Question

An IP datagram has arrived with the following information in the header (hexadecimal): 46 00 00 70 00 05 01 00 18 06 00 00 7C 4E 03 02 B4 0E 0F 02 a. Are there any options? If so how many? b. Is the packet fragmented? c. What is the size of the data? d. Is a checksum used? e. How many routers can the packet travel to? f. What is the identification number of the packet?

Answer 1

Please find the following answer for the question.

Answer:

a. Are there any options? If so how many?

The given IP datagram is of 20 bytes (46 00 00 70 00 05 01 00 18 06 00 00 7C 4E 03 02 B4 0E 0F 02) and it does not option field values.

Hence it doesn't have any options and its value for options is zero.

b. Is the packet fragmented?

From the given ip header these four bytes (00 05 01 00) bit 16-18 (3 bits) will represent whether its a fragmented data or not. Here the bit 16 shows that its a fragmented packet.

c. What is the size of the data?

From the given ip header these four bytes (46 00 00 70) bit 16-31 (16 bits) will represent whether size of header and pay load.

Here is total size is 280, if we subtract 20 which is header length. We get the data length as 260.

260 is the size of data

d. Is a checksum used?

From the given ip header these four bytes (18 06 00 00) bit 16-31 (16 bits) will represent checksum and here its present and being used.

Checksum here is (0x18 06)

e. How many routers can the packet travel to?

From the given ip header these four bytes (18 06 00 00) bit 0-7(16 bits) will represent how can many routers can this travel. Here its zero and it cant travel anymore.

f. What is the identification number of the packet?

From the given ip header these four bytes (00 05 01 00) bit 0-15(16 bits) will represent the identification number. and here its 256 (0x0100) is the identification number.