Re: [Idr] draft-uttaro-idr-bgp-persistence-00: Security Considerations

[Robert Raszuk <[e-mail]>]

Extending the question ...

 > How long RR will wait after coming up to get his previous IBGP
 > peering reestablished before starting the cleanup ?

Actually RR can not do any cleanup if RR - PE2 never comes up can it ? 
It seems that PE1 will continue in this case to keep zombie paths PE2 
via RR forever.

The possible solution would be for PE1 to not only invalidate paths with 
"blinked" next hop, but also when previously lost session given paths 
were received over got reestablished. But I do not think draft mandates 
such behaviour.

R.

> Eric,
>
>> If PE1 happens to have noticed that PE2 blinked out, it may be wise
>> for PE1
>> to invalidate the routes for which PE2 is the next hop. If PE1 did not
>> notice that PE2 blinked out, it will continue to make use PE2's old
>> VPN-IP
>> routes.
>
> So when RR is down PE2's BGP process restarts while IGP not - PE1 has no
> chance to notice any next hop blink - hence till RR comes up and cleans
> up the mess pretty much network is in a bad state.
>
> How long RR will wait after coming up to get his previous IBGP peering
> reestablished before starting the cleanup ?
 >
 >            / PE2
 > PE1 -- RR
 >            \ PE3
 >
> Thx,
> R.