1-TCPIP基础详解.ppt

Emphasize: A range of addresses is needed to allocate address space. A valid range of addresses is between subnet zero and the directed broadcast. These RFCs provide more information about broadcasts: RFC 919, Broadcasting Internet Datagrams RFC 922, Broadcasting IP Datagrams in the Presence of Subnets Cisco’s support for broadcasts generally complies with these two RFCs. It does not support multisubnet broadcasts that are defined in RFC 922. Layer 1 of 9: Purpose: This example summarizes The IP addressing that was covered earlier in this chapter. Emphasize: In layer 1, convert the address to a binary host address. Layer 2 of 9: Emphasize: In layer 2, write the subnet mask in binary. Layer 3 of 9: Emphasize: In layer 3, draw a line after the recursive ones in the subnet mask. Layer 4 of 9: Emphasize: In layer 4, fill in zeros beyond the vertical line for the subnet. Layer 5 of 9: Emphasize: In layer 5, fill in ones beyond the vertical line for the broadcast address. Layer 6 of 9: Emphasize: In layer 6, fill in 0s beyond the vertical line except for the last bit. Make that bit a 1. This is the first usable host address. Layer 7 of 9: Emphasize: In layer 7, fill in 1s beyond the vertical line except for the last bit. Make that bit a 0. This is the last usable host address. Layer 8 of 9: Emphasize: In layer 8, copy the binary network and subnetwork address from the top row into the lower rows. Layer 9 of 9: Emphasize: In layer 9, convert binary back to dotted decimal. Layer 1 of 2: Purpose: Have the students calculate the subnet numbers and the broadcast address for each subnet from the given IP addresses and subnet masks. Layer 2 of 2: Purpose: This answers to the exercise are given in the figure. Note: Students can also find the answers to this exercise in the “Answers” appendix. Layer 2 of 3: Host B sends an ACK and acknowledges the SYN it received from host A. Host B also sends a SYN. Note that the acknowledgment field indicates host B