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bgp issue with default route

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 .

2 REPLIES
Hall of Fame Super Bronze

bgp issue with default route

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

bgp issue with default route

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

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