
Configuring IP Services
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117356-B Rev. 00
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
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Supplying Override Values for an OSPF Accept Policy 7-62
Specifying Matching Criteria for an OSPF Accept Policy 7-64
Defining an OSPF Announce Policy 7-66
Supplying Override Values for an OSPF Announce Policy 7-69
Supplying Matching Criteria for an OSPF Announce Policy 7-71
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