Router

CISCO ROUTER:

Ø  It is internetworking device

Ø  It is a device use to connect two or more LANs.

Ø  Generally used to provide WAN connection over the internet.

Ø  It is a Network Layer or Layer-3 device that route the packet based on IP Address.

Ø  It contains OS as IOS-Cisco, JunOS-Juniper. With the help of this software, it sends packet from one network to another network.

Ø  Several manufacturing companies available in the market who manufactures routers as Cisco, Juniper, Nortel, HP, 3COM etc.

Ø  Router perform load balancing also.

Ø  Router performs following major functions 

A.     Internetworking:

Ø  It is the process or technique of connecting different networks by using intermediary device such as routers or gateway devices.

Ø  Internetworking is a term used by Cisco.

Ø  Any interconnection among or between public, private, commercial, industrial or governmental computer networks may also be defined as a internetwork or internetworking.

Ø  The most notable example of inter-networking is the “Internet”.

Ø  Internetworking is only possible when all connected networks use same protocol stack

B.     Routing:

Ø  It is the process of forwarding/moving a packet from one network to another Network (Between dissimilar networks)

Ø  Every router is maintaining routing table, that is used for making decisions about the route i.e. Best path selection is based on the type of routing we are using (Static /Dynamic)

Ø  When a host has a packet to send or when a router has received a packet to be forwarded, it reads the network address information present in the packet header to determine the ultimate destination. It looks at routing table and uses appropriate routing mechanism (static or dynamic) to find the route to the final destination.

C.     Packet Filtering

Ø  Packet filtering is a firewall technique used to control network access by monitoring outgoing and incoming packets and allowing them to pass or halt based on the source and destination Internet Protocol (IP) addresses, protocols and ports.

Ø  The router protects the network from unauthorised users i.e. unauthorised packets will be dropped here.

D.     Filling and Updating Routing Table:

Ø  Each router continuously checks network status (Learns about other networks via advertisement) communicating with neighbours (Advertisement of routing information).

Ø  Routing decisions or selecting best path is done by routers with the help of routing

protocols.

Switch vs Router