Compatible Systems 5.4 manual RIP Split Horizon

30 Chapter 2 - IP Routing & Bridging

•If Triggered is selected with this pull-down menu, the router will modify the standard RIP behavior for this interface to send RIP packets only when there has been an update to its routing table information, or when it has detected a change in the accessibility of the next hop router.

•If Periodic is selected with this pull-down menu, the router will use the standard RIP protocol, which sends RIP packets over the link every 30 seconds.

RIP Split Horizon

Normally, RIP uses a technique called split horizon to avoid routing loops and allow smaller update packets. This technique specifies that when the router sends a RIP update out a particular network interface, it should never include routing information acquired over that same interface.

There is a variation of the split horizon technique called “poison reverse” which specifies that all routes should be included in an update out a particular interface, but that the metric should be set to infinity for those routes acquired over that interface. One drawback is that routing update packet sizes will be increased when using poison reverse.

•If Split Horizon is selected with this pull-down menu, the router will apply the split horizon technique to routes being output over this inter- face.

•If No Split Horizon is selected with this pull-down menu, the router will include all routes in an output packet, regardless of which interface they were acquired over, and will use a normal metric.

•If Poison Reverse is selected with this pull-down menu, the router will include all routes in an output packet, but will set the metric to infinity for those routes which were acquired over this interface.

Output RIP - Input RIP

These flags control the behavior of RIP 1 and RIP 2 for this interface, allowing the router to selectively send RIP, receive RIP, or both. The default (assuming RIP 1 or RIP 2 is turned on in the Routing Protocol popup) is to both send and receive.

Directed Broadcast

This checkbox sets whether the interface will forward network-prefix-directed broadcasts. This is a security feature which can help prevent your network from being used as an intermediary in certain kinds of attacks which use ICMP echo traffic (pings) or UDP echo packets with fake (i.e., “spoofed”) source addresses to inundate a victim with erroneous traffic.