[c-nsp] Source address on BGP peering set up

[Jared Mauch]

> Anyone knows how BGP on a Cisco router choose source IP address for
> peering establishment if no "update-source" command is applied to
> neighbor? Is it only the primary IP address on the closest interface
> to neighbor?
> 
> For instance, let's say that you would like to set up a peering using
> a secondary IP address to between two directly-connected neighbors. Is
> it setting up loopbacks, static /32 routes and update-source on the
> neighbors' config the only way to do it?

	So, what you should b e able to do is this:

	"sh ip route "x.x.x.x" where x.x.x.x is the IP address
that is being peered with.

	it will use the IP from that interface to establish the
session.  If the host is 'connected', it will use an IP from the
"connected" secondary subnet.

	eg:

inteface FooTherNot0/0
 ip address 10.0.0.1 255.0.0.0
 ip address 192.168.0.1 255.255.0.0 secondary

	If you're peering with 10.0.0.2, it will use the 10.0.0.1
IP to source it.

	If you're peering with 192.168.0.2, it will use the 192.168.0.1
IP.

	If you're peering with an IP that is forwareded out this
interface, but is outside the scope of the 'connected' subnet,
it will use the primary ip to source ..

	- jared

-- 
Jared Mauch  | pgp key available via finger from jared at puck.nether.net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.