Conflicted Router ID Leads to OSPF Route Flapping on the Entire Network

Publication Date:  2012-07-27 Views:  100 Downloads:  0
Issue Description
Networking:
MOTO---------NE80E(ar1)--------NE80E(ar2) 
                                  | 
                        NE80E(ar3)
Ping the device of MOTO from the collector attached to AR2 and AR3 and packet loss occurred frequently. View the OSPF route count and route flapping occurred repeatedly. 
 
Alarm Information
Null
Handling Process
According to the customer, the network ran normally before, route flapping started after configurations were refreshed once.
1. Because configuration refreshing did not involve the device of MOTO, the problem might occur on our device.
2. View the configurations on each router and AR3 was not configured with a router ID, which adopted the address of the loopback interface by default. However, the address of the loopback interface conflicted with the router id of AR2, so two ARs used the same router id. In this case, OSPF LSA of the upper-layer router was repeatedly refreshed, leading to OSPF route flapping and then packet loss.
3. Configure a router ID for AR3 to avoid conflict and everything returned to normal. 
 
Root Cause
1. The device of MOTO cannot receive ping packets from our device continuously.
2. Incorrect configurations on AR2 and AR3 lead to repeated route refreshing.
3. Board hardware is faulty. 
 
Suggestions
Null

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