MT2: UNIT 2 ROUTING – MULTIMEDIA APPLICATION DEVELOPMENT

ROUTING OR ROUTEING

Routing or routeing is the process of selecting paths in a network along which to send network traffic. Routing is performed for many kinds of networks, including the telephone network (Circuit switching) , electronic data networks (such as the Internet), and transportation networks. In packet switching networks, routing directs packet forwarding, the transit of logically addressed packets from their source toward their ultimate destination through intermediate nodes, typically hardware devices called routers, bridges, gateways, firewalls, or switches.

Routing, in a more narrow sense, is often contrasted with bridging in its assumption that network addresses are structured and that similar addresses imply proximity within the network. Because structured addresses allow a single routing table entry to represent the route to a group of devices, structured addressing (routing, in the narrow sense) outperforms unstructured addressing (bridging) in large networks, and has become the dominant form of addressing on the Internet, though bridging is still widely used within localized environments.

Routing is a key feature of the Internet because it enables messages to pass from one computer to another and eventually reach the target machine. Each intermediary computer performs routing by passing along the message to the next computer. Part of this process involves analyzing a routing table to determine the best path.

Routers are more advanced devices used to connect separate networks to form an internetwork. An internetwork is created when two or more independent networks are connected yet continue to function separately. A network grows and become a more integral part of an organization. It is a common request to supply multiple paths through a network to provide fault tolerance. A bridge cannot handle multiple paths for data and can in fact, create a situation in which the packet can travel in an endless loop. Routers can be used like bridges to connect multiple network segments and filter traffic, also, unlike bridges, routers can be used to form complex networks.

As shown in Figure below, routers can connect complex networks with multiple paths between network segments. Each network segment, also called a sub network (or subnet), is assigned a network address. Each node on a subnet is assigned an address as well. Using a combination of the network and node address, the router can route a packet from the source to a destination address somewhere else on the network.

To successfully route a packet through the internetwork, a router must determine the packet’s path. When the router receives a packet, it analyzes the packet’s destination network address and looks up that address in its routing table. The router then repackages the data and sends it to the next router in the path.

Because routers operate at a higher layer of the OSI model than bridges do, router can easily send information over different network architectures. For example, a packet received from a token ring network can be sent over an Ethernet network. The router removes the token ring frame, examines the packet to determine the network address repackages the data into Ethernet frames and sends the data out onto the Ethernet network.

Dynamic routers are easier to maintain and provide better route selection than static routers, but the routing table updates and discovery generate additional network traffic. This is especially true with distance-vector protocols such as RIP, which sends its entire routing table across the network every 30 seconds.

SELF ASSESSMENT EXERCISE

Mention the essential features of a Router

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4.0 CONCLUSION

In this unit, we highlighted the process of Routing. We learnt the relationship level between the Router and the Internet.