Question

User information flows are transferred over an end-to-end connection in a packet switched network. The connection is routed from the source access node via one intermediate node to the destination access node across two back-to-back physical circuits inside the network, in addition to being transmitted across the interfaces between the user and the access node on the source and destination side. Assume that all physical circuits operate at the same transmission speed and have the same bit error rate p. Also assume that the circuits connecting the access nodes to the intermediate nodes have a propagation delay of t seconds and the two local access circuits have a propagation delay of a/4 seconds. Assume no queuing anywhere.

a) In terms of t, a, p and frame size determine the throughput using frame relay transmission.

b) In terms of t, a, p and frame size determine the end-to-end delay, where delay is measured as the time between the first transmission of a frame and the correct reception of the frame at the destination.

c) What is the optimum frame size for frame relay transmission in terms of throughput and delay?

Answer 1

a.

Frame relay is used to connect LANs on the public wide area networks and on private network environments. In terms of t, a, p and frame size, the throughput using frame relay transmission is as follows: (t * frame-size)/ a*p

The throughput is often measured in bits per second.

b)

In terms of t, a, p and frame size, the end-to-end delay where delay is measured as the time between the first transmission of a frame and the correct reception of the frame at the destination is as follows: (p*frame-size)/t

c)

The optimum frame size for frame relay transmission in terms of throughput and delay is 1600 bytes which is maximum frame size. This value is chosen because it is the Ethernet Maximum Transmission Unit(MTU) with the Frame Relay header added.