eBGP running over GRE on Brocade Vyatta OS

On Softlayer, Vyatta 6.x Subscription Edition (64 bit) is offered. This subscription version Vyatta OS is provided by Brocade.

The latest version of Brocade Vyatta OS is VSE6.7R5S1.

Today, I just met another “difference” between Vyatta OS and other traditional vendors like Cisco and Juniper. The difference is on eBGP over GRE tunnel.

Like Cisco and Juniper, eBGP session is established between two GRE end points on Vyatta OS.

_{Vvyatta@vyatta:~$ show ip bgp summary}

_{BGP router identifier 172.16.100.2, local AS number 103}

_{BGP table version is 73}

_{3 BGP AS-PATH entries}

_{0 BGP community entries}

_{Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd}

_{172.16.100.1 4 100 143 141 73 0 0 00:52:33 0}

_{172.16.100.5 4 100 148 147 73 0 0 01:11:53 0}

However, i cant see any BGP routing in the routing table.

_{vyatta@vyatta:~$ show ip route}

_{Codes: K – kernel, C – connected, S – static, R – RIP, B – BGP}

_{O – OSPF, IA – OSPF inter area}

_{N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2}

_{E1 – OSPF external type 1, E2 – OSPF external type 2}

_{i – IS-IS, L1 – IS-IS level-1, L2 – IS-IS level-2, ia – IS-IS inter area}

_{> – selected route, * – FIB route, p – stale info}

_{C *> 10.1.1.0/24 is directly connected, eth0}

_{C *> 127.0.0.0/8 is directly connected, lo}

_{C *> 172.16.32.0/24 is directly connected, lo}

_{C *> 172.16.100.0/30 is directly connected, tun1}

_{C *> 172.16.100.4/30 is directly connected, tun2}

_{C *> 192.168.56.0/24 is directly connected, eth1}

_{C *> 192.168.100.0/24 is directly connected, lo}

I can see the BGP routing has been advertised by remote BGP peer and received by the local BGP router.

_{vyatta@vyatta:~$ show ip bgp neighbors 172.16.100.5 received-routes}

_{BGP table version is 70, local router ID is 172.16.100.2}

_{Status codes: s suppressed, d damped, h history, * valid, > best, i – internal}

_{Origin codes: i – IGP, e – EGP, ? – incomplete}

_{Network Next Hop Metric LocPrf Weight Path}

_{*> 172.16.31.0/24 172.16.100.5 0 100 i}

_{*> 192.168.107.0 172.16.100.5 0 100 i}

_{*> 192.168.108.0 172.16.100.5 0 100 100 100 100 i}

After performed a BGP debug, I see the below:

_{Mar 6 03:13:53 vyatta BGP[2472]: BGP: 172.16.100.1-Outgoing [RIB] Update: Prefix 172.16.31.0/24 denied due to non-connected next-hop;}

_{Mar 6 03:13:53 vyatta BGP[2472]: BGP: 172.16.100.1-Outgoing [RIB] Update: Prefix 192.168.107.0/24 denied due to non-connected next-hop;}

Interesting, Vyatta OS consider GRE tunnel as non-connected network which is different from Cisco/Juniper. More interestingly, the BGP neighbor session is allowed to be established but it denies the BGP routing injection.

Anyway, I add the following in my eBGP configuration. Then everything is OK! Job Done!

_{set protocols bgp 103 neighbor 172.16.100.1 ebgp-multihop ‘2’}

_{set protocols bgp 103 neighbor 172.16.100.5 ebgp-multihop ‘2’}

Tips: how to perform BGP debug on Vyatta

#monitor protocol bgp enable events

#monitor protocol bgp enable updates

Update: Brocade just confirmed the above BGP issue which i met is a Bug. They will fix it ASAP.