I'm not sure what problem that I'm facing but hoping any expert here could help.
Customer router, CE HQ site is connected to 2 ISP PE router , PE-a and PE-b using OSPF. PE-a act as active link and PE-b act as backup link.
All customer branches sites are using CE HQ as a gateway to internet.
Then, when active link down, all the branches cannot access to internet. Further check, default route cannot be learn from other branch.
When I checked the config at router PE-a, configuration for default-information originate for both OSPF and BGP were in place but NOT in router PE-b.
So while investigate the Active link PE-a (that was down at that time), default-information originate for both OSPF and BGP were added at router PE-b.
After that, customer branches site can access to internet.
When the Active PE-a router up, traffic still goes thru PE-b instead off router PE-a. Config default-information originate at PE-b had to be remove back so that traffic could flow back thru PE-a.
Do you guys have any idea why this happen?
Sample config at PE router
#####Active link (Router PE-a)########
router ospf 2627 vrf V739:ABC
redistribute bgp 24645 subnets
network 126.96.36.199 0.0.0.3 area 0
router bgp 24645
address-family ipv4 vrf V739:ABC
redistribute ospf 2627 vrf V739:ABC metric 1 match internal external 1 external 2
#####Backup link Router PE-b####
redistribute static subnets
network 188.8.131.52 0.0.0.3 area 0
redistribute ospf 2627 vrf V739:ABC match internal external 1 external 2