b. Are there any options in the packet? c. What is the size of the data? d. Is the packet fragmented? e. How many more routers can the packet travel to? f. What is the protocol number of the payload being carried by the packet? We analyze each byte or group of bytes to answer the questions: a.The second hex digit in the first byte is 5 (HLEN), which means that the header length is only 5 ×4 =20 bytes. b.There are no options because the header size is only 20 bytes. c. The total length of the packet is (0054) 16 or 84 bytes. Since the header is 20 bytes, it means the packet is carrying 64 bytes of data. d.Since the flags field fragmentation offset bit is all 0s, the packet is not fragmented. e. The value of the TTL field is (20) 16 or 32 in decimal, which means the packet may visit up to 32 more routers. f. The value of the protocol field is 6, which means that the packet is carrying a segment from the TCP protocol. Prob 19- 13 In an IPv4 datagram, the value of total-length field is (00A0) 16 and the value of the header-length (HLEN) is (5)16. How many bytes of payload are being carried by the datagram? What is the efficiency (ratio of the payload length to the total length) of this datagram? payload is then 160 −20 =140. The eﬃciency = 140 / 160 =87.5%.
- Fall '15
- Networking, IP address, PROB, forwarding table, Computer Communications and Networks