Re: [Idr] BGP-LS extension for inter-as topology retrieval in different scenario

Hi Ketan, Aijun,

On Tue, Mar 20, 2018 at 10:13 AM, Ketan Talaulikar (ketant) <
ketant@cisco.com> wrote:

> Hi Aijun,
>
>
>
> Perhaps the comments provided during the IDR WG meeting yesterday on this
> draft were not clear and would like to share the same on the list.
>
>
>
> 1)     The “Redistributed Routes Originator TLV” is not necessary and if
> your intention is to determine the originating router for redistributed
> routes then this is already solved as follows:
>
> a.      The Prefix NLRI descriptor includes the Node descriptor which
> allows determination of the originator of the redistribution point router.
>
> b.      The Source Router ID TLV is required in ISIS only because the
> redistribution point router may be in a different level/area and unlike
> OSPF where the flooding for type 5 is AS scope, this TLV is required for
> ISIS. The BGP-LS spec allows use of this Source Router ID TLV for any
> protocol in general, if required.
>
> 2)     The 2nd part of your draft which relates to signalling of inter-AS
> TE links is required and missing from the current BGP-LS specs AFAIK.
> However, the draft is not handling this properly. The new TLVs which you
> have listed in sec 3.3.2 need to be introduced as new Link Descriptor TLVs
> – not as attributes. While descriptor and attribute TLVs are taken from the
> same registry, they are very different from packaging perspective. So the
> draft needs to be fixed to correct this.
>
>
>

   The Link NLRI (NLRI Type = 2) is shown in the following figure.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+
     |  Protocol-ID  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                           Identifier                          |
     |                            (64 bits)                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //               Local Node Descriptors (variable)             //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //               Remote Node Descriptors (variable)            //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                  Link Descriptors (variable)                //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 8: The Link NLRI Format

The Autonomous System sub-TLV is part of both Local and Remote Node
Descriptors.
For inter-AS link, the AS sub-TLV (as part of the Remote node descriptor)
carry the remote AS number?
Do we really need a new sub-TLV? 

Or am I missing something? 

Thanks!
Dhruv

> In summary, your draft does address a gap with respect to signalling of
> inter-AS TE links from IGPs into BGP-LS, but there is no gap when it comes
> to determination of redistributed route’s originators.
>
>
>
> Thanks,
>
> Ketan
>
>
>
> *From:* Idr <idr-bounces@ietf.org> *On Behalf Of *Aijun Wang
> *Sent:* 05 March 2018 11:13
> *To:* idr@ietf.org
> *Subject:* [Idr] BGP-LS extension for inter-as topology retrieval in
> different scenario
>
>
>
> Hi, All:
>
>
>
> We just uploaded one draft at https://datatracker.ietf.org/
> doc/draft-wang-idr-bgpls-inter-as-topology-ext/ to describe the BGP-LS
> extension for inter-as topology retrieval in different scenarios.
>
> We are also applying the time slot on the upcoming IETF 101 meeting to
> present this topic. Any comments are welcome.
>
>
>
> The abstracts of this draft are the followings:
>
> This document describes new TLVs extended for BGP-LS to transfer the
> originator of redistributed routes and other inter-AS TE related TLVs to
> let the SDN controller to retrieve the network topology automatically under
> the multi-domain environments.
>
> This extension can expand the usage of BGP-LS protocol to multi-domain;
> enable the network operator to collect the connection relationship between
> different domains and then calculate the overall network topology
> automatically based on the information provided by BGP-LS protocol.
>
>
>
>
>
> Best Regards.
>
>
>
> Aijun Wang
>
> Network R&D and Operation Support Department
>
> China Telecom Corporation Limited Beijing Research Institute,Beijing,
> China.
>
>
>
>
>
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