All About Router

8/3/2019 All About Router

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Types of Router

Routers provide connectivity inside enterprises, between enterprises and the Internet, and within an

Internet Service Provider (ISP)

One of the largest routers e.g. the Cisco CRS-1 or Juniper T1600 interconnects internet Service Providers

(ISPs), they are used within ISPs, or may be used in very large enterprise networks. The smallest routers

provide connectivity for small and home offices.

Edge Router

This type of router are placed at the edge of the ISP network, the are normally configured to external

protocol like BGP (Border gateway protocol) to another BGP of other ISP or large organisation.

Subscriber Edge Router

This type of router belongs to an end user (enterprise) organization. Its configured to broadcast

external BGP to its providers AS(s)

Inter-provider Border Router

This type of router is for Interconnecting ISPs, this is a BGP speaking router that maintains BGP sessions

with other BGP speaking routers in other providers' ASes.

Core Router

A router that resides within the middle or backbone of the LAN network rather than at its periphery. In

some instances , a core router provides a stepdown backbone , interconnecting the distribution routers

from multiple building of a campus ( LAN), or Large enterprise Location (WAN). They tend to beoptimized for a high brandwidth.

Wired and Wireless Routers.

Home and small office networking is becoming popular by day by the use of IP wired and wireless

router.Wired and wireless router are able to maintain routing and configuration information in their

routing table. They also provide the service of filtering traffic of incoming and outgoing packets based

on IP addresses.

Some wireless routers combines the functions of router with those of a network switch and that of a

firewall in one.


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A router is specialized computer connected to more than one network. A router runs software that

allows the device to move data from one network to another. Routers operate at the network layer (OSI

Model's layer 3). The primary function of a router is to connect networks together and keep certain

kinds of broadcast traffic under control. There are several companies that make routers: Cisco (Linksys),

Juniper, Nortel (Bay Networks), Redback, Lucent, 3Com, and HP just to name a few.

Why do I need a Router?

Routers used in networks perform the following functions:

Restrict network broadcasts to the LAN

Act as the default gateway.

Move data between networks

Learn and advertise loop free paths

Restrict Broadcasts to the Local LAN

Networks (especially Ethernet networks) use broadcast communication at the datalink and network

layer. Network layer broadcasts are transmissions sent to all hosts using the network layer protocol(usually Internet Protocol [IP] or IPX). Network broadcast communication is used to communicate

certain kinds of information that makes the network function (ARP, RARP, DHCP, IPX-SAP broadcasts

etc.). Since several devices could attempt to transmit simultaneously and cause collisions, it is preferable

to separate large sets of hosts into different broadcast domains using a switch, or router.

As the number of hosts on the network increases, the amount of broadcast traffic increases. If enough

broadcast traffic is present on the network, then ordinary communication across the network becomes

difficult.

To reduce broadcasts, a network administrator can break up a network with a large number of hosts

into two smaller networks. Broadcasts are then restricted to each network, and the router performs asthe 'default gateway' to reach the hosts on the other networks.

Act as the Default Gateway

Especially in today's networks, people are connecting to the Internet. When your computer wants to talk

to a computer on another network, it does so by sending your data to the default gateway (your local

router). The router receives your data, looks for the remote address of that far-off computer makes a

routing decision and forwards your data out a different interface that is closer to that remote computer.

There could be several routers between you and the remote computer, so several routers will take part

in handing off the packet, much like a fireman's bucket brigade.

A router can take in an Ethernet frame, strip the ethernet data off, and then drop the IP data into a

frame of another type. In this way a router can also perform 'protocol conversion', provided it has the

appropriate hardware and software to support such a function. The whole point, however, is to forward

the data from the interface it receives data on, to another interface that retransmits the received data

onto another interface serving another network.

Move Data between Networks


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Routers have the capability to move data from one network to another. This allows two networks

managed by different organizations to exchange data. They create a network between them and

exchange data between the routers on that network. Because a router can accept traffic from any kind

of network it is attached to, and forward it to any other network, it can also allow networks that could

not normally communicate with each other to exchange data. In technical terms, a token ring network

and an ethernet network can communicate over a serial network. Routers make all this possible.

Learn and Advertise Loop-Free Paths

Over time, routing protocols (RIP, OSPF, IS-IS, IGRP, EIGRP, BGP) have been invented so that very large

network systems with lots of sub-networks can automatically learn where the various networks are tell

other routers and move data between them automatically. This is how data makes it across the Internet.

DO I REALLY NEED A ROUTER?

If you have a small network, with few hosts, you probably don't need a router unless you are connecting

your network to another network. For example, the Internet is a very large network, so you would need

a router (and a lot of other things) to connect your network to the Internet.


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The function of a router is to manage the paths along which information is forwarded within a network.

They are necessary to facilitate communication between computers and the Internet.

Internet data is transferred through the TCP/IP networking protocols that are designed to communicate

data. When it is transmitted, the data is split into fragments called packets. A router is designed to direct

these packets to the correct destination along the best possible route, hence the name, router.

Routers range in size from the small ones we have in our homes and that are available from computer

shops and from Internet Service Providers, to absolutely huge models that manage huge flows of data

between computer networks and throughout the Internet. The smaller, home-based models make it

possible to share one Internet connection between a few computers on the network, and this enables

more than one person to use it, whereas the larger ones are far more intricate and have many multi-

function routing devices.

Routers come in two basic types: Dynamic and static. The dynamic comes already programmed to

manage data traffic across the network, which is managed by a routing protocol, whereas a static router

needs to be manually configured by a network administrator who programs all of the necessary routes

that are needed for data packets.

Essential services and utilities can be integrated into a network so that it is more secure and responds

more efficiently. For example, a router can be made to incorporate a security feature such as a firewall

for added protection against viruses and other nasties that have the ability to destroy computers and

enable hackers to gather our personal information. It is also possible to increase network function by

integrating services such as IP voice, or video capability.

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All About Router