Key Points of Interior Routing Protocols:

•Each interior routing protocol can be

 

characterized based on the underlying 

 

the logic used by the routing protocol.

 

•The underlying logic is referred to as 

 

the TYPE of routing protocol.

•The three types are:

 

1)Distance vector

 

2)Link-state

 

3)Hybrid

The Three Classes of 

 Routing Protocols
 

 

•Distance Vector – finds the best path to 

 

a remote network using hop count. (RIP,

 

IGRP)

 

•Link State – (also called shortest-path-first 

 

protocols) – the routers each create three 

 

separate tables. 1) keeps track of directly 

 

attached neighbors, 2) topology of network, 3) 

 

the routing table. (OSPF, IS-IS)

 

•Hybrid – uses aspects of both distance vector

 

 and link state. (EIGRP)

  

Distance Vector Routing 

 

Protocols

 

 

Distance Vector Routing

 

 

Selecting the 
 
 Best Route with Metrics

 

Best Route with Metrics

 

 

 

 

Routing Loops

 

Routing Loops 

 

•Packets for network 10.4.0.0 bounce 

(loop) 

 between routers B and C.

 

 

 

TTL

 

 

•Note: IP has a Time-to-Live (TTL) field and 

 

its value is decremented by 1 at each router. 

 

–If the TTL is zero, the router drops the packet.

 

 

 

 

 

Routing Protocol

 

 

 

 

RIP

 

•Most popular.

 

•Interior Gateway Protocol.

 

•Distance Vector Protocol.

 

•Only metric is number of 

 

hops.

 

•Maximum number of hops is

 

 15.

 

•Updates every 30 seconds.

 

•Doesn’t always select fastest 

 

path.

 

•Generates lots of networks 

 

traffic.

 

 

 

IGRP and EIGRP  

 

•Cisco proprietary.

 

•Interior Gateway Protocol.

 

•Distance Vector Protocol.

 

•Metric is compose of 

 

bandwidth, load, delay and

 

 reliability.

 

•Maximum number of hops 

 

is 255.

 

•Updates every 90 seconds.

 

 

•EIGRP is an advanced 

 

a version of IGRP, that is

 

 hybrid routing protocol.

 

 

 

 

OSPF  

 

 

•Open Shortest Path First.

 

•Interior Gateway 

 

Protocol.

 

•Link State Protocol.

 

•Metric is composed of 

 

cost, speed, traffic,

 

 reliability, and security.

 

•Event-triggered updates.