Load Sharing with different as-path length

[Gailardia]

I know that we can use 'bgp bestpath as-path multipath-relax' for multi-homed solution with same as-path length.

Is there anyway to have multi-path for different path length.

Such as:

Network               Next Hop           Metric LocPrf Weight    Path
* 10.80.17.0/24  172.16.2.65         0                     0        65002 i
*>                         172.16.1.1                                0        65001 65002 65002 i

 (Show from AS65000)

Requirement is. Because provider issues, we cannot provide same 2 providers for AS65002 as other branches. So we need to use AS65000 as hub to route to other branches.

For each branches, I can use prepend to utilize both links as multipath. But I cannot use it at AS65000 because it'll effect these paths.

[Terence Payet]

Hi,

You can use "bgp bestpath as-path ignore".

Regards,

Terence

[Gailardia]

Already tested that solution.
Not seem to work for Multi-path.

When I apply 'bgp always-compare-med', it still only choose 1 best path.

Please note that I already added maximum-path 5

[Terence Payet]

Hi,

You can try the below. It is a bit dirty, but it should work:

route-map AS_PATH permit 10

set as_path prepend 65002 65002

router bgp xxxxx

neighbor 172.16.2.65 route-map AS_PATH in

bgp bestpath as-path multipath-relax

maximum-path 2

The above route-map will allow you to get the same AS PATH length by doing prepending and when use in conjunction with "bgp bestpath as-path multipath-relax" you should achieve load sharing.

Please rate helpful posts.

[Gailardia]

My main problem for prepend in was, it effect other route advertisement as well. There some routes that had to pass through this router.
This router acted like hub of all branches network. I can manage to balancing other branches as-path length but if I prepend something in this router. Other branch will not load sharing.

That's why I tried to find solution to balancing routes without effect routes advertisement.

I saw command 'bgp multipath as-path ignore', but that can only achieve only in IOS XR :(

[Terence Payet]

Hi,

Will be great if you can share the BGP topology in terms of AS-PATH between the hub and the spokes so that we can help further.

As for the 'bgp multipath as-path ignore' it is available on older platforms, but it is a hidden command so basically you need to type the whole thing in.

[Gailardia]

'bgp multipath as-path ignore'

I typed the whole thing, but not worked.

 

What I show is from router AS65000.

Requirement is. Because provider issues, we cannot provide same 2 providers for AS65002 as other branches. So we need to use AS65000 as hub to route to other branches.

For each branches, I can use prepend to utilize both links as multipath. But I cannot use it at AS65000 because it'll effect these paths.

[Gailardia]

Any help?

[sbhadrav@cisco.com]

It states that Loadbalancing between two different AS is not possible unlike Loadbalancing between same AS. The solution is to configure weight parameter such a way that routes received from ISP-1 should be higher than 0 for prefixes 0-128 and configure weight parameter such a way that routes received from ISP-2 should be higher than 0 for prefixes 128-254.