e. When the token gets back to the waiting workstation, it can resume transmitting. A benefit of token passing is that it is a deterministic technique: You can always calculate the maximum delay that you'll encounter in moving informa- tion between any two points on that network, and this is especially important for applications with defined response times, such as process control. For example, an oil pipeline may have sensors in the pipelines to detect minute leakage. The oil company wants to know exactly how long it will take for the alarm from the sensor to reach the control station to shut off the valve, in order to avoid leaking oil into the community. In a LAN where there's a need to determine the delay, token passing works very well. The disadvantage of token passing is that it occurs in a unidirectional ring, SO it takes time to pass the tokens. A device has to wait until it receives a token before it can send it, and if the ring is broken because a device goes down, the ring is then unable to send tokens until the ring is recovered (i.e., the failed device is either taken out of commission or reiniti- ated). Today, almost all token-ring interfaces include an electrical shunt to pre- vent this from happening. CSMA/CD CSMA/CD is used with the Ethernet standard. CSMA/CD is a nondeterministic access method, meaning that any device can send whenever it determines that the network is clear. However, each device must listen to the network at all times because there is the potential for a collision. If a collision occurs, both sending devices back off the network and wait a random number of nanoseconds or milli- seconds before attempting to retransmit. As shown in Figure 6.5, CSMA/CD works as follows: 1. The terminals listen to the network. 2. Both of the terminals assume that the network is clear. They both start sending, but they continue listening because they know there's a chance that their messages will collide. 3. The messages do collide, SO both terminals produce a jam signal, which car- ries a bit patte