武大数据通信与网络课件Ch6yes.ppt

6.1 数据链路层 U-frame control command and response Figure 6.25 Example Figure 6.26 SVC Source-to-destination data transfer in a virtual-circuit subnet Figure 6.27 Datagram Routing table in a datagram subnet Figure 6.28 Term IP Datagram Figure 6.29 IP address formats Figure 6.30 Number of blocks and block size in classful IPv4 addressing In classful addressing, a large part of the available addresses were wasted. Note Finding the address class Figure 6.31 Figure 6.32 Network and Host Addresses Figure 6.33 A Network with Two Levels of Hierarchy Figure 6.34 A Network with Three Levels of Hierarchy Figure 6.35 Addresses in network with or without Subnet Figure 6.36 Masking Figure 6.37 Default masks for classful addressing Example for classless addressing Figure 6.38 6.4.2 Asynchronous Transfer Mode Optical fiber will allow high-speed interconnection. The differential size frames in frame relay protocol create the varying delay times. (figure 6.65) ATM uses the cell as the basic data unit in combination with switching and multiplexing. A cell is defined as a small fixed-size block of information. ATM uses asynchronous time-division multiplexing. (figure 6.66) ATM architecture（figure 6.67） A user-to-network interface (UNI) is the interface between a user and an ATM switch. a network-to-network interface (NNI) is the interface between two ATM switches. Connection between two end point is accomplished through transmission paths (TPs), virtual paths (VPs), and virtual circuits (VCs). (figure 6.68) A virtual connection is defined by a pair of numbers: the VPI and the VCI . ATM layers（figure 6.69） ATM data packet is a cell composed of 53 bytes , including 5 bytes of header and 48 bytes of payload Physical layer ATM layer: （figure 6.70） providing routing, traffic management, switching, and multiplexing se