TAILIEUCHUNG - Bài giảng Chapter 4: Network layer
Chapter 4: Network layer. Introduction, network layer overview, IPv4 address, IPv4 Protocol, network routing, , network layer in an internetwork, network layer at the source, router, and destination, network layer at the source, router, and destination (continued). | Chapter 4: Network Layer Outline Introduction Network layer overview IPv4 address IPv4 Protocol Network routing Figure 1 Links between two hosts Figure 2 Network layer in an internetwork Figure 3 Network layer at the source, router, and destination Figure 4 Network layer at the source, router, and destination (continued) Communication at the network layer in the Internet is connectionless. Note IPv4 ADDRESSES An IPv4 address is a 32-bit address that uniquely and universally defines the connection of a device (for example, a computer or a router) to the Internet. Address Space Notations Classful Addressing Classless Addressing Network Address Translation (NAT) Topics discussed in this section: An IPv4 address is 32 bits long. Note The IPv4 addresses are unique and universal. Note The address space of IPv4 is 232 or 4,294,967,296. Note Figure 5 Dotted-decimal notation and binary notation for an IPv4 address Numbering systems are reviewed in Appendix B. Note Change the following IPv4 addresses from binary notation to dotted-decimal notation. Example 1 Solution We replace each group of 8 bits with its equivalent decimal number (see Appendix B) and add dots for separation. In classful addressing, the address space is divided into five classes: A, B, C, D, and E. Note Figure 6 Finding the classes in binary and dotted-decimal notation Find the class of each address. a. 00000001 00001011 00001011 11101111 b. 11000001 10000011 00011011 11111111 c. d. Example 2 Solution a. The first bit is 0. This is a class A address. b. The first 2 bits are 1; the third bit is 0. This is a class C address. c. The first byte is 14; the class is A. d. The first byte is 252; the class is E. Table 1 Number of blocks and block size in classful IPv4 addressing In classful addressing, a large part of the available addresses were wasted. Note Classful addressing, which is almost obsolete, is replaced with classless addressing. Note In IPv4 addressing, a block of .
đang nạp các trang xem trước
