COMP 361 Tutorial Week 10

Problems of Chapter 4

 

Problem 1:

What is the 32 bit equivalent of the IP address 223.1.3.28?

 

Problem 2:

Consider a Lan to which ten host interfaces and three router interfaces are attached. Suppose the LAN uses class C addresses. The IP addresses for the 13 interfaces will be identical in which of the first 32 bits?

 

Problem 3:

Consider a router with three interfaces. Suppose all three interfaces use class C addresses. Will the IP addresses of the three interfaces necessarily have the same first eight bits?

 

Problem 4:

Consider sending a 3000 byte datagram into a link that has a MTU of 500 bytes. Suppose the original datagram is stamped with the identification number 422. How many fragments are generated and what are their characteristics?

 

Problem 5:

Describe three different types of switching fabrics commonly used in packet switches (routers)?

 

Problem 6:

 

Subnet number

Subnet Mask

Next Hop

1

128.96.39.0

255.255.255.128

Interface 0

2

128.96.39.128

255.255.255.128

Interface 1

3

128.96.40.0

255.255.255.128

R2

4

192.4.153.0

255.255.255.192

R3

5

default

 

R4

 

If this was a routing table, of a given router, the router can deliver packets directly over interfaces 0 and 1, or it can forward packets to routers R2, R3, or R4. Describe what the router does with a packet addressed to each of the following destinations

 

  1. 128.96.39.10

  2. 128.96.40.12

  3. 128.96.40.151

  4. 192.4.153.17

  5. 192.4.153.90

 

The router computes the operation IP AND mask sequentially:
(i)  if the result EQUALs the subnet number  then FORWARD to the entry in the next hop;
(ii) if not move to the next entry in the table and repeat;
(iii) if none of the entries match, then the router will FORWARD to the next hop corresponding to the DEFAULT entry.