What is protocol independence?

Protocol independence means that an application or service is able to utilize more than one communications protocol.

The most common protocol would be TCP/IP which actually encompasses different types of IP protocols such as IP or UDP. The TCP component is responsible for connection management and the IP component is the actual communications protocol. It is possible to use IP without the TCP component. This is also referred to as a connectionless protocol like UDP.

These different types of IP communications could be considered different protocols. This could be an example protocol independence if either can be used for a specific application.

There are less common protocols like Novell's IPX/SPX which do not interoperate with TCP/IP in any way. However, there are applications that can use either protocol making them completely protocol independent.

Both TCP/IP and IPX followed the OSI model, and it is possible to load both protocols on the same network interface on a host, and even on a Cisco router as a sub-interface. Remember that the lower levels of the OSI model such as physical, data, network and transport are open and can be replaced with different media and or data frame size etc.

Try to find a detailed OSI model and you will see more than one protocol within the transport layer. This would also help in understanding protocol independence.

It is also possible to encapsulate or hide one protocol inside of another to allow say NetBiOS or IPX to be carried over an IP network within a pure IP packet. This requires that all the IP packet header and footer be stripped away and the inside or encapsulated protocol to be handed off to a higher OSI layer such as the Session layer.

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