splitting/subnetting IP range for VLAN

[robertsouthgate]

Hi,

I have been given an external range, say 1.1.1.168/29 giving me usable or 1.1.1.169-174, so 6 useable IPs, although one will be used for the gateway, so really only 5 (or 4 as below).

I am trying to split this up into 2 separate Vlans on a Cisco 1921. so that each VLAN can have at least useable 2 IPs (excluding the gateway).

How can I do this or is it even possible?  or would I simply need a bigger range to do it?

Can i somehow have x.x.x.169 170-171 and then x.x.x.172 173-174 for the other?

[Marcel Zehnder]

Hi Robert

You can split your /29 in two /30

x.x.x.168/29 ---> x.x.x.168/30 & x.x.x.172/30

VLAN A x.x.x.168/30

x.x.x.168 = Subnet

x.x.x.169 = Usable IP

x.x.x 170 = Usable IP

x.x.x 171 = Broadcast

VLAN B x.x.x.172/30

x.x.x.172 = Subnet

x.x.x.173 = Usable IP

x.x.x.174 = Usable IP

x.x.x.175 = Broadcast

So you will have 2 IPs per subnet, one for the router, 1 for a client - if you need two client-IPs per subnet you need a bigger range.

HTH

[robertsouthgate]

Hi Marcel,

Yes this is what I thought.  I need at least 2 client IPs, so have had to get a bigger range.

Thanks