Part 19- Router (Networking Devices)- Computer Networking- CCNA

Hello friends...i am Vasu Birla and today will discuss about the most important Networking Device ..Router.  so let's start...

ROUTER

Router is a device which connect two or more networks together, which is why router is also known is Inter-networking device also. Inter-networking means two or more networks are connected together with the help of router. one more thing router is just like a computer  but it is designed for routing only, our computer can be router also but that are software router while hardware router which are specialize for routing is more efficient and fast than software router. 

There is a Operating System installed on router which get moves data from one network to another network with the help of routing table. 

Router does work on Network layer or Layer 3 of the OSI model. 

Cisco Router

There many companies which manufacture Router but main companies are -

Cisco , Juniper , HP, 3com and Nortel 

Functions of Router

1. To connects multiple networks together.

2. Restrict broadcasts in LAN-  Control the Broadcast traffic -

.

Broadcasts means transmissions sent to all hosts. Without broadcast it is hard to establish communication with all hosts. So many protocols communicate each other via broadcast , some important protocols are -

ARP  means Address resoultion protocol

RARP means Reverse Address resolution protocol 

DHCP means Dynamic Host Configuration Protocol 

without broadcast these protocols can not function. but one to all broadcast create problem of huge data traffic.   So we don't remove broadcast totally , we only restrict broadcast from LANs using a device known as Router. There is no problem in small networks but  as much as host are added continuously so one to all broadcast create problem of huge data traffic, because these broadcast traffic collision is done between data packets and data would be loss. 

Solution of this problem is router , Router divide the these big broadcast collision in to small different collision domain.

3. Works as the default gateway- 

Suppose there is a LAN with few hosts with same range ip addresses , so then can communicate directly but on the internet if any host wants communicate with someone which have different range of IP address configured so without router it is impossible because there is also IP address configured on Router which act as a default gateway , we can understand with its name its gateway to world of internet it provide the optimal path to communicate with that host. all host must be configured that router ip in their own TCP/IP suit. 

Maximum we see that there is no router in our office ,home  we use Modem instead i want to say that modem act as a router also that Modem uses a Technique called ADSL means Asymmetric  Digital Subscriber Line. 

With the help of this ADSL modem we can connect our PC to internet. there are many routers between our source computer and destination.

4. Move (Route) data among multiple network

Router find the best path for routing data from one network to another network. It allow two networks managed by different organization to exchange data. and Router connect any kind of networks whether there are two different protocols are used it does not matter.

6. Select Optimal path for routing data-  

Router learn about paths and advertise them to other routers for routing data fast via optimal paths. there are many routers on world wide web network in this word. 

Once router get the paths and routers , it will save the all information about network, paths and routers in its own table  and in future it select best path and router on the basis of this table  which contain different path information. 

There are three ways to find route- 

- Directly connected - first of all Router fill the information in routing table about those all routers which are directly connected.

Static routing - In which Network Administrator configure router to tell that , what is the best route to move data from one router to another. 

Dynamic Routing-  In which Network Administrator Configures different routing protocols and after that with help of that protocols router automatically find the best path for move data.