1. Topology: Two NE80Es and J M40 establish EBGP neighbor relation. IBGP relation is established between two NE80Es and OSPF is enabled. M40 advertises default route through BGP. NE80E advertises default route non-forcibly through OSPF, the topology is as follows:
2. Phenomenon: The next-hop of default route on NE80E-A is M40-A, but the next-hop of default route on NE80E-B is NE80E-A, not M40-B. Two egresses has one uplink.
1. Check configuration and BGP relation between two NE80Es and opposite M40 BGP is normally established.
2. BGP rotuing table of NE80-B has route whose next-hop is M40-B. But the default route of the table is sent by OSPF of NE80E-A.
3. When the routing table chooses route, it first compares protocol priority. O_ASE priority of OSPF is 150 and EBGP priority is 255. There are two default routes and the route with higher priority is chosen.
4. VRP5.1 version can solve the problem by changing the priority of BGP protocol.
5. There are two ways to change configuration:
A. Change bgp preference and the command is as follows:
preference EBGP IBGP LOCAL
B. Change BGP preference according to IP prefix, the configuration is as follows:
preference route-policy SetDefaultRoutePref
list of configuring prefix:
ip ip-prefix SetDefaultRoutePref index 1 permit 0.0.0.0 0
Confiugre policy route:
route-policy SetDefaultRoutePref permit node 1
if-match ip-prefix SetDefaultRoutePref
apply preference 100 //Change EBGP priority as 100.
6. Through the configuration above the default route of two NE80Es points to opposite M40 and double-uplink forms.
1. BGP neighbor relation is not established.
2. Route propagation is problematic.
3. The priority of routing protocol.
1. For the choice of route priority, longest match is used. If it is the same, compare protocol priority.
2. The change of BGP priority X does not support the use of peer ×.×.×.× route-policy.