Re: [OSPF] [Isis-wg] Mail regarding draft-ietf-ospf-segment-routing-extensions

Peter Psenak <ppsenak@cisco.com> Mon, 29 December 2014 08:32 UTC

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Date: Mon, 29 Dec 2014 09:32:08 +0100
From: Peter Psenak <ppsenak@cisco.com>
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To: Shraddha Hegde <shraddha@juniper.net>, "draft-ietf-ospf-segment-routing-extensions@tools.ietf.org" <draft-ietf-ospf-segment-routing-extensions@tools.ietf.org>, "draft-ietf-isis-segment-routing-extensions@tools.ietf.org" <draft-ietf-isis-segment-routing-extensions@tools.ietf.org>
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Subject: Re: [OSPF] [Isis-wg] Mail regarding draft-ietf-ospf-segment-routing-extensions
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Shraddha,

I do not see how an originator can set any flag regarding the protection 
of the locally attached prefix. It's all the routers on the path towards 
such prefix that need to deal with the protection. Signaling anything 
from the originator seems useless.

thanks,
Peter

On 12/29/14 09:26 , Shraddha Hegde wrote:
> Yes.You are right.
>
> Lets say a prefix sid has a flag "p flag". If this is on it means build a path and provide protection.
> If this is off it means build a path with no protection.
> The receivers of the prefix-sid will build forwarding plane based on this flag.
>
> The applications building the paths will either use prefix-sids with p flag on or off based on the need of the service.
> Rgds
> Shraddha
>
>
> -----Original Message-----
> From: Peter Psenak [mailto:ppsenak@cisco.com]
> Sent: Monday, December 29, 2014 1:49 PM
> To: Shraddha Hegde; draft-ietf-ospf-segment-routing-extensions@tools.ietf.org; draft-ietf-isis-segment-routing-extensions@tools.ietf.org
> Cc: ospf@ietf.org; isis-wg@ietf.org
> Subject: Re: [Isis-wg] Mail regarding draft-ietf-ospf-segment-routing-extensions
>
> Shraddha,
>
> the problem is that the node that is advertising the node-sid can not advertise any data regarding the protection of such prefix, because the prefix is locally attached.
>
> thanks,
> Peter
>
> On 12/29/14 09:15 , Shraddha Hegde wrote:
>> Peter,
>>
>> If there is a service which has to use un-protected path and while
>> building such a path if the node-sids Need to be used (one reason
>> could be label stack compression) , then there has to be unprotected node-sid that this service can make use of.
>>
>> Prefix -sids could also be used to represent different service
>> endpoints which makes it even more relevant to have A means of representing  unprotected paths.
>>
>> Would be good to hear from others on this, especially operators.
>>
>> Rgds
>> Shraddha
>>
>>
>> -----Original Message-----
>> From: Peter Psenak [mailto:ppsenak@cisco.com]
>> Sent: Monday, December 29, 2014 1:35 PM
>> To: Shraddha Hegde;
>> draft-ietf-ospf-segment-routing-extensions@tools.ietf.org;
>> draft-ietf-isis-segment-routing-extensions@tools.ietf.org
>> Cc: ospf@ietf.org; isis-wg@ietf.org
>> Subject: Re: [Isis-wg] Mail regarding
>> draft-ietf-ospf-segment-routing-extensions
>>
>> Shraddha,
>>
>> node-SID is advertised by the router for the prefix that is directly attached to it. Protection for such local prefix does not mean much.
>>
>> thanks,
>> Peter
>>
>> On 12/24/14 11:57 , Shraddha Hegde wrote:
>>> Authors,
>>> We have a "backup flag" in adjacency sid to indicate whether the
>>> label is protected or not.
>>> Similarly. I think we need a flag in prefix-sid as well to indicate
>>> whether the node-sid is to be protected or not.
>>> Any thoughts on this?
>>> Rgds
>>> Shraddha
>>>
>>>
>>> _______________________________________________
>>> Isis-wg mailing list
>>> Isis-wg@ietf.org
>>> https://www.ietf.org/mailman/listinfo/isis-wg
>>>
>>
>> .
>>
>
> .
>