-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 One could also presume that BFD should also be considered dangerous, if enabled. - - ferg - -- Pascal Gloor <pascal.gloor@spale.com> wrote:

Is it likely that BGP times out before underlying IP topology reconvergences after a link/node failure? Do service providers ever set such low values of BGP timeouts that BGP timeout will occur?

If not, what else may cause a BGP session to time out?

Depending on your hardware, you can trigger your BGP and IGP to shut sessions when the peer is gone. On some cisco, you can have BFD (Bidirectional Forwarding Detection). you have to enable this on both sides. If BFD notices the peer is down, it will notify OSPF,BGP,... (if configured so). for example: ! interface GigabitEthernet0/0 ip address 10.1.1.1 255.255.255.252 bfd neighbor 10.1.1.2 bfd interval 250 min_rx 250 multiplier 3 ip ospf bfd ! This will send a BFD packet every 250ms, expect one every 250ms and if 3 packets are missed (after 750ms) it will tell OSPF to shut any session towards 10.1.1.2 (or routed via 10.1.1.2 for the BGP case). Pascal -----BEGIN PGP SIGNATURE----- Version: PGP Desktop 9.6.1 (Build 1012) wj8DBQFGNvYRq1pz9mNUZTMRAjKOAKDTAyIHrxZMjzuBmzCG54Mz1jWOZwCfVYzj DG01G8MGXfV/KQ27Pj6N58Y= =HfOW -----END PGP SIGNATURE----- -- "Fergie", a.k.a. Paul Ferguson Engineering Architecture for the Internet fergdawg(at)netzero.net ferg's tech blog: http://fergdawg.blogspot.com/