Lucent Technologies 6000 - Manual (Page 397)

Configuring IP Routing
Configuring WAN interfaces
MAX 6000/3000 Network Configuration Guide 9-33
Assigning metrics and preferences
Connection profiles often represent switched connections, which have an initial cost that you
avoid if you use a nailed-up link to the same destination. To favor nailed-up links, you can
assign a higher metric to switched connections than to any of the nailed-up links to the same
destination.
Each connection represents a static route, which has a default preference of 100. (For other
preferences, see “Route preferences and metrics on a MAX unit” on page 9-56.) For each
connection, you can fine-tune the route preference or assign a completely different preference.
Note: In the Connection profile’s IP Options subprofile, you can set the DownMetric and
DownPreference parameters to assign different metrics or preferences to routes on the basis of
whether the route is in use or is down. You can direct the unit to use active routes, if available,
rather than choose routes that are down.
Configuring RIP on a WAN interface
In the Connection profile’s IP Options subprofile, you can set the RIP parameter to specify an
IP interface to send RIP updates, receive RIP updates, or both.
Lucent recommends that you run RIP version 2 (RIP-v2) if possible. Lucent does not
recommend running RIP-v2 and RIP-v1 on the same network in such a way that the routers
receive each other’s advertisements. RIP-v1 does not propagate subnet mask information. It
assumes the default mask for the network’s class. RIP-v2 propagates subnet masks explicitly.
Running the two versions on the same network can result in RIP-v1 guesses overriding
accurate subnet information obtained through RIP-v2.
In the Connection profile’s IP Options subprofile, the Private parameter specifies whether the
unit discloses the existence of the route when queried by RIP or another routing protocol. The
unit uses private routes internally. They are not advertised.
IP Direct configuration
An IP Direct configuration allows IP packets received from an incoming connection to bypass
the routing and bridging tables and be redirected to the next-hop router, which must be on the
same network as the MAX. Outgoing packets are routed as usual. They are not affected by the
IP Direct configuration.
To enable IP Direct, you set the IP Direct parameter in the Connection profile’s Session
Options to specify the IP address of the next-hop destination.
Note: Typically, you configure IP Direct connections with RIP turned off. If you set the IP
Direct configuration with RIP set to receive, the MAX unit forwards all RIP updates to the
specified address. Typically, this is not desirable, because RIP updates are designed to be
stored locally by the IP router (in this case, the MAX).