Nortel BCM 3.7, Manual

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N0008589 3.3
Open Shortest Path First (OSPF)
Open Shortest Path First protocol bases its path descriptions on “link states” that take into account
additional network information. OSPF also lets the user assign cost metrics to a given host router
so that some paths are given preference. OSPF supports a variable network subnet mask so that a
network can be subdivided into areas. For information on how to select OSPF as your routing
protocol, see
“Configuring OSPF parameters on a network interface” on page 716 .
The implementation of OSPF on Business Communications Manager is designed to operate as an
edge router in an OSPF intranet, or as a backup router in a small network. Do not configure
Business Communications Manager for multiple OSPF areas.
IP routing protocol precedence
The followings table shows the Business Communications Manager IP routing protocols and the
precedence order when conflicting or redundant routes occur.
Note: Business Communications Manager is an edge router and will not act as a router
spanning RIP and OSPF routing networks (RIP or OSPF redistribution).
Warning: Because OSPF is a “link-state” based routing protocol, you must not use
OSPF on dial-on-demand interfaces. Frequent link status (between “up” and “down”) may
cause the protocol to become unstable.
Table 200 IP routing protocol precedence
Precedence IP Routing Protocols
1. Static Routing
2. OSPF RIP v1 and v2