Article ID: 195640 - View products that this article applies to.
This article was previously published under Q195640
When RIP is set with all the default settings, including the Advanced settings of Split Horizon with Poison Reverse, the RIP update will occur for both bound IP addresses but with an incorrect hop count (or metric) of 16. Because it advertises the metrics as 16, no other routers will know that this computer is the router between those two subnets and, thus, the two subnets will be unable to communicate with each other.
This problem occurs on a computer that is configured to use RIP and that has a single network adapter configured for multiple IP addresses on different subnets.
RRAS assigns an incorrect metric in outbound RIP requests when two IP addresses are bound to the same network card.
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:
Microsoft has confirmed this to be a problem in Windows NT version 4.0. This problem was first corrected in Windows NT version 4.0 Service Pack 5.
Split Horizon with Poison Reverse:
Split horizon with poison reverse improves RIP convergence over simple split horizon by advertising all network IDs, but those network IDs learned in a given directions are advertised with a metric of 16, indicating that the network is unavailable. Poison reverse has no benefit beyond split horizon in a single path internetwork. However, in a multipath internetwork, split horizon with poison reverse greatly reduces count to infinity and routing loops.
This behavior is described in RFC 1058, "Routing Information Protocol".