Hi Shraddha, So are you saying that ABR will inject UPA with U Flag when it notices unreachability and it will inject UP Flag when it notices Max Metric ?
And the remote end point receiving UPA will still in both cases result in identical action ? Thx, R On Mon, Mar 27, 2023 at 9:25 PM Shraddha Hegde <shraddha= [email protected]> wrote: > Hi Les, > > Pls see inline for replies. > > > Juniper Business Use Only > > -----Original Message----- > From: Les Ginsberg (ginsberg) <[email protected]> > Sent: Tuesday, March 28, 2023 9:10 AM > To: Shraddha Hegde <[email protected]>; [email protected] > Subject: UPA and planned/unplanned signalling > > [External Email. Be cautious of content] > > > Shraddha - > > To follow up on our discussion over chat at the LSR meeting yesterday... > > At a remote ABR, if BGP had already been told about a planned node > maintenance event (by means that is outside the scope of the UPA draft), > then BGP would have moved traffic away from the node on which the > maintenance event is scheduled in advance of the arrival of the UPA > advertisement. In such a case the arrival of the UPA advertisement would be > of no significance. Since traffic has already moved away it does not matter > whether BGP processes the UPA or does not. > > If, however, BGP had NOT been told about planned maintenance in advance, > the arrival of the UPA should be treated in the same way regardless of > whether the trigger was a planned maintenance event or not. The node > associated with the address advertised in the UPA has become unreachable > and BGP needs to act accordingly. > <SH> This is the case when BGP is not aware of the planned maintenance and > is learning that info from IGP. > You are right that the final outcome of the planned maintenance vs > unreachability is same that the traffic needs to be moved away > >From the remote PE. The difference is in how that is achieved. In case of > unreachability, the action need to be immediate and mechanisms such as > BGP-PIC needed. In case of planned maintenance, it would just be costing > out > Igp metric for the PE and hence the control plane convergence. > There may be implementations which just choose to trigger one mechanisms > for both scenarios and draft does not > Mandate/suggest any of this and is left to implementations. > > > > I therefore see no value add in differentiating between planned/unplanned > in the UPA advertisement. > > I hope this is clear. > Please point out what I might have missed. > > Thanx. > > Les > > _______________________________________________ > Lsr mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/lsr >
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