Fault Tolerant Networks: Data Transmission Techniques


by Youssef Edward - Date: 2010-03-19 - Word Count: 415 Share This!

Fault tolerant networks always use multiple paths as a scheme for redundancy. When data need to be transmitted across the network with multiple paths, the source of the data must choose one of the available paths. Two techniques are used for choosing the paths over which the data will be transmitted:

1. Circuit switching, connection oriented: in this scheme, the source of the data must first open a connection to the destination before sending the data. The connection will be opened by a request from the course to the destination. After the request, a temporal connection will be established that is associated with a certain path and which will be used for the data of the source that opened the connection.

After data transmission, the connection will be closed and the path that is reserved will be released. Note that the original purpose here is to determine one path for data transmission from many paths across the network. The term "circuit switching" means that a circuit or path needs to be opened first before data transmission. The term "connection oriented" means that the source must negotiate first with the destination a path before transmitting.

2. Packet switching, connectionless networks: in this scheme when the source needs to send data to the destination, it doesn't open first a connection with the destination. Rather it sends it directly to the network device (router or switch) after appending an address that defines the destination and where that data will go to. When the network device receives it checks this address and sends the data to the best path. Thus the path is determined by the address inside the packet. Thus, no circuit is required and no prior connection with the destination is required before sending the data.

Each one of the two above techniques for data transmission has its advantages and disadvantages. The circuit switching ensures that data will be transmitted even if the network is congested since it reserves a path for the user. But suppose that the user is idle and not transmitting. It will be inefficient.

On the other hand, packet switching doesn't reserve a connection and so some data may be lost and the source needs to re-transmits it. If the user is idle, the paths will be used for other users and it will be more efficient. Packet switching schemes select paths based on the address inside the data and this will be leading to more headers the attacks more link capacity. This is of course a disadvantage.

Related Tags: fault tolerant networks, data transmission techniques, packet switching, circuit switching

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