BGP next hop

Ondrej Zajicek santiago at
Wed May 9 15:36:59 CEST 2018

On Wed, May 09, 2018 at 07:38:31AM +0000, Arvin Gan wrote:
> Hi all,
>    I notice below description in user guide, my understand is source
> address mainly used for BGP session for TCP connection ,don't understand
> why this source is also used as next_hop_addr calculation.


Generally, BGP speaker have to select reasonable bgp_next_hop address
from its IP addresses. BIRD uses by default the source address of BGP
session if applicable (like matching AF or ext_next_hop), otherwise it
takes preferred IPv4 or IPv6 address of the same iface where is the
source address. Or could be explicitly configured by 'next hop address'
option. See function bgp_channel_start() for details.

Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3,
"To err is human -- to blame it on a computer is even more so."

More information about the Bird-users mailing list