BGP local preference consideration

[acbennyma]

Dear all,

Requirement.

1) For HGC related AS IP, first will choose HGC path 1G path to go, in case HGC 1G link fail, will use HGC 100M link to go, once ALL two HGC lnks fail, Final step is choose HKIX link

2) Out of HGC related AS IP, first will choose HKIX 1G path to go, in case HKIX 1G link fail, will use HKIX 100M link to go, once All two HKIX lnks fail, Final step is choose HGC link

Does the attach diagram and configuration can acheive this behaviour?

[acbennyma]

Dear all,

I review the configuration again and think attach configuration is more suitable. Can I right ? Please advise.

[Edison Ortiz]

This configuration looks better in terms of the failure scenario.

You still have to fix the as-path list

[Edison Ortiz]

Your AS Path list is incorrect, it should be:

ip as-path access-list 80 permit 9304$

ip as-path access-list 80 permit 10032$

ip as-path access-list 80 permit 10118$

ip as-path access-list 80 permit 45590$

local preference will dictate the best route out of your iBGP mesh.

When all links are up, Router 2 will use its 1Gbps link towards HGC for networks

with the AS Paths mentioned above.

If you lose the 1Gbps link, the next best local preference will be Router 1's 100Mbps to HGC.

However, if that link fails as well there is a tie between the 2 remaining links

as they all have local preference set to 500.

Your HKIX route-map has a match for as-path 81 but that as-path list has a deny for the above ASes.

Therefore, sequence 20 will set the local preference on both routers.

Based on the diagram and config provided, we can't tell how the return traffic will use the links.

Local preference will help you how the traffic exits the AS, not how it enters the AS.

You may need to use AS-PATH prepend if you want to influence how traffic enter your AS w/o

changing the configuration on the remote routers.