| 摘要 |
The data transmission network has a controller (4) inserted in the network (1,2). The controller isolates part of the network from the greater part of the network, forming a protected zone. There will be terminals (21,22,23) on either side of the controller. When a terminal is transmitting confidential data it places a code in the header to indicate that the message is not to pass beyond the controller. The code is usually scrambled. The controller has an internal isolating switch that can interrupt the data transmission path. The switch is controlled by a validation circuit that tests the code in the header to determine whether the data is to pass. The controller will unscramble the code before testing if this is necessary. |
