
IP Concepts, Terminology, and Features
308627-14.20 Rev 00
1-23
IP Routing Policies and Filters
The IP router allows you to control the flow of routing data to and from the
routing tables. This control is provided by two mechanisms:
• Accept and announce policies
• Import and export route filters
Every IP router maintains a table of current routing information. The routing table
manager receives routing updates from the network through the IP routing
protocols running on the router. Periodically, the routing table manager issues
routing updates through the protocols.
Figure 1-7
shows a router configured with all the IP routing protocols supported
by BayRS: OSPF, RIP, BGP-3, BGP-4, and EGP. The arrows indicate the direction
of flow of routing information between the network and the protocols running on
the router, between the protocols and the routing table manager, and between the
routing table manager and the routing table.
Note:
Accept and announce policies provide a superset of the parameters
provided by import and export route filters. Nortel Networks supports both IP
policies and IP route filters. However, if you are using import and export filters
for routing table management, you should migrate as soon as possible to IP
policies.
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