Hi, Robert: We are discussing how and when to back to the normal state before UPA is triggered, not how to configure BGP active/backup via Local_Pref Attribute.
Or, let’s change the statement in more general manner: How to revoke the UPA explicitly when the prefix is reachable again? Please note “stopping sending UPA” is not equal to “revoking the UPA”. For example, in BGP, when you want to revoke some prefixes, you will advertise explicitly “withdrawn” prefixes , not just stopping sending the related BGP Updates. Aijun Wang China Telecom > On May 29, 2025, at 18:33, Robert Raszuk <[email protected]> wrote: > > >> >> Once that’s done, the ABR can safely withdraw the UPA, and the network >> remains stable (i.e. from R1 perspective the backup egress router became the >> new primary egress router once BGP converged because session with R2 failed). >> [WAJ] Then, R1 will keep using the backup egress router forever? When, how >> and what trigger the R1 switchback to the original egress router? >> > > Even without UPA at all in the picture if operators chooses active/backup > scheme (as opposed to active/active model) for multihomed sites or networks > typically BGP paths carry properly set LOCAL_PREF attribute. > > UPA does not have anything to do with it. > > Thx, > R. > > >
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