Re: [CCAMP] The description of Path Key retaining time in RFC5553

Cyril,

A very nice note regarding a very nice draft.  I have a few questions for clarification, viz, is the reason why 'Path Key' is called that because it deals with paths and not LSPs?  Given this, doesn't our 'stateful PCE thingy', as defined by Zafar, need to maintain path state and not LSP state?  Given the transient nature of LSPs doesn't this actually make a lot of sense?

Yours Irrespectively,

John

From: ccamp-bounces@ietf.org [mailto:ccamp-bounces@ietf.org] On Behalf Of Cyril Margaria
Sent: Friday, November 15, 2013 12:09 PM
To: Zafar Ali (zali)
Cc: ccamp@ietf.org
Subject: Re: [CCAMP] The description of Path Key retaining time in RFC5553

Hi,
please see inline for comments.

On 15 November 2013 04:12, Zafar Ali (zali) <zali@cisco.com<mailto:zali@cisco.com>> wrote:

-----Original Message-----
From: Fatai Zhang <zhangfatai@huawei.com<mailto:zhangfatai@huawei.com>>
Date: Monday, November 11, 2013 9:09 PM
To: zali <zali@cisco.com<mailto:zali@cisco.com>>, "Zhangxian (Xian)" <zhang.xian@huawei.com<mailto:zhang.xian@huawei.com>>
Cc: "ccamp@ietf.org<mailto:ccamp@ietf.org>" <ccamp@ietf.org<mailto:ccamp@ietf.org>>
Subject: RE: The description of Path Key retaining time in RFC5553

>Please don't argue scaliblity issue because you can see even a GMPLS node
>can store lots of informaiton.
>
Fatai-

I did not get what you are saying. What I was saying is:

* Tunnel-id is 16 bit. I.e., client name space is 16 bit. There can be
more than one LSP per tunnel.
* Path key is 16 bits. I.e., server name space is 16 bits. Each LSP needs
a Path Key.

I do not recall that each LSP needs a path key, each path does, but not each LSP.
So the scalability is not related to amount of LSPs, but the amount of path use, which scale quite differently than the number of LSPs.

* There is 1:N relationship between PCC and PCE (server). PCE sever may
even be centralized.
* You are requiring (Path key, path info) "state" to be stored at the PCE
server for the life time of the connections.

That is correct, the PCE need to keep a state on the path used, but using the term statefull in that case is confusing and misleading, as its tied to a full LSP DB. TED itself is a state too.
* Path keys have hold-off timer of 30 minutes before they can be reused.

Hence, in your solution, PCE server would run out of Path Keys much before
clients runs out of tunnel name space. In your solution, if you have a
centralized PCE, you can only support 64K connection IN THE NETWORK! I am
not sure why you want to ignore these scaling restrictions.
as stated before, you would support a maximum of 64k Paths, given the diversity constraint you want to support.
In any case the scaling of the solution is to be considered, but is there other problem with that solution?
This solution is attractive as it provides a complete solution ( deploy a PCE colocated with the LSR, only resolving  PKS, the rest is already defined).

Regards,
Cyril.
Thanks

Regards...Zafar

>

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