Avaya Configuring IP, ARP, RARP, RIP, and OSPF Services Instrukcja Użytkownika Pobierz pdf (Strona 47)

IP Concepts, Terminology, and Features

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The flow of routing information between the network, the protocols, and the

routing table manager is controlled by routing information policies.

Accept policies (and the subset of parameters provided by import filters) govern

the addition of new routes (derived from RIP, OSPF, BGP, or EGP) to the routing

tables. When RIP, OSPF, BGP, or EGP receives a new routing update, it consults

its accept policies to validate the information before entering the update into the

routing tables. Accept policies contain search information (to match fields in

incoming routing updates) and action information (to specify the action to take

with matching routes).

Announce policies (and the subset of parameters provided by export filters) govern

the propagation of RIP, OSPF, BGP, or EGP routing information. When preparing

a routing advertisement, RIP, OSPF, BGP, or EGP consults its announce policies

to determine whether the routes to specific networks are to be advertised and how

they are to be propagated. Announce policies contain network numbers (to

associate a policy with a specific network) and action information (to specify a

route propagation procedure).

For information about BGP and EGP, see Configuring IP Exterior Gateway

Protocols (BGP and EGP).

Each time that a routing update arrives from a remote router, the following steps

occur (Figure 1-8

The protocol receiving the route consults an accept policy to determine

whether to forward the route to the IP routing table manager or drop the route.

If the protocol forwards the route, the routing table manager determines

whether to inject the route into the routing table.

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Avaya Configuring IP, ARP, RARP, RIP, and OSPF Services Instrukcja Użytkownika Strona 47