Help With Subnetting

computer g33k

I received an assignment in my CCNA class and I'm not sure where to begin. I have been giving I.P. address of block of 10.10.0.0/16. I have three networks ranging from 1000 hosts up to 2700 hosts. Also, I have 5 routers in between the three networks. I read through the chapter and I'm at a loss. Any help is appreciated.

https://docs.google.com/viewer?attid=0.1&pid=gmail&thid=132cc0b8d7e90454&url=https%3A%2F%2Fmail.google.com%2Fmail%2F%3Fui%3D2%26ik%3D5304523419%26view%3Datt%26th%3D132cc0b8d7e90454%26attid%3D0.1%26disp%3Dsafe%26zw&docid=fe864fea3545a7fa8fd6117102650901|26fbd9f86bab0482b3fa1072c3a8455f&a=bi&pagenumber=1&w=800

pham0329

What you're looking for is VLSM. Rather than us just working out the problem for you or giving you the answer, why don't you tell us where your at or where you're stuck at and we'll help fill in the blanks

CodeBlox

10.10.0.0 /16

The range for this block of addresses is :
10.10.0.0 - 10.10.255.255

Say you need a subnet that supports 1000 host, thats 10 host bits which leaves you with 22 subnet bits. In this case your mask would be 255.255.252.0 or /22

Say you need another subnet that supports 2000 host, that would require 11 host bits leaving you with 21 subnet bits. The mask would be 255.255.248.0 or /21

Say you need one more subnet that only requires 110 host, that would require 7 host bits leaving you with 25 subnet bits. The mask would be 255.255.255.128 or /25

Your subnets for your routers only need two IP addresses for the wan links. These will use a /30 or 255.255.255.252

Now to the picking of the subnets, you'll want to do your VLSM picking the largest ones first in the design(this is just my personal preference) as it easily prevents the problem of overlapping subnets.

The largest is the /21, the subnet for that one could be:

10.10.0.0 /21
The range for that subnet is 10.10.0.0 - 10.10.7.255

The next is the /22, the subnet for that one could be:
10.10.8.0 /22
The range for that subnet is 10.10.8.0 - 10.10.11.255

The next is the /25, the subnet for that one could be:
10.10.12.0 /25
The range for that subnet is 10.10.12.0 - 10.10.12.127

All that would need to be picked now is your subnets for your routers which only require 2 host each. You could use the following for your routers:
10.10.12.128 /30
10.10.12.132 /30
10.10.12.136 /30
10.10.12.140 /30
10.10.12.144 /30


You could use 10.10.0.0 /16 to summarize all of this.

edit: whoops let me go back end edit those mask