bgp issue with default route

[csc010854800]

i have two default static routes at R5 towards r3 and r4 .

two subnets are advertised to ISP 1 and twao subnets are advertised to ISP 2 .

these subnets are the lan pools on R5 .

Now the problem is , packets takes the default route randomly eg from R3 and goes to R1  and then to ISP 2 but the packets return from ISP 1 ,

it creates problem in some of the applications.

diagram is attched , can anyone suggest some solution.

for reverse route , from R1 and R2 toward R5 , i  have run OSPF .

[Edison Ortiz]

You didn't attach any diagram but ideally you want symmetrical routing with BGP. You can accomplish this by using AS_Prepend towards the ISP to advertise these subnets with less preference. With AS_Prepend traffic coming from the outside will use the path with the shortest AS info.

For traffic leaving your network, you can use local_pref (if you have an iBGP mesh between edge devices).

Regards,

Edison

[Marwan ALshawi]

Also you can refer tonthe below link for some config examples to be applied such as the suggestion from Edison above

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml

Hope this help