Load Sharing When Multihomed to Two ISPs Through Multiple Local Routers

[Halil.Zakaria]

Hello,

thank you in advance for your precious support.

I have a question about s particular BGP multihoming scenario example been published on the link below:

http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13762-40.html

The outbound policy stipulates last rule stipulates that:

• Traffic that is destined to AS 300 goes through the R1-ISP(A) link.

• Traffic that is destined to AS 400 goes through the R2-ISP(B) link.

what I understand from this is that an inbound filter 

sets originated routes from AS 300 in R1 to higher local preference than R2 

sets originated routes from AS 400 in R2 to higher local preference than R1

the route-map is like this:

in R2:

route-map AS-400-INCOMING permit 10 
match as-path 1 
set local-preference 150 

in R1:

route-map AS-300-INCOMING permit 10 
match as-path 1 
set local-preference 200

now let jump to the problem, as stated by the last rule of outbound policy:

If the R1-ISP(A) link fails, all traffic should go through the R2-ISP(B) link.

but when I shutdown bgp between R1 and AS300 ISP  router, network  30.30.30.0/24 was  not advertised from AS400 router (no failover happened).

am I missing something here.

thank you

[Halil.Zakaria]

Hello,

I've noticed that route-map AS-300-INCOMING and AS-400-INCOMING in R1 and R2 respectively

are allowing only AS-300 originated routes in R1 and AS400 originated routes in R2 exclusively and filters anything else

route-map AS-X00-INCOMING permit 10
 match as-path 1
 set local-preference (Higher than 100)
!

I've added these statements to allow AS400 originated routes in R1 and AS300 originated routes in R2

in R1:

ip as-path access-list 2 permit ^400$

route-map AS-400-INCOMING permit 20

match as-path 2

exit

in R2

ip as-path access-list 2 permit ^300$

route-map AS-300-INCOMING permit 20

match as-path 2

exit

but still no failover, is it because I have numbered the acl and as-path acl with same number ?