计算机专业英语Chapter7课件.ppt

1、内容内容l正文lNetwork TopologylSLIDING WINDOW PROTOCOLSl阅读材料lIPv6lRouter7-1 Network Topology lNetwork topologies are categorized into the following basic types:lBus topologylStar topologyl Ring topologyl Tree topologyl Mesh topologyKey Wordsltopology n.拓扑结构llayout n.布局lhybrids n.合成物lethernet n.以太网络lrepeat

2、er n.中继器ltoken ring令牌环lbackbone network 骨干网络lprotocol n.协议Key Wordslcoaxial adj.同轴的lfault tolerance 误差，错误范围（容许值）lconcentrator n.集线器lunshielded twisted pair 屏蔽双绞线NoteslA bus topology becomes slow by heavy network traffic with a lot of computer because networks do not coordinate with each other to res

3、erve times to transmit.l当一个总线拓扑结构里有很多的计算机的时候，由于网络无法协调每个计算机以保留传输时间，严重的网络拥塞会导致总线速度变慢。lOne aspect of the Ethernet protocol requires that a signal sent out on the network cable reach every part of the network within a specified length of time.Each concentrator or repeater that a signal goes through adds

4、 a small amount of time.l以太网协议的一个方面要求一个发送到网络上的信号须在预定的时间内到达网络的每一个角落。信号经过的每个网络集线器或中继器都会增加一个小的延时。7-2 SLIDING WINDOW PROTOCOLSKey Wordsldata frame 数据帧lfull-duplex 全双工lacknowledgement确认lack field应答域lpiggybacking 捎带传输ldata link layer数据链路层Key Wordsloutboundn.输出lsequence number 序号lshut off关闭NoteslWhen a dat

5、a frame arrives,instead of immediately sending a separate control frame,the receiver restrains itself and waits until the network layer passes it the next packet.l当数据帧到达时，接收者并不立即发送一个独立的控制帧，而是保留直到网络层传来下一个包。NoteslAlthough these protocols give the data link layer more freedom about the ord-er in which

6、it may send and receive frames,we have definitely not dropped the requirement that the protocol must deliver packets to the destination network layer in the same order they were passed to the data link layer on the sending machine.l尽管这些协议使得数据链路层在发送和接收帧的顺序上有了更多的自由，但是我们绝对没有放弃对此的要求，即协议发送包到目的地网络层的顺序必须和它

7、们在发送方传到数据链路层的顺序一致。Reading Material 1 IPV6 lIntroductionlIPv6 Network ArchitecturelIPv6 Communication FundamentalslInternetwork CommunicationsReading Material 2 Router Exercises 1.Network topologies are categorized into the following basic types:_,_,_,_,and _.2.A _ topology connects computers along a

8、 single or more cable to connect linearly.3.Ethernet 10BaseT is a network based on the _ topology.4.The ring topology is commonly used in _ networks that the ring of such network is concentrated inside a device called a Multistation Access Unit(MAU)and fiber Distributed Data Interface(FDDI)networks.

9、5.The _ topology provides fault tolerance.6.The way of achieving _ transmission is to have two separate com-munication channels and use each one for simplex data traffic(in different direc-tions).7.The technique of temporarily delaying outgoing acknowledgements so that they can be hooked onto the next outgoing data frame is known as _.8.In all sliding window protocols,each outbound frame contains a _,ranging from 0 up to some maximum.9.For sliding window protocols,the sender must keep _ in its memory for possi-ble retransmission.