Putting Two Different Networks on the Same Subnet Mask

This might get you started....

http://serverfault.com/questions/418522/is-it-possible-to-connect-2-networks-with-same-ip-range

Hi,

There's a quick and dirty way of doing this and there's a more expensive but technically better way.

Here's the quick and dirty way:

1. Put all of your devices on the same IP subnet - ie 192.168.1.0/24.

2. Lay some fibre between the buildings. If you need gigabit between the buildings then you need to think about the type of fibre you are using. If it is less than 550m then you can use OM3 multimode fibre, if it is further you will need OS1 singlemode fibre. If you only need this for voice, you would get away with 100M, in which case you can go for 2Km on OM3. The costs of the fibre are about the same, but you will pay more for SFPs in the switches for singlemode.

3. Get yourself a couple of network switches with SFP uplink ports. Buy some SFPs of the correct fibre type (SX for OM3, LX for OS1).

4. Plug everything together and you should have comms.

The downside of this approach is that the fibre link between the two buildings is a pinch point and if you are sending both voice and data between the two buildings, it is quite likely you will run into voice quality problems due to the link being filled up with data.

The better and correct way of doing this is as follows, however unless you are pretty familiar with data networking, this is probably going to be difficult for you to do without help.

1. Create VLANs to split up the network traffic. Eg Site A would have a Voice VLAN = 10, a Data VLAN = 20. Site B would have a Voice VLAN =30 and a Data VLAN = 40.

2. Different IP subnets would be allocated to the VLANs. Eg VLAN 10 = 192.168.10.0/24, VLAN 20 = 192.168.20.0/24, etc.

3. A Layer 3 switch would be implemented on Site A to route between the VLANs. Prioritisation would be set in the L3 switch to prioritise the time sensitive voice traffic.

4. The L3 switch would have a fibre SFP in it for the Site B link and a normal (L2) switch would be installed on Site B for the other end of the fibre link. The L2 switch would also need to be capable of prioritisation of the voice VLAN.

This is a much better solution because it keeps broadcast and multicast traffic off the fibre link and segregates and prioritises the voice traffic.

I hope that helps.

Yout can bridge two buildings with wireless bridges. If you don't put something decent in, it will be nothing but trouble with reliability and voice quality problems. How many handsets ate you supporting?