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

Peter Psenak <ppsenak@cisco.com> Mon, 29 December 2014 08:56 UTC

Return-Path: <ppsenak@cisco.com>
X-Original-To: ospf@ietfa.amsl.com
Delivered-To: ospf@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id D913D1A0041; Mon, 29 Dec 2014 00:56:36 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -14.511
X-Spam-Level:
X-Spam-Status: No, score=-14.511 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001, T_RP_MATCHES_RCVD=-0.01, USER_IN_DEF_DKIM_WL=-7.5] autolearn=ham
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id EXkS-eobpFRM; Mon, 29 Dec 2014 00:56:34 -0800 (PST)
Received: from aer-iport-4.cisco.com (aer-iport-4.cisco.com [173.38.203.54]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 6C3851A0040; Mon, 29 Dec 2014 00:56:33 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=5018; q=dns/txt; s=iport; t=1419843393; x=1421052993; h=message-id:date:from:mime-version:to:cc:subject: references:in-reply-to:content-transfer-encoding; bh=1KDv1D4mgiL9fvHeNGND6BX06z20o1aZgudykXDi3Ng=; b=cNqbk6XRt4IE3Oesh0RafeReFccMSLBmPUtSoUXnDG+yB+t/O/3mk56r 7LtQ5DzlKHlXIdQPJVMApvSUSXzywT2TJS9LKwSE0H1f0zQ1Pi/6zZMvy YuVWK3DLqxVV6/bFpLpnVkva7fOMWEBdw8hN7clcVGkrXJP9dD3PYjgBG o=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AsEEALQWoVStJssW/2dsb2JhbABcg1hYxmQKhXMCgSEBAQEBAX2EDAEBAQMBAQEBNTYKAQwECxEEAQEBCRYIBwkDAgECARUfCQgGAQwBBQIBAYggCA3FDAEBAQEBAQEBAQEBAQEBAQEBAQEBARMEjwwaAQFKBQcGhCMBBJcIhgSLTCKDbz0xgQyBNwEBAQ
X-IronPort-AV: E=Sophos;i="5.07,659,1413244800"; d="scan'208";a="286661942"
Received: from aer-iport-nat.cisco.com (HELO aer-core-3.cisco.com) ([173.38.203.22]) by aer-iport-4.cisco.com with ESMTP; 29 Dec 2014 08:56:30 +0000
Received: from [10.61.76.181] (ams3-vpn-dhcp3253.cisco.com [10.61.76.181]) by aer-core-3.cisco.com (8.14.5/8.14.5) with ESMTP id sBT8uT2u006533; Mon, 29 Dec 2014 08:56:30 GMT
Message-ID: <54A1173D.6000200@cisco.com>
Date: Mon, 29 Dec 2014 09:56:29 +0100
From: Peter Psenak <ppsenak@cisco.com>
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:24.0) Gecko/20100101 Thunderbird/24.4.0
MIME-Version: 1.0
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>
References: <BY1PR0501MB13819883015276791F20D631D5540@BY1PR0501MB1381.namprd05.prod.outlook.com> <54A10B35.4030301@cisco.com> <BY1PR0501MB1381B131A68B321264B7E930D5510@BY1PR0501MB1381.namprd05.prod.outlook.com> <54A10E78.6030006@cisco.com> <BY1PR0501MB1381610E47F46E81528B5416D5510@BY1PR0501MB1381.namprd05.prod.outlook.com> <54A11188.8040301@cisco.com> <BY1PR0501MB1381860D81EE3DF32A76B6D7D5510@BY1PR0501MB1381.namprd05.prod.outlook.com>
In-Reply-To: <BY1PR0501MB1381860D81EE3DF32A76B6D7D5510@BY1PR0501MB1381.namprd05.prod.outlook.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Archived-At: http://mailarchive.ietf.org/arch/msg/ospf/xR_xc1a0VkahT14lkzvlfY2hylU
Cc: "ospf@ietf.org" <ospf@ietf.org>, "isis-wg@ietf.org" <isis-wg@ietf.org>
Subject: Re: [OSPF] [Isis-wg] Mail regarding draft-ietf-ospf-segment-routing-extensions
X-BeenThere: ospf@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: The Official IETF OSPG WG Mailing List <ospf.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ospf>, <mailto:ospf-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/ospf/>
List-Post: <mailto:ospf@ietf.org>
List-Help: <mailto:ospf-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ospf>, <mailto:ospf-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 29 Dec 2014 08:56:37 -0000

Shraddha,

I do not see how an originator of the node-sid can mandate a protection 
for the prefix on other routers. What if there is no backup available on 
a certain node along the path?

The parallel with the B-flag in adj-sids is not right - in case of 
adj-sid the originator has the knowledge about the local adjacency 
protection and as such can signal it it it's LSA.

thanks,
Peter


On 12/29/14 09:47 , Shraddha Hegde wrote:
> Peter,
>
>
> Pls see inline.
>
> Rgds
> Shraddha
>
> -----Original Message-----
> From: Peter Psenak [mailto:ppsenak@cisco.com]
> Sent: Monday, December 29, 2014 2:02 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,
>
> I do not see how an originator can set any flag regarding the protection of the locally attached prefix.
> <Shraddha> The originator advertises 2 node-sids. One with p flag set and the other without the p-flag set.
>
>   It's all the routers on the path towards such prefix that need to deal with the protection.
> <Shraddha> The receiving nodes will download protected path for the node-sid with p-flag set and download
> Unprotected path for the node-sid with p-flag unset.
>
> Signaling anything from the originator seems useless.
> <Shraddha>  For node-sids it's the others who need to build the forwarding plane but it's only the originator who can signal which of
>                          Sid need to be built with protection and which not. Other routers on the path cannot signal this information.



>
> With this you have two paths for the node. One is protected and the other is unprotected. This meets the requirement of having an un-protected path.
>
> It's very much in parallel to B-flag in adj-sids. It is similar to advertising multiple adj-sids one with B-flag on and other with b-flag off , to get protected and unprotected
> Adj-sids.
>
> 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
>>>>
>>>
>>> .
>>>
>>
>> .
>>
>
> .
>