3Com 4007, Руководство по внедрению, Страница: 390 / 684

390 C
HAPTER
16: IP R
OUTING
Setting Up RIP
Routing Policies
To configure a routing policy, follow these general steps:
1 Establish an Export policy that controls the advertisement of routes
through RIP, regardless of the source from which the route is learned.
2 Establish an Import policy that accepts or refuses to accept information
on routes learned by RIP from a trusted neighbor.
3
To control the reporting of routes that are learned from specific sources,
establish the following policies:
■
Export policy for routes learned from OSPF
■
Static policy for reporting static (user-configured) routes
If you decide to have routes reported with a metric that is calculated from
the routing table, you can manipulate the conversion formula that RIP
uses to convert a routing table metric into one that RIP understands.
4 Establish a policy to report OSPF routes so that the metrics that are
reported with these routes are imported into RIP without being changed.
Effects and Consequences
Consider the following points when you use routing policies:
■
Configure the administrative weight setting carefully because this
setting has the highest priority in resolving policy conflicts.
■
If you use routing policies, do not implement static routes. Routing
policies work with routes that are updated dynamically.
■
Use routing policies only if you need the security, or if you need more
control over the routing tables than other IP features, such as VLSMs,
give you.
■
To control whether a route is accepted or forwarded without making
specific changes to your network configuration, consider setting the
Cost metric as high as possible, and the administrative weight as low
as possible.