INLS184: Protocols and Network Management
Assignment #3: due April 12th 2005

All About Subnetting and Network Prefixes and CIDR!

Question #1:
Let's say we have a campus environment with fewer buildings than UNC-CH, but more widely populated. (Maybe about 50 buildings, with AS MANY AS 1000 COMPUTERS PER BUILDING; each building is connected to the campus network through a router/layer 3 switch.) I have a Class B network ( for the whole campus, but I want to run RIP (why, I don't know) so I need the SAME subnet mask across the whole campus.   (Remember: RIP version 1 doesn't support variable length subnet masks within a given network.)

Your task, should you chose to accept it: What would be the range of network addresses in each building (you don't have to give it to me for all 50, the first few buildings would do) as well as the common subnet mask across the whole campus? Also, are there any IP addresses in these ranges that you COULD LEGALLY assign to hosts that you might not want to? If so, why?

Question #2:
Assume that you have been assigned the network block   You need to establish eight subnets.
(a) How many binary digits are required to define eight subnets?
(b) Specify the extended-network-prefix that allows the creation of eight subnets.
(c) Express the subnets in binary format and dotted decimal notation.
(d) List the range of host addresses that can be assigned to the 4th subnet in that list of subnets.
(e) What is the broadcast address for that subnet?

Question #3:
List the individual networks defined by the CIDR block

Question #4:
How would you express the entire Class B address space as a single CIDR advertisement?
(Hint: how many bits do they all have in common?   Hint to hint: look at the diagram of the structure of the classes of IP addressing in the Comer book.   Hint to hint to hint:  see Comer chapter "IP: Internet Protocol Addresses".   No more hints!)

Question #5:
Recalling our discussion of how CIDR addressing allows for route aggregation, aggregate the following set of four IP /24 network addresses: