networks ch3

default gateway

is a node that enables a connection between networks in order to

allow machines on other networks to communicate.

default gateway.

When a host wants to reach a destination that is outside of its own network, it has to

use a

Router

the basic backbone for the Internet.

Router

main function of the router is to connect two or more

than two network and forwards the packet from one network to another.

Routing and Routing Protocols:

The primary responsibility of a router is to direct packets destined for

local and remote networks

Simplicity and low overhead—

Ideally efficient routing algorithm functionality is achieved if the routers have

minimum CPU and memory overhead.

Rapid convergence—

Convergence is the process of all routers agreeing on routes.

When a network event causes changes in router availability, recalculations are needed to reestablish network

connectivity.

Flexibility—

A routing algorithm should quickly adapt to a variety of network changes. These changes include

router availability, changes in bandwidth, queue size, and network delay.

Routing protocols

can be classified in many different ways, such as Interior gateway

protocol IGPs or Exterior gateway protocol EGPs.

Routing Information Protocol (RIP)—

The most common IGP in the Internet,

RIP uses hop count as its routing metric.

Interior Gateway Routing Protocol (IGRP)—

Cisco developed this IGP to

address the issues associated with routing in large, heterogeneous networks.

Link-State Protocols

Link-state routing

protocols were designed to overcome the limitations of distance vector routing protocols. Link-

state routing protocols respond quickly to network changes

Speed of convergence:

Speed of convergence defines how quickly the routers in the network topology

share routing information and reach a state of consistent knowledge.

Scalability

defines how large a network can become, based on the routing protocol that is

deployed

Classful or classless (use of VLSM):

Classful routing protocols do not include the subnet mask and

cannot support variable-length subnet mask (VLSM).

Resource usage:

includes the requirements of a routing protocol such as memory space

(RAM), CPU utilization, and link bandwidth utilization.

Implementation and maintenance:

describes the level of knowledge

that is required for a network administrator to implement and maintain the network based on the routing

protocol deployed.