[closed] Seeing traffic destined for another network, hitting all machines

Hi,

We have a site that is set up with 2 subnets, 192.168.50.x which is used for data and 192.168.60.x which is used for voice, both use a 255.255.255.0 mask. These are NOT VLANs, they are purely separate subnets however they traverse the same switches so consequently are part of the same broadcast domain.

The problem we are having is that when users are using the phones, all of the UDP voice traffic from the 192.168.60.x network is hitting all machines on the 192.168.50.x network. For example, on a machine on 192.168.50.22, we see traffic sourced from 192.168.60.10 (the PBX) destined to 192.168.60.26 but it is hitting all machines? Interestingly, the source MAC address is the default gateway of the PBX server however the destination MAC address is another device related to the PBX.

Could anybody shed any light as to what is going on here? I suspect the default gateway (which is the same for both subnets, it is just configured with 2 LANs) is rerouting the traffic back to the 192.168.50.x subnet, but why is it hitting all the machines!? It reaping havoc on the network and causing all sorts of network connectivity issues...

Any guidance would be much appreciated.

Regards,

Jonathan.