AS_PATH length and route selection (WAS: Strange BGP announcement)
Deepak Jain
deepak at ai.net
Wed Nov 18 22:51:35 UTC 1998
Best guess approximation? Say not more than 1 minute per router (* N
router hops between 1 edge of network and the other?) typically more like
10 seconds on moderately loaded routers/links? Assuming you aren't
re-establishing each iBGP session from scratch and only receiving an
update from 1 connection (peer or customer)?
Does that sound reasonable?
-Deepak.
On Wed, 18 Nov 1998, Sean M. Doran wrote:
> Ben Black wrote:
>
> | The key to this is that the administrative preference in question has domain
> | scope. Assuming you are correctly implementing iBGP, whether with a full
> | mesh, reflectors, or confederations, and assuming consistent announcements
> | from external route originators, then you can't make a loop because the
> | same policy is in effect for all the routers in the AS.
>
> You will not form a *persistent* loop or black-hole. However,
> as there is invariably some degree of propagation delay among iBGP
> speakers, particularly in a large network, there can be short-lived
> loops or black-holes when converging upon routing changes.
>
> Sean.
>
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