# Spring 2015 CSCI 373 Homework 7

This assignment is due in class on 23 April or may be uploaded to Homework 7 on moodle by 11:55 PM on 26 April. If you submit your homework with moodle, you should consider submitting in PDF.

## Problems from the textbook

Do the following problems from Chapters 3 and 2 of the textbook. A complete copy of the problems is available from the course moodle page.

• Problem 3-13 (p. 288)
• Problem 3-17 (p. 289)
• Problem 2-1 (p. 153)
• Problem 2-2 (p. 153)
• Problem 2-5 (p. 153)
• Problem 2-6 (p. 154)

## Continuing problem of packet format

This is an extension of the last problem of Homework 6.

### Continuing problem part 1

Suppose the network 152.18.69.0/24 has been divided into 16 subnets each using a mask of 28 bits. (Yes, I know this is rather silly.)

How would you express the subnets containing the hosts 152.18.69.99 and 152.18.69.116?

Suppose that every subnet contains a router which contains the binary digits 1110 as the last four bits of its 32-bit IP number. What would be the IP addresses for the routers of the subnets where 152.18.69.99 and 152.18.69.116 are located?

It is OK to use a calculator in this problem. We won’t have problems like this on the exams.

### Continuing problem part 2

The MAC address of 152.18.69.99 is 34:17:EB:98:F6:AD, and the MAC address of 152.18.69.116 is 34:17:EB:97:C2:50. The MAC address of 152.19.69.99’s only router is 00:08:E3:FF:FC:28, and the MAC address of 152.19.69.116’s only router is 00:08:E3:FF:FC:40.

Suppose an application calls the `sendto` function of the socket API to send a 2000-byte datagram to port 4444 of host 152.18.69.99. Suppose the application is sending this datagram from port 8888 of host 152.18.69.116 and that the MTU of the network connecting 152.18.69.99 and 152.18.69.116 is 1500 bytes.

In the last problem of Homework 6, you described the contents of any IP packets generated to execute the `sendto` operation. Extend your answer to include the Ethernet frame prepended to this packet. Use the format of the “Layer 1 Ethernet packet” given on the Wikipedia page but do not include the four octet 802.1Q tag.