Compatible Systems 5.4 - Manual (Page 36)

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.