Swich and Router

• Switch

     Switches generally have a more intelligent role than hubs. A switch is a multi-port device that improves network efficiency. The switch maintains limited routing information about nodes in the internal network, and it allows connections to systems like hubs or routers. Strands of LAN's are usually connected using switches. Generally, switches can read the hardware addresses of incoming packets to transmit them to the appropriate destination.

• Router

     Routers help transmit packets to their destinations by charting a path through the sea of interconnected networking devices using different network topologies. Routers are intelligent devices, and they store information about the networks they’re connected. Most routers can be configured to operate as packet-filtering firewalls and use access control lists (ACLs). Routers, in conjunction with a channel service unit/data service unit (CSU/DSU), are also used to translate from LAN framing to WAN framing. This is needed because LANs and WANs use different network protocols. Such routers are known as border routes. They serve as the outside connection of a LAN to a WAN, and they operate at the border of your network.

Routing

IP routing is the process of sending packets from a host on one network to another host on a different remote network. This process is usually done by routers. Routers examine the destination IP address of a packet , determine the next-hop address, and forward the packet. Routers use routing tables to determine a next hop address to which the packet should be forwarded.

In other word, “Routing is the process of selecting a path for traffic in a network or between or across multiple networks.”

Consider the following example of IP routing:

Host A wants to communicate with host B, but host B is on another network. Host A is configured to send all packets destined for remote networks to router R1. Router R1 receives the packets, examines the destination IP address and forwards the packet to the outgoing interface associated with the destination network.

Types of Routing

There are three types of routing.

1. Static Routing
2. Dynamic Routing
3. Default Routing