Re: [Pce] Comment on draft-ietf-pce-pcecp-interarea-reqs-00.txt

Hi,

On Jan 12, 2006, at 10:40 PM, zhangrenhai 18605 wrote:

> Hi, JP
>
> Sorry for seeing your reply so late.
> Thanks, see inline.
>
> ----- Original Message -----
> From: JP Vasseur <jvasseur@cisco.com>
> Date: Thursday, January 5, 2006 3:07 am
> Subject: Re: [Pce] Comment on draft-ietf-pce-pcecp-interarea- 
> reqs-00.txt
>
>> Hi ,
>>
>> On Dec 28, 2005, at 2:03 AM, Zhang Renhai wrote:
>>
>>> Hi, Jean-Louis
>>>
>>>  I have some comment on the draft draft-ietf-pce-pcecp-interarea-
>>
>>> reqs-00.txt
>>>
>>>  In section 7.11.1, In case of network failure, jittering will
>> be
>>> used to avoid
>>> simultaneous requests sent to one PCE. Could more consideration
>> be
>>> given here to
>>> the preemptment, becouse the jittering timeout is stochastic,
>> some
>>> lower request
>>> may be served before a higher request and the path may be
>>> calculated differently.
>>> which may increase the probability of a preemptment.
>>>
>>
>> The decision on the PCC request scheduling is out of the scope of
>> this ID. Note that the point that you mentioned also applies to
>> the
>> located-PCE case.
> I am not sure what scope this point belongs to. I just considered  
> more about what
> has been mentioned in the draft.
> Is this consideration important anough to be added somewhere?

You're very welcome to discuss the topic on the list but PCC request  
request scheduling are not standardized.

>>
>>>
>>>  I have always been thinking a question: if a PCC will not
>> perform
>>> the CSPF
>>> computation, why does it still maintain the TEDB any longer?
>> which
>>> may consume
>>> a lot of memory and CPU of a LSR.This question dost not aid at
>> this
>>> draft.
>>>
>>
>> Because
>> (1) The PCE may decide to use a remote PCE for some LSPs and not
>> for
>> others (for instance, inter versus intra-domain)
>> (2) The PCE may decide to always use a PCE and fall back to local
>> path computation or loose hop routing under specific conditions
> Agree, I just want to be convinced if some routers acting as a pure  
> PCC
> (no longer perform path computation)can save some CPU and memory so
> there could be a lower requirement on capability to these routers
> in PCE-based environment.Maybe this is a benefit to PCE Architecture.

Sure, this is an option already described in the draft.

>>
>>>  In inter-area environment,sometimes, a PCC may wish to get as
>> many
>>> paths as possible,
>>> for all kinds of purpose,so could the PCC send the request to
>> more
>>> than one PCEs?
>>>
>>
>> Yes, although this would clearly be very sub-optimal ....
> I am not sure your point, could you please expand your explanation  
> any more?
> In my opinion, a ABR acting as a PCE usually can not have a full AS- 
> scope information of TED.
> so it may return a sub-optimal compuation result compared to some
> latent path which can be returned by other ABR linked to a different
> area. I know this can be solved by a ABR through sending the  
> request to multiple
> ABR in a area, otherwise, how to solve this problem?

Yes stay tuned ... I'll resurrect soon a draft that used to be  
discussed in CCAMP detailing these aspects.

Thanks.

JP.

>
>
> Thanks,
> Zhang
>
>>
>> JP.
>>
>>> Regards,
>>> Zhang
>>> _______________________________________________
>>> Pce mailing list
>>> Pce@lists.ietf.org
>>> https://www1.ietf.org/mailman/listinfo/pce
>>
>>

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