Towards performance improvement of cut-through switching in computer networks

Abstract

‘Virtual cut-through’ is a relatively new computer communication switching technique. In this switching technique, messages traveling through a network need not wait and be error-checked at all intermediate nodes. A node which is found to be free is effectively bypassed by a message. The message in this case is said to have performed a cut at that node. As messages are not error-checked (and not stored) at all nodes, retransmission of an erroneous message is requested from a node where the message was last error-checked (and stored). Hence, a retransmitted message will again pass through those nodes where it had performed cuts. Therefore, this technique tends to increase the network's traffic intensity and, hence, the average network delay per message. In this paper, an improved version of virtual cut-through switching is proposed and analyzed. According to this method, a message is error-checked at every node irrespective of whether or not a cut is performed. Here, retransmission of an erroneous message is always requested from a node preceding the one where error was detected. The method is shown to be helpful in reducing the network delay per message. Several numerical results are presented in order to compare the original and improved versions of virtual cut-through switching.