ROUTERROUTER

DefinitionDefinition

A router is a computer networking device that A router is a computer networking device that forwards data packets toward their destinations forwards data packets toward their destinations

through a process known as routing.through a process known as routing.

ExplanationExplanation

A router is a device that forwards data A router is a device that forwards data packets between computer network creating an packets between computer network creating an overlay internetwork.overlay internetwork.

A router is connected to two or more data lines from A router is connected to two or more data lines from different networks. When a data packet comes in different networks. When a data packet comes in one of the lines, the router reads the address one of the lines, the router reads the address information in the packet to determine its ultimate information in the packet to determine its ultimate destination. destination.

Then, using information in its routing Then, using information in its routing table or routing policy, it directs the packet to the table or routing policy, it directs the packet to the next network on its journey. next network on its journey.

Routers perform the "traffic directing" functions on Routers perform the "traffic directing" functions on the internet. A data packet is typically forwarded the internet. A data packet is typically forwarded from one router to another through the networks that from one router to another through the networks that constitute the internetwork until it reaches its constitute the internetwork until it reaches its destination nodedestination node

History History (Cont…)(Cont…)

The first broadband networks emerged in the later The first broadband networks emerged in the later portion of the 1990's.The initial high speed offerings portion of the 1990's.The initial high speed offerings were centered around the cable industry and its were centered around the cable industry and its associated high speed offerings through cable associated high speed offerings through cable modems. modems.

ADSL technology predates the cable offerings of ADSL technology predates the cable offerings of high speed access in the home and business, but it high speed access in the home and business, but it came to the commercial market approximately one came to the commercial market approximately one to two years after the introduction of cable to two years after the introduction of cable technologies in 1996. technologies in 1996.

Router technology evolved parallel to the increase Router technology evolved parallel to the increase in bandwidth availability. As the technology in bandwidth availability. As the technology improved, router cost was driven down at the same improved, router cost was driven down at the same time that router manufacturers provided greater time that router manufacturers provided greater automation for router installation. automation for router installation.

These factors enabled the average consumer to be These factors enabled the average consumer to be capable of establishing wired-and later wireless-capable of establishing wired-and later wireless-networks in the home and business.networks in the home and business.

There are two major groups of router interfaces:There are two major groups of router interfaces:

LAN InterfacesLAN Interfaces

WAN InterfacesWAN Interfaces

LAN InterfacesLAN Interfaces

Are used to connect router to LAN networkAre used to connect router to LAN network

Has a layer 2 MAC address Has a layer 2 MAC address

Can be assigned a Layer 3 IP addressCan be assigned a Layer 3 IP address

Usually consist of an RJ-45 jack Usually consist of an RJ-45 jack

WAN InterfacesWAN Interfaces

Are used to connect routers to external networks Are used to connect routers to external networks that interconnect LANs.that interconnect LANs.

Depending on the WAN technology, a layer 2 Depending on the WAN technology, a layer 2 address may be used.address may be used.

Uses a layer 3 IP address Uses a layer 3 IP address

TYPES OF ROUTERS:TYPES OF ROUTERS:

There are several types of routers in the market.There are several types of routers in the market.Broadband RoutersBroadband Routers

Wireless RoutersWireless Routers

Core RoutersCore Routers

Edge RouterEdge Router

Broadband RoutersBroadband Routers

A device that provides access to the Internet for multiple A device that provides access to the Internet for multiple computers.computers. It typically includes a network switch with four It typically includes a network switch with four or more Ethernet ports for wired connections to desktop and or more Ethernet ports for wired connections to desktop and laptop computers.laptop computers.

The router also provides network address translation (NAT), The router also provides network address translation (NAT), which allows multiple users to reach the Internet with one which allows multiple users to reach the Internet with one public IP address assigned by the cable or telephone public IP address assigned by the cable or telephone company to the service outers capture the information that company to the service outers capture the information that come through broadband connection via a modem and come through broadband connection via a modem and deliver it to your computerdeliver it to your computer

The router choose route for the packet so that you receive The router choose route for the packet so that you receive the information Firstly. Routers are multiport devices and the information Firstly. Routers are multiport devices and more sophisticated as compared to repeaters and bridges.more sophisticated as compared to repeaters and bridges.

