(15 points) Define or explain the following terms:
count to infinity problem
virtual circuit vs. packet switched
(15 points) Consider using a 4khz channel and 16 discrete levels to send data.
(15 Points) A cellular phone system needs to accommodate many users. Explain how the system uses space, frequency, and time division multiplexing.
(20 Points) List the seven layers of the ISO/OSI reference model and for each layer provide an example of a function commonly performed at that layer.
(20 points) Consider routing in a network with 200 routers, and on average every router is connected to 4 other routers. Routing information is exchanged every 100msec. How much network bandwidth is used under link-state and distance vector routing to exchange this information. Assume sequence numbers are used to damp flood packets for link-state. Please explain any assumptions you make about the size of routing table entries.
(15 points) In a broadcast channel, link bandwidth is wasted due to multiple hosts trying to send at once and canceling each others communication. A simple model of this problem is that time is divided into discrete slots. If a network has n hosts, and the probability of any single host trying to use a slot is p, what fraction of slots are wasted due to collisions?