Question about sub net design 1

[patrussell]

I realize there is a lot of info here on using subnets and I have learned a lot reading them, but I have not seen anything that helps with my scenario.

I am trying to divide one physical network into multiple subnets but need each subnet to be accessibe from the "main" network AND have access to the "main" network. I am using 192.168.xx.xxx for my IP scheme with a subnet mask of 255.255.248.0 on all the hosts in the subnets.

My problem is getting the subnets to ping the main network where I have a PC that will act as a data warehouse. There is no router in the network. The IP address of the data PC is set for 192.168.8.1 with a subnet mask of 255.255.0.0.

Is what I am attempting possible using only subnet masking? Thanks for the help.

 

[Ntr0P]

You need a router to route between subnets. Another option is to use a VLAN if your switch is capable. That would isolate your traffic, and you can create a trunk link to the server so all workstations can access the server.

If neither of the above is a possible solution, you can add an IP for each subnet to the interface of the server. Not the greatest solution, but it would work.

 

[patrussell]

Thanks, not the answer I was hoping for though. I'll look into the VLAN and router options.

 

[StarTAC]

if u don't have a router, u could use a Linux server and set it up as your router...

although i see u are subnetting a Class B network.... isn't that quite large.. wouldn't Class C subnetting be easier for u.....?...

good luck..

 

[pansophic]

patrussell,

It is extremely bad form to mask a subnet over its network size. A 192.168.x.x network is, by definition, a class C network (255.255.255.0). If you want a larger network size, you should choose a class B or class A private network address, 172.16-31.x.x and 10.x.x.x respectively.

Some network equipment will not allow you to create a netmask that is too large for the network number, and it is possible that you are experiencing this first hand.

According to the netmask you have assigned, 192.168.8.x, 192.168.9.x, 192.168.10.x, 192.168.11.x, 192.168.12.x, 192.168.13.x, 192.168.14.x and 192.168.15.x are all on the same subnet (really a supernet). All of these networks are accessible to the server directly because of its class B subnet mask.

But I fail to see what you are attempting to accomplish. Because all of your hosts are on the same physical network, you aren't really accomplishing anything. Every host sees every packet, it just may or may not respond to it.

If you are really interested in subnetting like this, I would recommend that you simply create secondary addresses on the server with addresses that fall into the correct subnet ranges (as determined by your subnet mask). That will make the server available to everyone, but not allow hosts on each of the subnets access to the other subnets directly.

For instance:

LAN1 172.16.0-7.x 255.255.248.0
LAN2 172.16.8-15.x 255.255.248.0
LAN3 172.16.16-23.x 255.255.248.0
LAN4 172.16.24-31.x 255.255.248.0
LAN5 172.16.32-39.x 255.255.248.0

Sever 172.16.0.10 255.255.248.0
172.16.8.10 255.255.248.0
172.16.16.10 255.255.248.0
172.16.24.10 255.255.248.0
172.16.32.10 255.255.248.0

This can be done with a single NIC card in the server, and logically segments the physical network. As long as you do not turn on IP forwarding on the server, there won't be any direct connections between clients.
pansophic