Comment 0 for bug 1582452
Revision history for this message
| vivekananda shenoy (vshenoy83) wrote 3.0 Controller : There has to be check against the AS path length when comparing ECMP routes in the case of federated clusters | #0 |
Something we saw during VES troubleshooting call today.
In 3.0 release whenever a Control node receives multiple BGP path for the same IP prefix from another Contrail controller or from the MX the bgp best path check is done by comparing local-preference and in case if one of the path has shorter AS-PATH length compared to the other one both are treated equal.
VES topo is as shown below. Cluster1 is getting 3 paths for IP address of a VM in cluster 2 and all 3 paths are installed in the agent routing table although the direct EBGP path from cluster 2 has AS-PATH-LEN of 1. This is creating issues w.r.t ARP resolution for the IP address of VM in cluster 2, as the ARP is getting resolved to vhost0 MAC address of the compute node in cluster 2. I am opening a separate PR for that.
Regards,
Vivek
| |
+----------+ MX1 +-------------+
| | | |
| +------+ |
| +------+ |
| | | |
| | MX2 | |
EBGP | +------+ +--------+ |
| | +------+ | |
| | | |
| | | |
| |EBGP EBGP | |EBGP
| | | |
| | | |
+-----+---+-+ ++----+------+
| | | |
| | EBGP | |
| Cluster1+
| | | |
+-----------+ +------------+