
Customizing OSPF Services
114065 Rev. A 5-7
In Figure 5-1, for example, routers R1 and R2 are boundary routers that use BGP
and EGP to connect the backbone to external ASs. R7 in Area 0.0.0.1 is also a
boundary router, connecting the area to an external RIP network. R14 in Area
0.0.0.3 connects the area to an external AS via BGP.
For further information and instructions, see “Configuring a Boundary Router” on
page 5-25.
OSPF Implementation Notes
This section provides some suggestions to help you configure your OSPF
network. The Bay Networks OSPF implementation does not restrict you to these
suggestions, but we are providing them as guidelines.
• Keep the same password throughout an area, or even throughout the entire
OSPF AS, if possible.
• Use the default timers, unless you are running 9.6-KB sync lines. In this case,
double the default timers on both ends of the link.
• Use address ranges if your network is a subnetted network.
• Keep all subnets within one area. If you cross areas, you cannot configure
summaries.
• Make sure the AS Boundary Router function is enabled if the router has any
non-OSPF interfaces and if you want that information propagated.
• You must configure virtual links for each area border router that does not
reside within or directly interface to the backbone. Every area border router
must have a configured path to the backbone.
• Rather than just a hop count, OSPF considers the cost of a path when
choosing the best path. Each interface, however, is assigned the default cost 1
for the path to which it interfaces. If you have a preferred path, you must edit
the Metric Cost parameter for your interfaces. You will need to assign a
higher metric cost for those paths which are not preferred paths.
• If you have any devices in your network running OSPF, and are now adding a
Bay Networks router, you must make sure that the router’s timer values
coincide with the timers in your other devices. Determine the timer values of
the other devices, and change the router’s timer values to match them.
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