Question

a) The performance of the Ethernet protocol goes to 1(100%) when propagation delay goes to zero. Can you briefly explain why ?

b) The performance of the Ethernet goes to 1(100%) when the maximum frame size goes to infinity . Can you briefly explain why ?

Answer 1

Propagation delay is a measure of the time required for a signal to propagate from one end of the circuit to the other. Network propagation delay is measured in nanoseconds (nS). Typical propagation delay for category 5e UTP is a bit less than 5 nS per meter (worst case allowed is 5.7 nS/m).

Relating to the propagation of the bits at the speed of light (for the transmission medium in question). This delay is the distance divided by the speed of light; for 1,000 m of Ethernet cable, with a signal propagation speed of about 230 m/µsec, the propagation delay is about 4.3 µsec. That is, if we start transmitting the 1500 byte packet of the previous paragraph at time T=0, then the first bit arrives at a destination 1,000 m away at T = 4.3 µsec, and the last bit is transmitted at 120 µsec, and the last bit arrives at T = 124.3 µsec.

So, ethernet performance is 1(100%), when propogation delay goes to zero.

When the max frame size reaches to inifnity the propogation is easy as size of frame is infinity means more than standard size i.e 1500 so, because of this performance of ethernet goes to 1(100 %).