Subnet Division Case Study

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24 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Subnet Division Case Study


By


Marc Grosz

Steve Griffin

Tari Mitzel

Jeff Bradford

Geoff Vining

Kristen Jordan













Dealing with a Class B network and dividing up the IP’s is a daunting task and is often
done with a subnet ma
sk of 255.255.255.0.

The reason for this

is
that

each time more IP’s are
needed
,

only 254
useable

IP’s are actually given, minimizing IP waste
, at least somewhat
. This
case study also leaves many questions to be answered so many assumptions must be taken

in
order to sufficiently answer the division questions. The assumptions are listed in Appendix A.


Now that we know computer network IP groupings will be given out in groups of 254 it
is pretty simple to figure out how many subnets need to be given to
each college, building,
department, etc. This answer will focus more on the campus
-
wide distribution of subnets in a
more general fashion due to the fact of not knowing the growth patterns, limitations of building
(capacity
-
wise as well as infrastructure
-
wise).

Due to the number requirements of each building,
we want to assume that either that building is currently, or in the near future, will need one
computer for each person. This is an acceptable assumption as well due to the fact that the
current req
uirements of the entire campus for each building totals 19,300 (not including
necessary router, gateway, etc. IP consumption), whereas the Class B network can support
65,024 IPs. We decided to thus give, in numeric order, the current requirements of each

building their due amount and leave the rest of the IP’s free for future expansion.

Appendix A
shows the number of subnets each building gets depending upon if it belongs to a large college
(4 subnets per building), a small college (5 subnets per buildin
g), the administration (1 subnet
per building), or the residence halls (2 subnets per building). Appendix B shows the specific
subnet distribution among these buildings as well. Since there is not sufficient need for the
entire Class B network there are
many subnets left completely unused.
These will

be left for
future need and expansion of the campus.


Now that the IP ranges are distributed, the computer hosts themselves must have some
way of receiving an IP number so it can connect and communicate with

the rest of the network
and outside the campus network as well. We have decided that DHCP is what will work best in
this situation. Of course there will be need for static IP’s across campus, these are typically only
given to servers, routers, gateways,

printers, etc. With the use of DHCP, there will be the need
for a DHCP server
for each subnet so to receive this IP through DHCP, however the Default
Gateway can take this responsibility to cut down on the IP waste that will occur through network
infrast
ructure setup. Although DHCP is used, it is also important to point out that we want to
utilize its dynamic IP allocation capability. One worry is that if there
is

UNIX servers on
campus
,

those servers may want
to utilize the BOOTP IP allocation protocol
. This worry

is
completely unnecessary
because of DHCP’s requirement of being backwards compatible with
BOOTP.


As a result, but splitting up the network into this size of subnets, performance can stay
optimal without tremendous waste of IP’s. Through t
he use of DHCP’s dynamic allocation, IP
administration is very easy
, especially when static IP’s are needed. The main concern of this
setup is how many routers, gateways, printers, etc. will be taking up IPs. Although there has
been sufficient slack give
n to each building, there can be an extreme waste of IPs. Worse yet,
when the IP’s are distributed among the building, the building network administrator may try to
give each department a certain range of IP’s. This results in needing more subnets and ev
en
more waste. Although there are many free IP’s to be had in a Class B network, future growth
must always be thought about and waste minimized to make the future growth that much more
easily confront able.




Appendix A


Assumptions



3 large colleges



4 subnets per building

3 buildings each




2000 students each

300 faculty each

Assume approximately 767/building


7

small colleges



5 subnets per building

1 building each

1000 students each

200 faculty each


Administration



1 subnet per building

10 buil
dings


one of which is a central computer facility

2000 faculty

Assume approximately 200/building


Residence Halls



2 subnets per building

4 buildings

2000 students

Assume approximately 500 students/building





















Appendix B


Subnet Classi
fication


3 large colleges



4 subnets per building

Building 1


128.100.0.0


128.100.3.0

Building 2


128.100.4.0


128.100.7.0

Building 3


128.100.8.0


128.100.11.0

Building 4


128.100.12.0


128.100.15.0

Building 5


128.100.16.0


128.100.19.0

Buil
ding 6


128.100.20.0


128.100.23.0

Building 7


128.100.24.0


128.100.27.0

Building 8


128.100.28.0


128.100.31.0

Building 9


128.100.32.0


128.100.35.0


7

small colleges



5 subnets per building

Building 1


128.100.36.0


128.100.40.0

Building 2


128.100.41.0


128.100.45.0

Building 3


128.100.46.0


128.100.50.0

Building 4


128.100.51.0


128.100.55.0

Building 5


128.100.56.0


128.100.60.0

Building 6


128.100.61.0


128.100.65.0

Building 7


128.100.66.0


128.100.70.0


Administration



1 su
bnet per building

Building 1


128.100.71.0

Building 2


128.100.72.0

Building 3


128.100.73.0

Building 4


128.100.74.0

Building 5


128.100.75.0

Building 6


128.100.76.0

Building 7


128.100.77.0

Building 8


128.100.78.0

Building 9


128.100.79.0

Buil
ding 10


128.100.80.0


Residence Halls



2 subnets per building

Building 1


128.100.81.0


128.100.82.0

Building 2


128.100.83.0


128.100.84.0

Building 3


128.100.85.0


128.100.86.0

Building 4


128.100.87.0


128.100.88.0


Free


--

128.100.89.0

-

1
28.100.255.0