assigning Highest IP on each subnet is the default gateway to cooresponding VLAN

k31453

Network Diagram: https://www.dropbox.com/s/3cjw98iib5436af/1.png
I got 3 vlans
1st Management
required host : 15
Network ID: 192.168.100.0/27
Range : 192.168.100.0/27 - 192.168.100.31/27
Highest IP default-gateway: 192.168.100.30/27
2nd USER required host : 70
Network ID: 192.168.100.32/25
Range : 192.168.100.32/25 - 192.168.100.159/25
Highest IP default-gateway: 192.168.100.158/25
3rd Guest required host : 10
Network ID: 192.168.100.160/28
Range : 192.168.100.160/28 - 192.168.100.176/28
Highest IP default-gateway: 192.168.100.174/28
So in Level 1 switch i put IP default-gateway: 192.168.100.30
So in Level 2 switch i put IP default-gateway: 192.168.100.30
On router
f0/1.99 IP : 192.168.100.30/27
f0/1.10 IP : 192.168.100.158/25
f0/1.20 IP : 192.168.100.174/28
It doesnt work. So what I am doing wrong ?

gorebrush

Well...

192.168.100.158/25 is not a valid network.

Just because you need 128 hosts - you can't just slot it in the middle of a range.

The only two valid /25 networks in this case are: -

192.168.100.0/25
and
192.168.100.128/25

That's one hint for you...

mikerodriguez

^Pretty much that lol. If your going to do a VLSM you have to do it in order from the largest requirement to the smallest. For example:

Your requirements are the following:

- 1 Network for 15 hosts
- 1 Network for 70 hosts
- 1 Network for 10 host

You don't start with the smallest requirement, or the 2nd smallest for that matter. You start with the largest.

So your VLSM would be:

USER: Required Hosts - 70
192.168.100.0 - 192.168.100.127 /25
Highest assignable host address: 192.168.100.126

MANAGEMENT: Required Hosts - 15
192.168.100.128 - 192.168.100.159 /27
Highest assignable host address: 192.168.100.158

GUEST: Required Hosts - 10 /28
192.168.100.160 - 192.168.100.175 /28
Highest assignable host address: 192.168.100.174

Take a look at the Subnetting & VLSM/Summarization chapters in Todd Lammle's CCNA book, it'll help you out a LOT.

EDIT:
And you should add the corresponding default gateways to the hosts if you haven't already...