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OSPF Router ID conflict result in the routing table unstable

Publication Date:  2012-09-13 Views:  761 Downloads:  0

Issue Description

One site have four points A, B, C, D, each point have a NE80E. Four NE80E are interlinked by the interface of POS2.5G to build up a ring and the ring run OSPF protocol. Four POS interfaces were configured in one area. A is neighborhood with B and C. The faults are as follows:
1 When Ping IP address X.X.X.77 from NE80 of point A, the communication is up and down intermittently. (X.X.X.77 is the IP address of one interface of Point B NE80E and that interface connects directly with one 8750GE)  X.X.X.77 is the IP address which is connected from NE80E of Point B to the GE interface of 8750 directly
The routing information for the destination address X.X.X.77 of the NE80E Point B is learned from the router which connects directly with point B by OSPF. But when we check the routing table, found that this information disappear from time to time.
2 When we gather the router information in different period of time, the information is different in different period in the routing table of NE80E at point A.
The next hop of some router is NE80E of Point C instead of Point B, the router static and the router direct of point B and Point C appear at the NE80E of point C from time to time, the routing table is unstable.

Alarm Information


Handling Process

Change the router id of NE80E at point B and point C to un-collision, the routing table is stable, ping X.X.X.77. The problem is solved.

Root Cause

1 When we compare the gathered documents in two different period of time from points A, B, C, D, found that there are no differences. But it exits a huge mistake, which is the OSPF router id of point B and Point C collide with each other.
2 Because of the collision of router id, NE80E of point A refresh the routing table ceaselessly, sometime import the information from point B ,sometimes Point C, so result in the disappear of some information from time to time, when we ping some addresses, it works intermittently


The equipment in the same process OSPF, the router-id must be different.