Re: [Isis-wg] 答复: 答复: 答复: [OSPF] Inconsistency between OSPF extention and IS-IS extension for segment routing

Peter Psenak <ppsenak@cisco.com> Fri, 08 November 2013 20:38 UTC

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Date: Fri, 08 Nov 2013 12:37:20 -0800
From: Peter Psenak <ppsenak@cisco.com>
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To: Xuxiaohu <xuxiaohu@huawei.com>
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Cc: "ospf@ietf.org" <ospf@ietf.org>, "isis-wg@ietf.org" <isis-wg@ietf.org>
Subject: Re: [Isis-wg] 答复: 答复: 答复: [OSPF] Inconsistency between OSPF extention and IS-IS extension for segment routing
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Xiaohu,

OSPF SR draft clearly states that newly defined Extended Prefix Opaque
LSAs do not contribute to the prefix reachability. What you are asking
for is to negate that and install forwarding entries based on what is in
the EP-LSA, without prefix being advertised in any regular LSA. Once you
start to do that you will end up with all sorts of problems. I would
like to keep the current definition in place.


thanks,
Peter


On 11/8/13 12:04 , Xuxiaohu wrote:
> Hi Peter,
> 
> Sure. However, why not borrow the idea of longest-matching algorithm proposed in that RFC to SR?
> 
> BR,
> Xiaohu
> 
> ________________________________________
> 发件人: isis-wg-bounces@ietf.org [isis-wg-bounces@ietf.org] 代表 Peter Psenak [ppsenak@cisco.com]
> 发送时间: 2013年11月9日 3:56
> 收件人: Xuxiaohu
> 抄送: ospf@ietf.org; isis-wg@ietf.org
> 主题: Re: [Isis-wg] 答复: 答复: [OSPF] Inconsistency between OSPF extention and IS-IS extension for segment routing
> 
> Xiaohu,
> 
> there is no LDP in the SR network, so RFC5283 is not applicable.
> 
> thanks,
> Peter
> 
> On 11/7/13 17:28 , Xuxiaohu wrote:
>> Hi Peter,
>>
>> The 'longest-match algorithm' for LIB installation has been proposed by RFC5283.
>>
>> Best regards,
>> Xiaohu
>>
>> ________________________________________
>> 发件人: Peter Psenak [ppsenak@cisco.com]
>> 发送时间: 2013年11月8日 8:39
>> 收件人: Xuxiaohu
>> 抄送: ospf@ietf.org; isis-wg@ietf.org
>> 主题: Re: 答复: [OSPF] Inconsistency between OSPF extention and IS-IS extension for segment routing
>>
>> Xiaohu,
>>
>> On 11/7/13 16:23 , Xuxiaohu wrote:
>>>
>>> Hi Peter,
>> ]
>>> if you aggregate on area/L1L2 boundary, SIDs/labels for individual
>>> prefixes that are covered by the aggregate are useless in the area to
>>> which you aggregate - there will be no FIB entries for these individual
>>> prefixes in such area. So if you aggregate, there is no need to
>>> propagate SIDs/labels for aggregated prefixes.
>>>
>>> [Xiaohu] "In the multi-area/level
>>>       scenario where route summary between areas/levels is required, the IP
>>>       longest-match algorithm SHOULD be used by SR-capable routers when
>>>       processing label bindings advertised by the mapping server" For more details, please read the Introduction section of http://tools.ietf.org/html/draft-xu-rtgwg-global-label-adv-00
>>
>> I don't understand. If you summarize, then only the summary prefix will
>> be visible in the backbone (and remote areas) and installed in the FIB
>> on all routers in these areas.
>>
>> Where would you apply 'longest-match algorithm' when you only see the
>> single summary? How would you use the SID/label for prefixes that are
>> covered by the summary?
>>
>> thanks,
>> Peter
>>
> 
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