Routing

Hi Experts

The multipath keyword will work for same EBGP routes comming from different AS?

Thanks

Hi,

by default if you want to use multipath command for load balance perpose with EBGP neighbors it have to be in same AS. If you want to load balance with different EBGP neighbors (different AS) you have to include multiple-as also

# set protocols bgp group ebgp multipath multiple-as

Thanks,

Mohamed Elhariry

JNCIE-M/T # 1059, CCNP & CCIP

Is it possible to load balance the traffic for the destination learning via different ISP and having different AS Path. For eg 1.1.1.1 is learning via 10.1.1.1 with AS path 100 200 300 and via 20.1.1.1 with AS path 100 200 300 400. 

It's alreday explained in this post.

If you want to load balance with different EBGP neighbors (different AS) you have to include multiple-as also

# set protocols bgp group ebgp multipath multiple-as

But in your case, there will be no load balancing as BGP will use path with the lowest as-path information which is learned via 10.1.1.1

 A path is considered a BGP equal-cost path (and will be used for forwarding) if a tie-break is performed after the previous step. All paths with the same neighboring AS, learned by a multipath-enabled BGP neighbor, are considered.

BGP multipath does not apply to paths that share the same MED-plus-IGP cost yet differ in IGP cost. Multipath path selection is based on the IGP cost metric, even if two paths have the same MED-plus-IGP cost.

https://www.juniper.net/documentation/en_US/junos12.3/topics/reference/general/routing-ptotocols-address-representation.html