Re: [OSPF] Poll for WG adoption of draft-hegde-ospf-node-admin-tag

Peter Psenak <ppsenak@cisco.com> Tue, 26 August 2014 15:43 UTC

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Date: Tue, 26 Aug 2014 17:43:48 +0200
From: Peter Psenak <ppsenak@cisco.com>
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To: Hannes Gredler <hannes@juniper.net>
References: <D0212051.2116%acee@cisco.com> <53FC3FD8.1000704@cisco.com> <D022049C.2295%acee@cisco.com> <53FC9A02.4080401@cisco.com> <20140826153201.GA6179@juniper.net>
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Subject: Re: [OSPF] Poll for WG adoption of draft-hegde-ospf-node-admin-tag
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Hi Hannes,

On 8/26/14 17:32 , Hannes Gredler wrote:
> hi peter,
>
> operators want to assign node-tags as per router function (ABR, PE, core) and then
> the LFA-selection becomes much easier to specify. - e.g.
> - only pick a LFA that does not cross another PE router.
>
> similarily it is desirable for "LFA tunnel termination"
> to put out a constraint which says
> - only pick a PQ neighbor which has node tag 'X'

my point is that with the above approach you have to:
1. On candidate PQ nodes configure the tag X
2. on all other nodes configure "only pick a PQ neighbor which has node 
tag 'X'"

It's (2) which makes me feel uncomfortable, as it's a config to be 
applied to many nodes.

If we instead define a capability bit which would mean "PQ candidate", 
we would avoid (2).

>
> i found it always strange that we for TE (as an example for
> constraining paths) we have got ways to tag links, but
> not way to tag nodes - that draft aims to fix that.

I'm not against tagging nodes as such. What worries me if we end up 
using node tags for signalling capabilities of node.

thanks,
Peter

>
> HTH,
>
> /hannes
>
> On Tue, Aug 26, 2014 at 04:30:26PM +0200, Peter Psenak wrote:
> | Hi Acee,
> |
> | On 8/26/14 15:45 , Acee Lindem (acee) wrote:
> | >Hi Peter,
> | >This is a valid concern and one that we¹ve discussed previously with
> | >respect to routing behavior based on policies. I think that accepting this
> | >draft as a WG document should not preclude standardization of capabilities
> | >advertisement for popular applications.
> |
> | sure. Just that the draft mentions applications like "Controlling Remote LFA
> | tunnel termination", which I'm not sure the node tag is the best approach
> | for.
> |
> | thanks,
> | Peter
> |
> | >Thanks,
> | >Acee
> | >
> | >On 8/26/14, 4:05 AM, "Peter Psenak (ppsenak)" <ppsenak@cisco.com> wrote:
> | >
> | >>On 8/25/14 23:18 , Acee Lindem (acee) wrote:
> | >>>There are situations where node level policy is required and an OSPF
> | >>>advertised admin tag simplifies this. For example, advertisement of
> | >>>remote-LFA eligibility.
> | >>
> | >>my concern with the generic use of admin tags for signaling capability
> | >>is that it's operationally unfriendly compared to explicit signaling of
> | >>the capability (e.g. using a bit or a TLV). The reason is that you have
> | >>to configure the tag meaning on all receiving routers.
> | >>
> | >>thanks,
> | >>Peter
> | >>
> | >>>
> | >>>Please indicate your support or objections to adopting this draft as an
> | >>>OSPF WG document.
> | >>>
> | >>>Thanks,
> | >>>Acee
> | >>>
> | >>>
> | >>>_______________________________________________
> | >>>OSPF mailing list
> | >>>OSPF@ietf.org
> | >>>https://www.ietf.org/mailman/listinfo/ospf
> | >>>
> | >>
> | >>_______________________________________________
> | >>OSPF mailing list
> | >>OSPF@ietf.org
> | >>https://www.ietf.org/mailman/listinfo/ospf
> | >
> | >.
> | >
> |
> | _______________________________________________
> | OSPF mailing list
> | OSPF@ietf.org
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> .
>