Networking is important for communication and data transfer and when we talk about data transfer routing is one basic concept which needs to be understood. First let us understand about data communication and then move on to routing in this episode, next episode will deal with protocols in detail.
Data communication is exchange of data or information between two nodes via a transmission medium. The flow of data from one node to another is called Data flow and there are 3 different flows
Simplex
Half duplex
Full duplex
Simplex is unidirectional e.g communication between keyboard and printer or monitor.
Half Duplex is Bi- directional but not at the same time, first information is sent it can only be received and vice versa. e.g Walkie-talkie
Full duplex is also bi-directional, and the information can be sent and received at the same time. E.g Telephone, mobile phone etc.
While sending the information we surely need to govern what, how and when is it communicated, these determining factors, or the governing rules are the Protocols. Any communication needs
A sender and receiver, a common communication language, speed of delivery and acknowledgement.
Routing tells us how and where is information sent and received. Routing uses interconnected networks to send and receive information from a source address to a destination address.
There are 3 types of routing
- Default routing
- Static routing
- Dynamic routing
Default routing where in the routers are configured to send all packets towards a single router. This approach would work well for small network settings where in there is only a single entry and exit.
Static routing is when an administrator adds routes to a routing table manually. Like default routing this also works for smaller networks and it cannot be scaled for larger networks. The advantage is there is no overhead from CPU usage point of view and the network is more secure as it is controlled by the administrator. The dis-advantages are that the administrator needs to have comprehensive knowledge to manage the routing, and each Change needs to be manually managed, hence unmanageable for large networks.
Dynamic routing is where the routing information is automatically routed by protocol and algorithms.
Advantages are that it is easy to configure and its efficiency in identifying optimal routes. Disadvantage being less secure than static and utilization of more bandwidth.
Routing Protocol finds the optimum path to transfer data or delivery packets from one network to the other. The Dynamic routing protocol uses metrics, cost, and hop counts to determine the optimal route to the destination network.
AD or Administrative Distance is the metric used for measuring the trustworthiness of the information received by the router. Its an integer between 0 to 255 where 0 is most trusted and 255 will not let any traffic pass by.
Metrics helps to determine which route to be included in the routing table when two routes are available for the same destination. The router with the smallest route will be included as this route is treated as the shortest.
Metric calculation is specific to Protocols.
- Bandwidth is used by OSPF (Open Shortest Path First)
- Hops are used by RIP(Routing Information Protocol)
- A combination of bandwidth, delay, load and reliability is used by EIGRP( Enhanced Interior Gateway Routing Protocol)
The three main classes of routing protocols are
Distance Vector Routing Protocol chooses the best path to a destination network in terms of hop counts in a particular direction. The hop count which is appearing between the source and destination networks are included. The best path identified will be the path with smallest hop count.
Link State Routing Protocol also known as SPF (shortest path first) protocols, employs more knowledge of the inter-network than the distance vector routing protocols. They consider the actual condition of the network link while calculating routes. Hence slightly more advanced algorithms are used to calculate the optimal route.
Advanced Distance Vector Routing Protocol is also known as hybrid routing protocol, as this method uses the principles of both distance vector and link state routing. Although it acts as a distance vector routing protocol as well, as it learns routes from directly connected neighbors.
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