Avaya Configuring IP, ARP, RIP, and OSPF Services Manual do Utilizador descarregar pdf (Página 46)

Configuring IP, ARP, RIP, and OSPF Services

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117356-E Rev 00

Periodically, the routing table manager announces routes to other routers in the

network as follows:

1. The routing table manager forwards a route for advertisement to the protocol.

2. The protocol consults an announce policy to determine whether or not to

advertise the route to the network.

For instructions on configuring RIP policies, see “Configuring RIP Accept and

Announce Policies” on page 5-24.

For descriptions of IP import and export filter parameters, see Appendix C

How OSPF Implements Routing Policies

The way OSPF applies accept and announce policies to routing information

differs in several ways from the procedure shown in Figure 1-7. OSPF link state

advertisements (LSAs) are received and placed in the link state database (LSDB)

of the router. The information in the LSDB is also propagated to other routers in

the OSPF routing domain.

According to the OSPF standard, all routers in a given area must maintain a

similar database. To maintain database integrity across the network, a router must

not manipulate received LSAs before propagating them to other routers. To

accomplish this, OSPF accept and announce policies act in the following manner:

• OSPF accept policies control which OSPF non-self-originated external

routing information is passed to the routing table manager. The accept policies

control only what the local router uses; they do not affect the propagation of

OSPF internal and OSPF non-self-originated external information to other

routers.

• OSPF announce policies control which self-originated external routing

updates are placed into the LSDB for distribution according to the OSPF

standard. OSPF announce policies affect what other routers learn but only

with regard to the local router’s self-originated information.

For instructions on configuring OSPF policies, see “Configuring OSPF Accept

and Announce Policies” on page 6-56.

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Avaya Configuring IP, ARP, RIP, and OSPF Services Manual do Utilizador Página 46