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

Pushpasis Sarkar <psarkar@juniper.net> Mon, 05 January 2015 06:16 UTC

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From: Pushpasis Sarkar <psarkar@juniper.net>
To: Pushpasis Sarkar <psarkar@juniper.net>, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>, Shraddha Hegde <shraddha@juniper.net>, "Peter Psenak (ppsenak)" <ppsenak@cisco.com>, "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>, Hannes Gredler <hannes@juniper.net>
Thread-Topic: [OSPF] [Isis-wg] Mail regarding draft-ietf-ospf-segment-routing-extensions
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Date: Mon, 5 Jan 2015 06:16:35 +0000
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Subject: Re: [OSPF] [Isis-wg] Mail regarding draft-ietf-ospf-segment-routing-extensions
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Some typo correction inline..

On 1/5/15, 11:43 AM, "Pushpasis Sarkar" <psarkar@juniper.net> wrote:

>Hi Les,
>
>
>On 1/5/15, 11:23 AM, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com> wrote:
>
>>Pushpasis -
>>
>>The key point is that the proposal does not have any lasting impact on
>>traffic flow. A simple topology should suffice to illustrate this.
>>
>>
>>A----B----C----D
>>          |       |
>>          E----F
>>
>>(All links have the same cost)
>>
>>Suppose we wish to have traffic entering at A flow along the path A-B-C-D
>>- but if the link B---C fails we do NOT want traffic to take the path
>>B--E--F--C.
>>
>>You propose to have C advertise an address with two node-sids - one which
>>allows protection - call it C(P) - and one which does NOT allow
>>protection - call it C(NP).
>[Pushpasis] No. My proposal is for D to advertise two node sids, D1 with
>NP set to 0 and D2 with NP set to 1. Applications on route A that do not
>need B,
>or C to protect the A-B-C-D path will use D2. B and C will not install
>backup paths for D2. Other apps can use D1 as they are supposed to do
>otherwise. Wether to protect D1 or not is a local decision of B and C.
>Hope I could clarify enough :)
>
>>
>>If the label stack specifies C(NP) - then while the link B--C is UP
>>everything works as desired (primary path to C(NP) on Node B is via link
>>B-C).
>>However, when the link B--C goes down, the network will reconverge and in
>>a modest amount of time the new primary path to C(NP) on node B will be
>>via link B-E.
>[Pushpasis] Yes agreed. But only applications on A will be injecting
>traffic using D2. Once the B-C link-down event reaches router A will stop
>injecting traffic using D2. A path re-compute will be triggered on A. Yes
>I agree that if B converges D2 (not FRR) before A re-compute, there is
>still chance that some small amount of traffic is sent over A-B-E-F-C-D.
>
>>
>>The existence of C(NP) therefore only affects traffic flow during the
>>reconvergence period i.e. if we assume B did NOT install a repair path
>>for C(NP) traffic will be dropped only until a new primary path is
>>calculated. I don’t see the value in this.
>>
>>As a (somewhat dangerous) aside, the functionality you are looking for is
>>more akin to "not-via" as defined in RFC 6981 - though I am quick to add
>>that I am NOT proposing to pursue that. :-)
>>But reading that RFC might give you more insight into why simply setting
>>"don't protect" for a prefix isn't useful for the purpose you have in
>>mind.
>>
>>   Les
>>
>>
>>
>>-----Original Message-----
>>From: Pushpasis Sarkar [mailto:psarkar@juniper.net]
>>Sent: Sunday, January 04, 2015 8:34 PM
>>To: Les Ginsberg (ginsberg); Shraddha Hegde; Peter Psenak (ppsenak);
>>draft-ietf-ospf-segment-routing-extensions@tools.ietf.orgtf.org;
>>draft-ietf-isis-segment-routing-extensions@tools.ietf.orgtf.org; Hannes Gredler
>>Cc: ospf@ietf.org; isis-wg@ietf.org
>>Subject: Re: [OSPF] [Isis-wg] Mail regarding
>>draft-ietf-ospf-segment-routing-extensions
>>
>>Hi Les,
>>
>>Please find comments inline..
>>
>>Authors, 
>>
>>Here is my proposal. Please let me know if this sounds reasonable or not.
>>
>>- A new ŒNo-Potection-Required¹ or ŒNP¹ flag be added to the Prefix-SID
>>Sub-TLV/TLV. Setting this flag means none of the transit routers should
>>try to protect this node-segment.
>>- Let nodes advertise two node-sid-index each (per address-family), one
>>without and one with ŒNP¹ flag set. For node-sid advertised with ŒNP¹
>>flag 0, routers same behave the same way as today. But when they receive
>>a node-sid with ŒNP¹ flag set, they avoid/skip finding a backup for that
>>segment.
>>- Finally ingress servers or TE-applications may use these 'node-sids
>>with NP-flag set¹ for use cases where it is better to drop traffic on
>>topology outages rather than diverting it to some other paths. For such
>>cases ingress router or TE-applications should look for node-sids with
>>ŒNP¹ flag set and not the regular node-sids. For all other normal use
>>cases(including L3VPN/6VPE etc) traffic should be carried using node-sid
>>without ŒNP‹flag set.
