP protocol using either approach, and  
both approaches have advantages and disadvantages that are weighed  
differently by different parties.  Unless new technical information  
comes to light, we do not believe that continued discussion of this  
issue will lead to consensus on the technical superiority of either  
approach.

The WG chairs have reviewed the history of this issue to determine  
how to move forward, given that our technical discussions have not  
converged.  The two-port approach was part of the original LWAPP  
specification, and It was also included in the -00 version of the  
CAPWAP specification that was accepted as a WG work item in early  
2006.  There was WG consensus to accept LWAPP as the basis of the  
CAPWAP specification, therefore the WG chairs believe that WG  
consensus would be required to change the demultiplexing mechanism.   
Despite lengthy discussion, the WG has not reached consensus to do that.

We would like to thank everyone who has participated in this  
discussion.  We hope that we will be able to put this issue behind us  
and continue to work together towards a well-defined and widely- 
deployed CAPWAP specification.

Best Regards,

Dorothy Gellert, Mahalingam Mani & Margaret Wasserman
The CAPWAP WG Co-Chairs

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