3Com 3800 - Manual (Page 115)

Overview of IP Unicast Routing 8-3
Dynamic Routes
Dynamic routes are typically learned by way of RIP. Routers using RIP
exchange information in their routing tables in the form of RIP
advertisements. Using dynamic routes, the routing table contains only
networks that are reachable.
Dynamic routes are aged out of the table when a RIP update for the
network is not received for a period of time.
Static Routes
Static routes are manually entered into the routing table. Static routes
are used to reach networks not advertised by routers. You can
configure up to 64 static unicast routes on the Switch 3800.
Static routes can also be used for security reasons, to control which
routes you want advertised by the router. You can decide if you want
all static routes to be advertised by using the following command:
[enable | disable] rip exportstatic
The default setting is enabled. Static routes are never aged out of the
routing table.
Multiple Routes
When there are multiple, conflicting choices of a route to a particular
destination, the router picks the route with the longest matching
network mask. If these are still equal, the router picks the route using
the following criteria (in the order specified):
■
Directly attached network interfaces
■
ICMP redirects (refer to Table 8-4)
■
Static routes
■
RIP
■
Directly attached network interfaces that are not active.
You can also configure blackhole routes—traffic to these destinations
is silently dropped.
SW3800.BK Page 3 Tuesday, May 5, 1998 5:20 PM