Wireless RoutersWireless Routers

Wireless routers create a wireless signal in your home or Wireless routers create a wireless signal in your home or office. So, any computer within range of Wireless routers office. So, any computer within range of Wireless routers can connect it and use Internet.can connect it and use Internet.

It works much like a wired router but replaces wires with It works much like a wired router but replaces wires with wireless radio signals to communicate within and to wireless radio signals to communicate within and to external network environments.external network environments.

It enables you to run a computer or gaming system from It enables you to run a computer or gaming system from anywhere in the house without having to run cables through anywhere in the house without having to run cables through the wallsthe walls

In order to secure your Wireless routers, you simply need to In order to secure your Wireless routers, you simply need to come secure it with password or get your IP address. Then, come secure it with password or get your IP address. Then, you'll log on into your router with the user ID and you'll log on into your router with the user ID and passwords will that come with your routerpasswords will that come with your router

Core RouterCore Router

A core router is a router designed to operate in the A core router is a router designed to operate in the Internet backbone, or core. Internet backbone, or core.

To fulfill this role, a router must be able to support To fulfill this role, a router must be able to support multiple telecommunications interfaces of the multiple telecommunications interfaces of the highest speed in use in the core Internet and must be highest speed in use in the core Internet and must be able to forward IP packets at full speed on all of able to forward IP packets at full speed on all of them. It must also support the routing protocols them. It must also support the routing protocols being used in the core.being used in the core.

Edge RouterEdge Router

Edge devices are that which provide entry points Edge devices are that which provide entry points into enterprise or service provider core networks. into enterprise or service provider core networks. Examples include routers, routing switches, Examples include routers, routing switches, integrated access devices (IAD), multiplexers, and a integrated access devices (IAD), multiplexers, and a variety of metropolitan area network (MAN) and variety of metropolitan area network (MAN) and wide area network (WAN) access devices. Edge wide area network (WAN) access devices. Edge devices also provide connections into carrier and devices also provide connections into carrier and service provider networks.service provider networks.

Routing ProtocolsRouting Protocols

A routing protocol specifies A routing protocol specifies how routers communicate with each other, how routers communicate with each other, disseminating information that enables them to disseminating information that enables them to select routes between any two nodes on a select routes between any two nodes on a computer network.computer network.

Routing algorithms determine the specific choice of Routing algorithms determine the specific choice of route. Each router has a priori knowledge only of route. Each router has a priori knowledge only of networks attached to it directly.networks attached to it directly.

A routing protocol shares this information first A routing protocol shares this information first among immediate neighbors, and then throughout among immediate neighbors, and then throughout the network. This way, routers gain knowledge of the network. This way, routers gain knowledge of the topology of the network.the topology of the network.

Types of routing protocolsTypes of routing protocols

Enhanced Interior Gateway Routing Protocol Enhanced Interior Gateway Routing Protocol (EIGRP)(EIGRP)

Interior Gateway Routing Protocol (IGRP)Interior Gateway Routing Protocol (IGRP)

AdvantagesAdvantages

Connecting an Internet modem directly to a PC Connecting an Internet modem directly to a PC exposes that PC to a host of security issues.exposes that PC to a host of security issues.

A router is not a replacement for a firewall or anti-A router is not a replacement for a firewall or anti-malware measures, but it’s an important first step malware measures, but it’s an important first step towards a largely secure network environment.towards a largely secure network environment.

Using a router as an intermediary between the Using a router as an intermediary between the “outside” network of the Internet and the “inside” “outside” network of the Internet and the “inside” network of your organization provides a scalable network of your organization provides a scalable environment that is also, to a degree, easier to environment that is also, to a degree, easier to secure.secure.

DisadvantagesDisadvantages

routers add additional IP-based headers. These routers add additional IP-based headers. These headers include information such as source and headers include information such as source and destination addresses, UDP information and destination addresses, UDP information and checksums. These headers are attached to every checksums. These headers are attached to every payload of data. payload of data.

Large pieces of data are typically broken into Large pieces of data are typically broken into thousands of smaller headers, making this header thousands of smaller headers, making this header data consume a percentage of the total available data consume a percentage of the total available bandwidth.bandwidth.

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