Intel 480T, User Manual

Page: 169 / 367

C H A P T E R 1 0 IP Unicast Routing
167
Populating the Routing Table
The switch maintains an IP routing table for both network routes
and host routes. The table is populated from the following sources:
• Dynamically, by way of routing protocol packets or by ICMP
redirects exchanged with other routers
• Statically, by way of routes entered by the administrator
- Default routes, configured by the administrator
- Locally, by way of interface addresses assigned to the system
- By other static routes, as configured by the administrator
If you define a default route, and subsequently delete the VLAN on
the subnet associated with the default route, the invalid default route
entry remains. You must manually delete the configured default
route.
Dynamic Routes
Dynamic routes are typically learned by way of RIP or OSPF.
Routers that use RIP or OSPF exchange information in their routing
tables in the form of advertisements. Using dynamic routes, the
routing table contains only networks that are reachable.
Dynamic routes are aged out of the table when an update for the
network is not received for a period of time, as determined by the
routing protocol.
Static Routes
Static routes are manually entered into the routing table. Static
routes are used to reach networks not advertised by routers.
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 one of the following
commands:
[enable | disable] rip export static
[enable | disable] ospf export static
The default setting is enabled. Static routes are never aged out of the
routing table.