S
UMMIT
S
WITCH
I
NSTALLATION
AND
U
SER
G
UIDE
9-3
O
VERVIEW
OF
IP U
NICAST
R
OUTING
D
YNAMIC
R
OUTES
Dynamic routes are typically learned by way of RIP. Routers that use 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.
S
TATIC
R
OUTES
Static routes are manually entered into the routing table. Static routes are used to reach
networks not advertised by routers. You can conÞgure up to 64 static unicast routes on
the Summit.
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,
using the following command:
[enable | disable] rip exportstatic
The default setting is enabled. Static routes are never aged out of the routing table.
M
ULTIPLE
R
OUTES
When there are multiple, conßicting 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 criterion (in the order speciÞed):
¥
Directly attached network interfaces
¥
ICMP redirects (refer to
Table 9-4
)
¥
Static routes
¥
RIP
¥
Directly attached network interfaces that are not active.
You can also conÞgure
black-hole
routesÑtrafÞc to these destinations is silently dropped.
SUMMIT.BK Page 3 Thursday, September 25, 1997 12:33 PM
