Hi, Is OpenBGPD capable of inserting equal cost multi-path routes into the kernel FIB like OpenOSPFD can?
I have equal cost routes being received into OpenOSPFD's RIB from two different OSPF ASBR neighbors, for accessing the same IXP network to which we are connected. These two multi-path routes are inserted into the Kernel FIB fine. If I ping various routers on the IXP network I can see that multi-path is being used and a different ASBR neighbor is used for each IP etc.. Great :) [LIVE]root@mg131:~# ospfctl show rib | grep 5.57.80 5.57.80.0/22 185.25.30.2 Type 1 ext Network 21 01w1d09h 5.57.80.0/22 185.25.30.1 Type 1 ext Network 21 01w0d04h [LIVE]root@mg131:~# netstat -rn | grep 5.57.80 5.57.80/22 185.25.30.2 UGP 0 42 - 32 vlan202 5.57.80/22 185.25.30.1 UGP 0 77 - 32 vlan202 I therefore of course also have equal cost routes being received into OpenBGPD's RIB from the two different iBGP peers (the same two ASBR neighbors as above), for all the networks received via our IXP BGP peerings. OpenBGPd by default only selects one path to the remote networks, the nexthop in the IXP network for the path is translated into a directly connected nexthop (using the OSPF routes for the IXP network). [LIVE]root@mg131:~# bgpctl show rib | more flags: * = Valid, > = Selected, I = via IBGP, A = Announced, S = Stale origin: i = IGP, e = EGP, ? = Incomplete flags destination gateway lpref med aspath origin I*> 1.0.0.0/24 5.57.80.136 1000 0 15169 i I* 1.0.0.0/24 5.57.80.136 1000 0 15169 i I*> 1.0.4.0/24 5.57.80.128 100 1 6939 7545 56203 i I* 1.0.4.0/24 5.57.80.128 100 1 6939 7545 56203 i I*> 1.0.5.0/24 5.57.80.128 100 1 6939 7545 56203 i I* 1.0.5.0/24 5.57.80.128 100 1 6939 7545 56203 i . . [LIVE]root@mg1311:~# netstat -rn | more Routing tables Internet: Destination Gateway Flags Refs Use Mtu Prio Iface 1.0.0/24 185.25.30.2 UG 0 0 - 48 vlan2302 1.0.4/24 185.25.30.2 UG 0 0 - 48 vlan2302 1.0.5/24 185.25.30.2 UG 0 0 - 48 vlan2302 . . However it always chooses the same directly connected ASBR for every route during the next-hop translation step and no load balancing is achieved. :( Even if I use 'next-hop-self' on the ASBR's to remove the nexthop translation step, the same ASBR is always chosen (due to BGP best path selection always matching for each route). I also don't want to use next-hop-self anyway as that would *destroy* convergence times should an ASBR be unavailable, as in the absence of BFD it would be relying on BGP long timers to change the route, instead of having OSPF's fast convergence to change the next-hop in less than a second. From my understanding the only options are; 1) Randomize the directly connected nexthop used during in the next-hop translation step. 2) Use next-hop-self on the ASBR's to insert two routes into the RIB with different next-hops (one for each ASBR) (requiring BFD for BGP to not destroy convergence), and also enable BGP multi-hop (http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13753-25.html#bgpmpath) to insert both RIB routes into the FIB, so the kernel can perform equal-cost multi-path routing. Thanks for your time and for reading. Cheers, Andy. /**/
