Re: [CCAMP] Working group lastcall:draft-ietf-ccamp-gmpls-vcat-lcas-08

["Sadler, Jonathan B." <[e-mail]>]

Hi Greg,

There have been a number of different liaisons from ITU that have talked about the separation of control plane instances on a layer-by-layer basis and the limits this places on what signaling information can be carried by the other instance.  Three that are quite pertinent to this discussion are as follows:

  https://datatracker.ietf.org/documents/LIAISON/file537.pdf - states "VCAT is viewed as a layer of its own and has its own call controller. As per the interlayer architecture in G.8080 section 6.6, the VCAT call would be associated with a server layer call or calls, each of which would have/own one or more server layer connections.  It is these connections that are part of the VCG. "
  https://datatracker.ietf.org/documents/LIAISON/file419.doc - states "signalling messages are always scoped to a specific layer - the information elements in the server layer signalling messages are specific to the server layer (e.g. containing only server layer resources in the ERO) and the information elements in the client layer signalling messages are specific to the client layer (e.g. containing only client layer resources in the ERO)."
  https://datatracker.ietf.org/documents/LIAISON/file432.doc - states "if two layers are under different administrative domains because they belong to two different providers, the amount of information that can be shared between the two domains is more limited than in the case where a single provider network provides resources at all layers"



As pointed out by Evelyne, the MLN/MRN drafts/RFCs place the CALL_ATTRIBUTES object in the server layer (i.e. STS/VC) signaling messages, while it is being used to carry client layer (i.e. VCAT) detail.  This is the piggybacking issue (i.e. carrying client layer data in the server layer signaling) that I referenced in the comment I made earlier.



Why is this not good?  Well, if the client layer and server layer are in different control contexts, it becomes unsafe to assume what service the other control context will provide.  For example:

 - the client layer could be using a control plane protocol while the server layer is being manually/statically configured

 - the client layer doesn't have access to the information being exchanged by a server layer control plane instance

 - the server layer network utilizes a control plane protocol other than one specified by the IETF

 - the server layer network's policy is to not allow the passing of arbitrary data in its control plane



In all of these cases, the CALL_ATTRIBUTES object would not make it between the endpoints, causing the VCAT to not be established.



This sort of separation information has been provided in other IETF protocols (e.g. T-LDP used for PW setup - it's separate from the RSVP-TE setup done in for the Tunnel LSP) - we're just looking for the same sort of separation to be provided for inverse multiplexing configuration mechanisms.



Jonathan Sadler


________________________________
From: [e-mail] [mailto:[e-mail]] On Behalf Of Evelyne Roch
Sent: Thursday, December 10, 2009 1:22 PM
To: Greg Bernstein
Cc: CCAMP
Subject: Re: [CCAMP] Working group lastcall:draft-ietf-ccamp-gmpls-vcat-lcas-08

Greg,

The dependency is problematic in networks that follow the ASON architecture because of the administrative boundaries. I would like to see implementations that are compliant with this draft and the ASON architecture.

Evelyne

________________________________
From: Greg Bernstein [mailto:[e-mail]]
Sent: Thursday, December 10, 2009 2:10 PM
To: Roch, Evelyne (CAR:Q840)
Cc: BRUNGARD, DEBORAH A (ATTLABS); CCAMP
Subject: Re: [CCAMP] Working group lastcall:draft-ietf-ccamp-gmpls-vcat-lcas-08
Hi Evelyne, why is this dependency problematic? What are you trying to do and what it the context?

Greg

Evelyne Roch wrote:
Greg,

There is a problem in the architecture because the CALL_ATTRIBUTES is carrying group info in the member call, creating a dependency on the members to achieve VCAT signaling. That dependency is problematic in a network with administrative boundaries.

Evelyne

________________________________
From: Greg Bernstein [mailto:[e-mail]]
Sent: Thursday, December 10, 2009 1:29 PM
To: Roch, Evelyne (CAR:Q840)
Cc: BRUNGARD, DEBORAH A (ATTLABS); CCAMP
Subject: Re: [CCAMP] Working group lastcall:draft-ietf-ccamp-gmpls-vcat-lcas-08
Hi Evelyne, version 04 published in February of 2008 contained a "Call_Data_Object", with a TLV containing exactly the information and utilizing the same procedures that we are now using with the CALL_ATTRIBUTES object.
It was recommended by the WG chairs to use the CALL_ATTRIBUTES object as defined in the MLN-Extensions work rather than defining another "Call_data_object". None of of the procedures were changed from 04.
Is there a problem with functionality? We worked very hard to find a technique utilizing existing mechanisms to give some support forthe member sharing scenario. We do not preclude other techniques being used in the future.

Greg

Evelyne Roch wrote:
This liaison was referring to version 04, before the introduction of CALL_ATTRIBUTES in the draft, exactly where the problem is.