>>
>>Thanks and Regards,
>>-Pushpasis
>>
>>On 1/5/15, 3:37 AM, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com> wrote:
>>
>>>Pushpasis -
>>>
>>>I don't agree.
>>>
>>>The use of one node-sid vs another has nothing whatever to do with the
>>>request Shraddha has made i.e. should we introduce a flag indicating
>>>whether a particular prefix should be protected or not. A node-sid only
>>>dictates what (intermediate) node traffic should be sent to - not what
>>>link(s) are used to reach that node.
>>[Pushpasis] This is not about which links to take. It is about wether
>>transit routers should try to protect the node-segment to the this
>>node-sid or not. I think this opens up a lot many number of possibilities
>>on the ingress router and TE controller-based applications.
>>
>>>
>>>Adjacency-sids have a different semantic - they identify the link over
>>>which traffic is to be forwarded. Identifying an adjacency-sid as
>>>unprotected means traffic will NEVER flow over a different link. There
>>>is no equivalent behavior w a node-sid - which is what this discussion
>>>has been about.
>>[Pushpasis] I am not trying to draw a parallel between this new flag and
>>the ŒB¹ flag in Adj-Sid SubTlv. Like said before
>>
>>>
>>>   Les
>>>
>>>
>>>-----Original Message-----
>>>From: Pushpasis Sarkar [mailto:psarkar@juniper.net]
>>>Sent: Sunday, January 04, 2015 8:51 AM
>>>To: Les Ginsberg (ginsberg); Shraddha Hegde; Peter Psenak (ppsenak);
>>>draft-ietf-ospf-segment-routing-extensions@tools.ietf.org.ietf.org;
>>>draft-ietf-isis-segment-routing-extensions@tools.ietf.org
>>>Cc: ospf@ietf.org; isis-wg@ietf.org
>>>Subject: Re: [OSPF] [Isis-wg] Mail regarding
>>>draft-ietf-ospf-segment-routing-extensions
>>>
>>>Hi Les,
>>>
>>>I think the requirement Shraddha is referring is about the choice of
>>>exact node-sid to use while constructing the label-stack for a
>>>explicit-LSP on the ingress router, which will be typically done after
>>>running some CSPF on the SPRING topology. And not the IGP on ingress or
>>>transit routers.
>>>
>>>Thanks
>>>-Pushpasis
>>>
>>>On 1/3/15, 3:10 AM, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
>>>wrote:
>>>
>>>>Shraddha -
>>>>
>>>>IGPs today do NOT perform constraint based SPFs - so I don't know why
>>>>you believe that the primary SPF will meet a set of constraints that
>>>>an LFA calculation will not. In fact , it is the opposite which is
>>>>true because implementations today do support preferences in choosing
>>>>LFAs based on various configured policy - something which is NOT done
>>>>for primary SPF.
>>>>
>>>>If you want a certain class of traffic to avoid a subset of the links
>>>>in the topology then you need to have a way of identifying the links
>>>>(NOT the node addresses) and a way of calculating a path which only
>>>>uses the links which meet the constraints of that class of service.
>>>>Identifying a particular prefix as protected or unprotected won't
>>>>achieve that.
>>>>
>>>>   Les
>>>>
>>>>-----Original Message-----
>>>>From: Shraddha Hegde [mailto:shraddha@juniper.net]
>>>>Sent: Friday, January 02, 2015 10:54 AM
>>>>To: Les Ginsberg (ginsberg); Peter Psenak (ppsenak);
>>>>draft-ietf-ospf-segment-routing-extensions@tools.ietf.orgols.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
>>>>
>>>>Hi Les/Peter,
>>>>
>>>>      When reconvergence happens, the primary path will be calculated
>>>>based on all constriants.
>>>>This is not true with the protection path.Protection path is
>>>>calculated locally (LFA/RLFA)  and does not consider the
>>>>characteristics of the services running on that path.
>>>>It's easier for some services to pick the unprotected path when the
>>>>nature of the service is that it can be restarted  when there is a
>>>>disconnection.
>>>>
>>>>Rgds
>>>>Shraddha
>>>>-----Original Message-----
>>>>From: Les Ginsberg (ginsberg) [mailto:ginsberg@cisco.com]
>>>>Sent: Friday, January 02, 2015 10:06 PM
>>>>To: Peter Psenak (ppsenak); Shraddha Hegde;
>>>>draft-ietf-ospf-segment-routing-extensions@tools.ietf.orgols.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
>>>>
>>>>Peter -
>>>>
>>>>The requirement Shraddha specified was to not allow a particular class
>>>>of service ("heavy bandwidth services" was the example provided) to
>>>>use certain links in the topology. My point is that advertising a flag
>>>>for a given prefix which says "do not calculate a repair path for this
>>>>prefix"
>>>>does not help achieve this. Once the network reconverges following the
>>>>failure of one of the links on which "heavy bandwidth services" is
>>>>allowed/preferred it is quite likely that the new best path will be
>>>>over a link on which "heavy bandwidth services" is NOT
>>>>allowed/preferred. This will happen whether you have the new flag or
>>>>not - so the flag will have no lasting effect. It would only affect
>>>>traffic flow during the brief period during which the network is
>>>>reconverging.
