Q1

This question has three parts:

In a short paragraph (200-300 words) explain the fundamentals of Packet Switching and how it works.

In a short paragraph (200-300 words) explain the fundamentals of Circuit Switching and how it works.

Using your own words, in a short paragraph (200-300 words) discuss and explain why packet switched networks are used for data communication instead of circuit switched.

Q2

An ISP is granted a block of addresses starting with 110.50.0.0/16. The ISP needs to distribute these blocks to 2600 customers in the following three groups:

The first group has 200 medium-size businesses; each needs approximately 120 addresses.

The second group has 400 small-size businesses; each needs approximately 20 addresses.

The third group has 2000 households; each needs 6 addresses.

Design the sub blocks and give the slash notation for each sub block. Find out how many addresses are still available after these allocations. You need to show your working and math and explain how your achieved your sub-netting solutions. Write your subnets in a table like the following.

Group Number of Businesses Users per business Subnet (---.---.---.--- / ---) Number of remained usable addresses in the subnet

1 200 120
2 400 20
3 2000 6

Q3

Using this diagram, answer the following routing questions:

A packet arrived at router R1-m2 with destination address 145.80.23.14. Explain how it is forwarded to its destination.
A packet arrived at router R2-m0 with destination address 170.14.24.12. Explain how it is forwarded to its destination.
A packet arrived at router R3-m0 with destination address 135.15.42.18. Explain how it is forwarded to its destination.

Q4

A router with IP address 132.145.132.112 and Ethernet physical address of a1:a2:a3:a4:a5:a6 has received a packet for a host destination with IP address 152.111.178.110. The router does not know about the Ethernet physical address of the host. Assume the Ethernet address of the destination host is b1:b2:b3:b4:b5:b6 and the router is going to find it through and ARP request.

Show the entries in the ARP request packet sent by the router. Encapsulate this packet in a data link frame and fill all the fields.
Show the entries of the ARP packet sent in response to the packet in first part. Encapsulate this packet in a data link frame and fill all the fields. < br/>Hint: Use example 8.1 as a template to explain your answer. Use the same drawing tradition to show your packets.

Q5

This question has three parts:

In a short paragraph (200-300 words), explain ICMP and why it is important.

In a short paragraph (200-300 words) explain "ping" and "traceroute" in UNIX --or "tracert" in Windows--, how they work and how they are different.