Avaya Configuring IP, ARP, RIP, and OSPF Services Manual de usuario descargar pdf (Pagina 33)

IP Concepts, Terminology, and Features

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In Figure 1-4, the router wants to send a packet to host C but knows only host C’s

IP address. The router uses ARP to determine host C’s physical address, as

follows:

1. The router broadcasts a special packet, called an ARP request, that asks IP

address 140.250.200.4 to respond with its physical address.

2. All network hosts receive the broadcast request.

3. Only host C responds with its hardware address.

The router maps host C’s IP address (140.250.200.4) to its physical address

(00 00 A2 00 10 40) and saves the results in an address-resolution cache for future

use.

The router can send ARP requests even if ARP, which is a dynamically loaded

module, is not currently loaded on the router. To ensure that ARP is loaded

correctly on a slot using Site Manager, choose Events Manager > Options >

Filters; then select LOADER and Debug, and choose File > Get Current Log File.

Verify that ARP is loaded on a slot by locating the following message in the log:

#xx:01/01/99 10:10:55.00 DEBUG SLOT x LOADERCODE:33

Loader service completed for ARP.EXE 0xxxxxxxxx

Routing Information Protocol (RIP)

The Routing Information Protocol (RIP) is a distance-vector protocol that enables

routers in the same autonomous system to exchange routing information by means

of periodic RIP updates. Routers transmit their own RIP updates to neighboring

networks and listen for RIP updates from the routers on those neighboring

networks. Routers use the information in the RIP updates to keep their internal

routing tables current. For RIP, the “best” path to a destination is the shortest path

(the path with the fewest hops). RIP computes distance as a metric, usually the

number of hops (or routers) from the source network to the target network.

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Avaya Configuring IP, ARP, RIP, and OSPF Services Manual de usuario Pagina 33