中科大,计算机网络课件08.ppt

Chapter 8;Figure 8.1 Position of IP in TCP/IP protocol suite;;Figure 8.2 IP datagram;Figure 8.3 Service type or differentiated services;The precedence subfield was designed, but never used in version 4.;Table 8.1 Types of service;Table 8.2 Default types of service;Differentiated Services区分服务;The total length field defines the total length of the datagram including the header.;Figure 8.4 Encapsulation of a small datagram in an Ethernet frame;Figure 8.5 Multiplexing;An IP packet has arrived with the first 8 bits as shown:;In an IP packet, the value of HLEN is 1000 in binary. How many bytes of options are being carried by this packet?;In an IP packet, the value of HLEN is 516 and the value of the total length field is 002816 . Howmany bytes of data are being carried by this packet?;An IP packet has arrived with the first few hexadecimal digits as shown below:;;Figure 8.6 MTU;Table 8.5 MTUs for some networks;Fields Related to Fragmentation与分片/段相关字段;Flag field标志域;Figure 8.8 Fragmentation example;Figure 8.9 Detailed fragmentation example;分段策略;A packet has arrived with an M bit value of 0. Is this the first fragment, the last fragment, or a middle fragment? Do we know if the packet was fragmented?;A packet has arrived with an M bit value of 1. Is this the first fragment, the last fragment, or a middle fragment? Do we know if the packet was fragmented?;A packet has arrived with an M bit value of 1 and a fragmentation offset value of zero. Is this the first fragment, the last fragment, or a middle fragment?.;A packet has arrived in which the offset value is 100. What is the number of the first byte? Do we know the number of the last byte?;A packet has arrived in which the offset value is 100, the value of HLEN is 5 and the value of the total length field is 100. What is the number of the first byte and the last byte?;;Figure 8.10 Option format;Figure 8.11 Categories of options;Figure 8.12 No operation option;Figure 8.13 End of opti