Ccna routing and Switching Complete Study Guide

Route Update Packets    These packets are used to update neighboring routers about the 

networks connected to all routers within the internetwork. Protocols that send route 

update packets are called routing protocols; the most critical ones for CCNA are RIPv2, 

EIGRP, and OSPF. Route update packets are used to help build and maintain routing 

tables.

Figure 1.14 shows an example of a routing table. The routing table each router keeps and 

refers to includes the following information:

f I g u r e   1.14     Routing table used in a router

1.0

3.0

1.3

E0

2.1

S0

NET

2.2

S0

3.3

E0

1.1

1.2

3.1

3.2

1

2

3

INT

Routing table

E0

S0

S0

Metric

0

0

1

NET

1

2

3

INT

Routing table

S0

S0

E0

Metric

1

0

0

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The OSI Reference Model