its per second, in order to accommodate the high-speed, bursty transmissions of a large number of participating nodes. Up to 1024 nodes can connect to Ethernet, and each node can accommodate a number of devices. A unique characteristic of Ethernet is that messages are broadcast over the physical medium. That is, once the signal is placed on the cable, it travels in both directions, away from the sending node and out over the entire network. All nodes hear the message as it passes by, and each of them checks to see if it is addressed to itself. How- ever, observation of network traffic by the nodes is passive. They do not have to handle passing messages addressed to other nodes. Compatibility at the level of the transceiver cable interface in a network, allows nodes to be connected at wall outlets. The trans- ceiver cable can be dropped from the coaxial cable (Fig. 6-6), that is, run through the walls or over the ceiling, and can terminate in a wall outlet for network interfaces. Connection to the coaxial cable NETWORK STRUCTURES 89 Nodes Transceiver cable Coaxial cable Fig. 6-6. A typical ethernet configuration. is achieved by a simple tap. In both cases, network operation is not interrupted. The problem of managing thousands of wires is greatly reduced and there is no central switching or complex routing pro- cedures required for communication. 6.2.2 LAN Cable Medium Choices The process of putting a local area network together ultimately in- cludes the selection of a suitable cabling medium. After such issues as architecture and topology have been addressed, it is necessary to evaluate cable technologies in light of these issues and their require- ments. In addition, user concerns such as cable size, installation ease, costs, and reliability must be included in the planning process. For the media requirements of a local area network, both optical fiber and copper cabling should be considered. Each has strengths and weaknesses. For example, while optical fibers offer complete immunity to electromagnetic interfere