I tried some additional debugging with this setup :

(Note : All interfaces are tap interfaces)

eth-0 (10.0.1.11/24) - ospf and bgp configured

Result : OSPF is up and running, BGP is in established state

Changed OSPF to be on eth-1. It stays in alone state. (Packet capture shows hello packets being received from neighbor. Neighbor adds us(bird) and changes to init state but bird seems to just not receive packets . Doing a 'netstat -an' , the receive and send queue are empty inspite of packets being received on that interface.

Then when we change eth-0 to other subnet (10.0.3.11/24) , OSPF on eth-1 immediately comes up , bgp on eth-1 is also in established state. But BGP on eth-0 times out.

I think the kernel does not like the interfaces in same subnet ? (just a guess here).

In my device protocol , i am just scanning interfaces every 10 seconds. I have a custom forwarding plane and so, dont use kernel protocol( that does not seem to be the issue here though).

Thanks,

On Sat, Oct 10, 2015 at 6:15 AM, Ondrej Zajicek <santiago@crfreenet.org> wrote:

On Thu, Oct 08, 2015 at 06:48:19PM -0400, Jigar Mehta wrote:
> Hi, I wanted some help regarding a problem I was seeing when i had multiple
> interfaces with same ip address . I have multiple routing domains setup so
> i have valid cases to have same ip address on different interfaces (so i
> have seperate routing tables for each instance). When I do a show ospf
> interface for each ospf protocol instance, it seems to correctly dump the
> interface . When I did a packet capture, it shows incoming/outgoing hello
> packets, but when I enabled debug, i can see that it never prints a "hello
> packet received" message(but prints "hello packet sent") although, i can
> see the peer sending ospf hello packets.
> This seems to be a problem with only one instance and not both.

Hi

I don't know. I just tested it, works for me. Does the other side see
sent hello packets? (Should be in Init state.) If you disable the other
interface with the same address, does the problematic iface start to work?

--
Elen sila lumenn' omentielvo

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

Jigar Mehta