Re: [Lsr] New Version Notification for draft-wang-lsr-prefix-unreachable-annoucement-03.txt

[Robert Raszuk <[e-mail]>]

Hi Aijun,

> the BGP next-hop is reachable

Nope you missed the crux of the message.

The next hop will be unreachable in the *source area/level. *That would be
where the BGP service route withdraw or aggregate withdraw would originate
at. Same as PUA.

Best,
Robert.


On Mon, Sep 7, 2020 at 11:31 AM Aijun Wang <[e-mail]>
wrote:

> Hi, Robert:
>
> For BGP next-hop tracking, it will help when the BGP next-hop is
> unreachable. But in our situation, the BGP next-hop is reachable, but
> should pass another ABR.
>
> Then, in such situation, the mechanism of BGP next-hop tracking will not
> take effect?
>
> And thanks for your draft information, maybe we can refer to it later J
>
>
>
> Best Regards
>
>
>
> Aijun Wang
>
> China Telecom
>
>
>
>
>
> *From:* [e-mail] [mailto:[e-mail]] *On Behalf Of *Robert
> Raszuk
> *Sent:* Monday, September 7, 2020 4:54 PM
> *To:* Aijun Wang <[e-mail]>
> *Cc:* Les Ginsberg (ginsberg) <[e-mail]>; Gyan Mishra <
> [e-mail]>; Peter Psenak <ppsenak=[e-mail]>;
> Huzhibo <[e-mail]>; Aijun Wang <[e-mail]>; lsr <
> [e-mail]>; Acee Lindem (acee) <[e-mail]>; Xiaoyaqun <
> [e-mail]>; Tony Przygienda <[e-mail]>
> *Subject:* Re: [Lsr] New Version Notification for
> draft-wang-lsr-prefix-unreachable-annoucement-03.txt
>
>
>
> Hi Aijun,
>
> *[WAJ] If necessary, we can advertise the MAX_T_PUA(configurable time for
> the hold of PUA information on the nodes) among the area.*
>
> *If one node connect to the network after the disappearance of the PUA
> destination,  there will be no services can be established/run on these
> failure node/link prefix. *
>
> *It**’s the same as the beginning, as not all of the prefixes can be
> reachable within the summary address.*
>
>
>
> From my pov the only advantage of negative routes in IGP would be to very
> quickly invalidate service routes (within the IGP domain) typically carried
> by BGP.
>
>
>
> When this is accomplished the PUA can indeed time out with no harm.
>
>
>
> Said this - now considering tools like next hop tracking which can trigger
> withdraw or aggregated withdraw(*) proposal in src area I am  really
> curious how much (if anything) we would be gaining here.
>
>
>
> (*) The original proposal for this was written over 15 years ago:
> https://tools.ietf.org/html/draft-raszuk-aggr-withdraw-00  We could
> extend it with next hop which would be the same as IGP PUA prefix.
>
>
>
> Kind regards,
> Robert
>
>
>