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Foundry NetIron M2404C and M2404F Metro Access Switches
Configuring IP Unicast Routing
The switches provide full Layer-3 IP unicast routing. They exchange routing information with
other routers on the network using the Open Shortest Path First (OSPF) Protocol (for additional
information on OSPF, refer to the chapter Configuring Advanced Routing Information). When
enabled on a given device, the routing protocols dynamically update the routing table in order to
ensure proper routing.
Overview
Creating an IP Interface
A router IP interface is the holder of an IP address. As the user creates VLANs with IP addresses
belonging to different IP subnets, the user can also choose the route between the VLANs. Both the
VLAN switching and IP routing function occur within the device. Each IP address and mask
assigned to a VLAN must represent a unique IP subnet. However, the user can configure the same
IP address and subnet on different VLANs (up to 20 VLANs). The binding between VLANs and
IP addresses (IP Interfaces) is done by using the rif command in VLAN Configuration mode.
NOTE
Populating the Routing Table
A Foundry Networks router maintains an IP routing table for both network routes and host routes.
The table is populated from the following sources:
• Dynamic routes, typically learned from routing protocol packets;
• Static routes, manually entered by the administrator. These include
Default routes, configured by the administrator;
Local routes, of IP interface addresses assigned to the system;
Other static routes, as configured by the administrator.
Dynamic Routes
Dynamic routes are typically learned by the routing protocol OSPF. Routers that use the routing
protocols exchange information in their routing tables by advertising. Using dynamic routes, the
routing table contains only networks that are accessible. Dynamic routes are deleted from the table
when either of the following occurs:
• An update for the network is not received for a period of time that is determined by the routing
protocol (i.e., the dynamic route is aged out of the table).
• A neighbor sends a command to delete the dynamic routes advertised via OSPF by setting the
route aging time to the maximum (3600 seconds by default) and flooding the LSA to the
advertiser neighbors.
Configuring IP Unicast Routing
The user can disable the routing (IP forwarding) between the IP interfaces
(subnets) on the device by using the ip-forward command in IP Table Configuration
mode.
© 2008 Foundry Networks, Inc.
Configuring Routing Information (Rev. 03)
Page 3 of 48
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