>>>>
>>>>I think you and I are actually in agreement - I am simply sending a
>>>>stronger negative message - not only do I think the flag is not useful
>>>>- I think it does not achieve the goal Shraddha has in mind.
>>>>
>>>>   Les
>>>>
>>>>
>>>>-----Original Message-----
>>>>From: Peter Psenak (ppsenak)
>>>>Sent: Friday, January 02, 2015 12:18 AM
>>>>To: Les Ginsberg (ginsberg); Shraddha Hegde;
>>>>draft-ietf-ospf-segment-routing-extensions@tools.ietf.orgols.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
>>>>
>>>>Hi Les,
>>>>
>>>>I believe the idea is not to exclude any particular link, it's
>>>>actually much simpler - do not calculate backup for the prefix if the
>>>>flag is set.
>>>>
>>>>I'm still not quite sure how useful above is, but technically it is
>>>>possible.
>>>>
>>>>thanks,
>>>>Peter
>>>>
>>>>On 12/30/14 17:22 , Les Ginsberg (ginsberg) wrote:
>>>>> Shraddha -
>>>>>
>>>>> When performing a best path calculation whether a given link is in
>>>>>the set of best paths (to be protectedED) or not (could be used as a
>>>>>protectING path) is a function of the topology - not the link.  If
>>>>>there is a topology change it is quite likely that a given link will
>>>>>change from being a protectED link to being a protectING link (or
>>>>>vice versa).
>>>>>So what you propose regarding node-SIDs would not work.
>>>>>
>>>>> In the use case you mention below if you don't want a certain class
>>>>>of traffic to flow on a given link it requires a link attribute which
>>>>>is persistent across topology changes. There are ways to do that -
>>>>>using Adj-SIDs is one of them. But using node-SIDs in the way you
>>>>>propose is NOT.
>>>>>
>>>>>     Les
>>>>>
>>>>> -----Original Message-----
>>>>> From: OSPF [mailto:ospf-bounces@ietf.org] On Behalf Of Shraddha
>>>>> Hegde
>>>>> Sent: Monday, December 29, 2014 10:12 PM
>>>>> To: Peter Psenak (ppsenak);
>>>>> 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: [OSPF] [Isis-wg] Mail regarding
>>>>> draft-ietf-ospf-segment-routing-extensions
>>>>>
>>>>> Peter,
>>>>>
>>>>>> The requirement here is to get an un-protected path for services
>>>>>>which do not want to divert the traffic on protected path in any
>>>>>>case.
>>>>>
>>>>>> can you give an example of such a service and a reasoning why such
>>>>>>service would want to avoid local protection along the path?
>>>>>
>>>>> Heavy bandwidth services are potential candidates.  The network is
>>>>>well planned and well provisioned for primary path but same is not
>>>>>true for backup paths.
>>>>> Diverting heavy bandwidth services along protection path can disrupt
>>>>>the other services on that path, they are better-off un-protected so
>>>>>that an event in the network Would result in disconnection and a
>>>>>retry for such services.
>>>>>
>>>>> Rgds
>>>>> Shraddha
>>>>>
>>>>> -----Original Message-----
>>>>> From: Peter Psenak [mailto:ppsenak@cisco.com]
>>>>> Sent: Monday, December 29, 2014 4:35 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,
>>>>>
>>>>> On 12/29/14 10:06 , Shraddha Hegde wrote:
>>>>>> Peter,
>>>>>>
>>>>>> The requirement here is to get an un-protected path for services
>>>>>>which do not want to divert the traffic on protected path in any
>>>>>>case.
>>>>>
>>>>> can you give an example of such a service and a reasoning why such
>>>>>service would want to avoid local protection along the path?
>>>>>
>>>>> thanks,
>>>>> Peter
>>>>>
>>>>>> So when the originator of node-sid signals un-protected path
>>>>>>requirement, there is always an unprotected path.
>>>>>>
>>>>>> Regarding the protected path, it is the default behavior as it
>>>>>>exists today. You get protection if it's available otherwise you
>>>>>>don't get protection.
>>>>>>
>>>>>> In fact, you can have the new flag to say "NP flag" meaning
>>>>>>non-protected flag which can be set for the unprotected path.
>>>>>> By default it remains off and gives the behavior as it exists today.
>>>>>>
>>>>>>
>>>>>> Rgds
>>>>>> Shraddha
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Peter Psenak [mailto:ppsenak@cisco.com]
>>>>>> Sent: Monday, December 29, 2014 2:26 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 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
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> .
>>>>>>>>>
>>>>>>>>
>>>>>>>> .
>>>>>>>>
>>>>>>>
>>>>>>> .
>>>>>>>
>>>>>>
>>>>>> .
>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> OSPF mailing list
>>>>> OSPF@ietf.org
>>>>> https://www.ietf.org/mailman/listinfo/ospf
>>>>> .
>>>>>
>>>>
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>>
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