CSD008/COMP3616, Networks & Internet Systems: Problem Set 4
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Reminders: There are no marks associated with these problems,
 and you do not hand in your answers. "Tanenbaum" refers to
 the 4th Edition.


1. Draw a diagram to show at which layers of the OSI model
 the following internetworking devices operate: repeater;
 bridge; router; gateway.

2. (Tanenbaum, Ch. 5, problem 3) Datagram subnets route each
 packet as a separate unit, independent of all others. Virtual
 circuit subnets do not have to do this, since each data
 packet follows a predetermined route. Does this mean that
 virtual circuit subnets do not need the capability to route
 isolated packets from an arbitrary source to an arbitrary
 destination?

3. (Tanenbaum, Ch. 5, problem 6) Assuming that all routers
 and hosts are working properly and that all software in
 both is free of all errors, is there any chance (however
 small) that a packet will be delivered to the wrong
 destination?

4. Briefly describe the principle of least-cost routing 
in packet-switching networks, mentioning some possible 
link costs.

5. The two most common routing algorithms in practice 
are distance-vector and link-state. Briefly describe 
their operation, mentioning the information exchanged 
between routers in each algorithm.

6. A routing algorithm provides the logic used by a router 
in a packet-switched network to decide, for each incoming 
packet, which output link the packet should be transmitted 
on. Briefly describe the desirable properties of a routing 
algorithm.