I encountered a strange issue with routing and need your help.
You can refer to my topology for the description below:
- There are physical links between P1&P2 and D1&D2 only. There are two GRE logical tunnel between P1&D2 and P2&D1.
- There is a mesh iBGP among all routers.
- There is OSPF routing as internal routing protocol between routers
- There are two eBGP WAN links, only one used at a time.
The slowness issue happens when primary WAN link is shut down. User from outside accesses the web server via secondary WAN link and the response is very slow (30-40s to load a full page).
If I remove either P1 or D2 from OSPF routing (remove network command, no network 192.168.10(20).0 0.0.0.255 area 0), the response time for the web page becomes very fast (3-4s to load a full page).
I'm not sure what's wrong with the routing. Do you think what may cause an issue?