In the laison 429, the ITU-T agrees to one call per VCG. That is the VCAT call (not addressed in the draft right now).

As far as member calls, members could be in same or different calls based on application (for diverse routing -> could be same call, for protection/restoration -> could be different calls). That is the member call used in the draft.

The problem is that CALL_ATTRIBUTES is carried in member call signaling when it pertains to the VCG, i.e. VCAT call.

Evelyne





________________________________
From: Greg Bernstein [mailto:[e-mail]]
Sent: Thursday, December 10, 2009 11:16 AM
To: Roch, Evelyne (CAR:Q840)
Cc: BRUNGARD, DEBORAH A (ATTLABS); CCAMP
Subject: Re: [CCAMP] Working group lastcall:draft-ietf-ccamp-gmpls-vcat-lcas-08
Hi Evelyne, I'll add some text to the requirements section to clarify "common pool" per your request.
The "call concept" usage and "member sharing scenario" have been previously discussed, liaised, and resolved with ITU-T.


https://datatracker.ietf.org/liaison/415/



It includes:

ITU: "Per Question 5:  We understand that this draft is only addressing

the

constituent server layer call; i.e., not the ASON multilayer call

supporting call construct. However, we suggest that you do not preclude

extensions to use a call in the VCAT layer.



CCAMP response: As noted above, this is not precluded. We look forward to

future communication from you as you progress this work."



Q14 later responded saying they were satisfied with the one call

construct:

https://datatracker.ietf.org/liaison/429/
Greg

Evelyne Roch wrote:
Greg,

Normally, I would expect the requirements section to be clear enough that it helps define a proper solution mechanism and clearly sets the scope, not the other way around (i.e. you need to read the mechanism to understand how the requirements should be interpreted).

My main concern is how the "call concept" is being used with the member sharing scenario, as I mentioned earlier in this thread. The calls (in the draft) are really member calls, not VCAT group calls. But the call attributes contain VCAT group information. I don't want the  member call to attribute carry call information for the entire VCAT group.

Evelyne

________________________________
From: Greg Bernstein [mailto:[e-mail]]
Sent: Wednesday, December 09, 2009 5:34 PM
To: Roch, Evelyne (CAR:Q840)
Cc: BRUNGARD, DEBORAH A (ATTLABS); CCAMP
Subject: Re: [CCAMP] Working group lastcall:draft-ietf-ccamp-gmpls-vcat-lcas-08
Hi Evelyne, the common pool is a set of potential member signals that have been set up using the mechanisms defined in the draft, particularly the VCAT call procedures. The draft allows these to be "shared" amongst different VCGs over time. Note that at any given point in time a member signal can belong to only one VCG. Note that by the nature of VCAT that these are signals that have the same source and destination. The procedures section makes this fairly clear.

Greg



Evelyne Roch wrote:
Greg,

First, I think we need to further clarify the requirements as I'm not sure all the readers will interpret the requirements the same way. What exactly does it mean to be "in a common pool"?

Evelyne

________________________________
From: Greg Bernstein [mailto:[e-mail]]
Sent: Tuesday, December 08, 2009 1:04 PM
To: Roch, Evelyne (CAR:Q840)
Cc: BRUNGARD, DEBORAH A (ATTLABS); CCAMP
Subject: Re: [CCAMP] Working group lastcall:draft-ietf-ccamp-gmpls-vcat-lcas-08
Hi Evelyne, the main focus on this work was to support VCGs with diversely routed routed members. We were asked to include the member sharing scenario and formulated a method to accommodate it without significantly increasing the complexity of the messages involved.  It seems to us that the solution included in this draft provides sufficient functionality to meet the requirements in the document. Is there a scenario you think is within the scope of the draft that is not addressed?

Greg

Evelyne Roch wrote:

Greg, see below.





-----Original Message-----

From: Greg Bernstein [mailto:[e-mail]]

Sent: Friday, December 04, 2009 4:09 PM

To: Roch, Evelyne (CAR:Q840)

Cc: BRUNGARD, DEBORAH A (ATTLABS); CCAMP

Subject: Re: [CCAMP] Working group



lastcall:draft-ietf-ccamp-gmpls-vcat-lcas-08



<snip>





I'm not sure that we have calls of calls in GMPLS. At the time this

was written this wasn't deemed desirable.





The model of calls being supported by calls is clearly support by ASON,

whether at the same layer (see G.8080 section 6.7) or different layer

(section 6.6). I find it highly desirable.



<snip>



Evelyne









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Dr Greg Bernstein, Grotto Networking [phone]







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Dr Greg Bernstein, Grotto Networking [phone]







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Dr Greg Bernstein, Grotto Networking [phone]







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Dr Greg Bernstein, Grotto Networking [phone]







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Dr Greg Bernstein, Grotto Networking [phone]