Neighbors on the Same Network

It is an error to configure two neighbors to serve the same logical local network (network and service).

Since no gain could possibly result from forwarding messages from a network to the same network, it might seem that this error is rather rare. Nonetheless, in actual practice this error occurs rather frequently as an oversight.

Consider the situation in Erroneous Neighbors on the Same Network. In the desired outcome, neighbors on computers gemini and taurus exchange messages on UDP service 7500 between the two networks, Castor.star.com and Pollux.star.com. Because computer gemini has two network interfaces, the administrator attempts to limit rvrd operation to only Castor.star.com. Nonetheless, the routing daemon on gemini still receives messages from Pollux.star.com through its other interface (to understand the reason for this behavior, see Limitation on Computers with Multiple Network Interfaces). Because the two neighbors both serve the same network, Pollux.star.com, erroneous behavior results.

If gemini had only one network interface, Castor.star.com, the routing daemons would operate correctly.

When the routing daemon detects a topology error of this kind, it outputs an error message. Administrators must correct this situation immediately.

Figure 66: Erroneous Neighbors on the Same Network