Practical TCP/IP and Ethernet Networking- P12

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Practical TCP/IP and Ethernet Networking- P12: The transmitter encodes the information into a suitable form to be transmitted over the communications channel. The communications channel moves this signal as electromagnetic energy from the source to one or more destination receivers. The channel may convert this energy from one form to another, such as electrical to optical signals, whilst maintaining the integrity of the information so the recipient can understand the message sent by the transmitter....

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As a physical topology, a ring describes a network in which each node is ring until it returns to the node that originally sent it. In a ring topology, each node can act As you will see later in this chapter, since ring topologies use token passing to control access to the network, the token is returned to sender with the acknowledgment. sender then releases the token to the next node on the network. If this node has nothing to say, the node passes the token on to the next node, and so on. Physical ring networks are rare, Ring topology • A physical ring topology has minimal cable requirements • Each node can regenerate the signal • If any node goes down, the entire ring goes down • Adding or removing nodes disrupts the network ��"���!���� � A star-wired ring topology, also known as a hub topology, is a hybrid physical topology that combines features of the star and ring topologies. ring network terminology, may be connected to other hubs. disconnect a faulty node from the internal ring. By closing the circuit, the ring remains intact, but with one less node. The IBM token ring networks are the best-known example of a star-wired ring topology. In token ring The advantages of a star-wired ring topology include: The disadvantages of a star-wired ring topology include: �� ���� (� every node. access method, the first node to seek access when the network is idle will be able to The carrier sense component involves a node wishing to transmit a message listening to �� ���� ������!� When an available token reaches a node, that node can access the network for a maximum predetermined time, before passing the token on. This deterministic access method guarantees that every node will get access to the in contrast to a probabilistic access method (such as CSMA/CD), in which nodes check for network activity when they want to access the network, and the first node to claim the such networks, nodes using probabilistic access methods spend much of their time Network architectures that support the token passing access method include To transmit, the node first marks the token as ‘in use’, and then transmits a data packet, In a ring topology network, the packet is passed from node to sending the message back to the sender, who then sends the token on to the next node in In a bus topology network, the next recipient of a token is not necessarily the node that is nearest to the current token passing node. example, in an ARCnet or token bus network, the token is passed from a node to the node Networks that use token passing generally have A token ring network requires an active monitor (AM) and one or more standby lost, or sent to a node that has been disconnected from the network.