City A: NE80 A----provincial network device A from Vendor C----MAN outbound interface
City B: NE80 B----provincial network device B from Vendor C----MAN outbound interface
The version of the NE80 was VRP3.10. The NE80E was connected to the device from Vendor C in BGP mode and received the default routes delivered by the latter and at the same time, delivered default routes in OSPF unforcible mode.
Phenomenon: Because the upstream fault of device A from Vendor C occurred and services under city A could not go out from the MAN, traffic needed to be dredged between NE80 A and NE80 B and OSPF neighbor relationship was established between them.
Fault: Services under NE 80 B were also interrupted.
NE80 VRP3.10 calculates the default routes delivered by the routers in the process and cannot modify the BGP priority. Therefore, a static default route to the device from Vendor C needs to be configured. In this manner, services are recovered because of higher priority of the static default route.
NE80 B VRP3.1 calculated the default routes delivered by NE80 A, so NE80 B learned the default routes of NE80 A. The priority of the default routes of OSPF was higher than that of the default routes delivered by EBGP, and therefore services were interrupted.
VRP3.1 did not support the modification of the priority of BGP.