
Customizing OSPF Services
303528-A Rev 00
7-59
Configuring OSPF Accept and Announce Policies
OSPF requires that all routers in a given area maintain a similar routing database.
To ensure the integrity of the database, OSPF does not manipulate received
link-state advertisements before propagating them on an interface.
There are two situations, however, in which an IP policy can be applied to an
OSPF interface:
• An OSPF accept policy can be used on a router to control which OSPF
non-self-originated external routing information is stored in the routing table.
This accept policy controls only what the local router uses; it does not affect
the propagation of non-self-originated external information to other routers.
• An OSPF announce policy can be used on a boundary router to control which
self-originated external routing updates are placed in the link-state database
for distribution according to the OSPF standard. The announce policy affects
what other routers learn only with regard to the local boundary router’s
self-originated information.
In configuring a policy, IP operates according to the following rules:
• IP compares routing information against the match criteria in active policies.
• Once a match occurs, IP reviews other matching policies for precedence.
• IP applies the matching policy with the highest precedence to the routing
information and takes the specified action.
• IP uses the values of any set criteria in the policy to change the content of the
routing information.
The following topics show you how to configure OSPF policies:
Topic Page
Defining an OSPF Accept Policy
7-60
Supplying Modification Values for an OSPF Accept Policy 7-63
Specifying Matching Criteria for an OSPF Accept Policy 7-65
Defining an OSPF Announce Policy 7-67
Supplying Modification Values for an OSPF Announce Policy 7-70
Supplying Matching Criteria for an OSPF Announce Policy 7-72
Comentarios a estos manuales