Host conflict window always pops up, and cleaning routing table doesn't help.
Host conflict is a normal issue happening in I/NET. It is usually caused by the duplicated host ID setting on different servers, or an engineer laptop is inserted into the network with the same host ID setting with some server. And the routing table will be messed up since all the IP releated information will be recorded in the routing table and it will be distributed to all the network devices, including all the servers and NPRs. The usual solution is to clear all the routing tables on all the network devices, . Refer to Lessons Learned Article LL#12759 about how to clear the routing tables.
But if the routing table is cross referred, like Server 1 adding NPR 1 and NPR 2 as reference hosts, while NPR1 adding Server 1 and NPR 2 as reference host, the routing table will never be cleaned out since when you clean the routing table for Server 1, NPR1 and NPR 2 will still try to send their wrong routing table to Server 1. Unless all the network devices are disconnected and the routing tables are cleaned one by one, or disable the 50069 port for the whole network, which is used by the communication between network devices, there is no other way to clean them out. And these two method are not applicable sometimes.
If the routing table can be managed well, such kind of issue will never happen. The best practice on adding reference host and creating routing table is:
1. On the servers: Choose one server as the master reference host. All the other servers add this server as reference host. Don't add NPR as reference host. All the NPRs can be added into the master server by clicking on the NPR button in I/NET configuration and added one by one manually. By this way, the master server can build its own routing table without impacted by other devices. And this one is the only routing table in the whole network.
2. On NPRs. If NPR doesn't need to talk to other NPRs, like transfering indirect points, there is no need to add reference host for NPR. If indirect points are needed, just add the master server as the reference host. Then this NPR will be able to see all the other NPRs based on the routing table on the master server.
3. If the master server is not equipped with UPS, or not always promises to be online, another master NPR can be chosen as a secondary reference host. Add this NPR as a reference host to all the servers and other NPRs.
Under this senario. if the routing table needs to be cleaned, only the master server and the secondary reference host need to be cleaned. It will be more easier to clean all the routing table and get rid of the host conflict error.