What Router- Network equipment will work well

Hi All,
Im considering setting up an asterisk PBX to replace an old PSTN based PSTN and I wanted to design the network to support this

I have attached a drawing of the proposed layout .
Blueface are the VOIP serivce provider.

Has anyone seen this type of configuration before

I’m hoping to use the fibre connection for the majority of the time and only really use the DSL when the Fibre is down

Does anyone know what type of router / firewall device will support this.

I’ve heard about problems with NAT and maybe this will be the biggest issue especially interms of a failover solution.

Also are there any security implications for snooping on the voice traffic.

Other traffic will aslo be present accross the networks such as VPN and general internet ( http,ftp,etc)

I don’t see you phones in the diagram. I guess they would be on the secondary physical network. That’s good as it should help ensure QoS for Voip. QoS is of utmost importance so you would want to use VLANs if you don’t have physically seperate networks.

Any firewall device that offers all of the services you mention should be ok. We use Nokia and Checkpoint. Once again QoS is important. Remeber you can only really manage traffic leaving your network, not necessarily the traffic coming in. The ISP controls that.

You can have NAT problems if Asterisk is behind a NAT firewall and the device you are trying to connect (typically a remote phone) is also. You can avoid this problem by giving Asterisk a public IP address. Or use the IAX protocol.

A ClarkConnect server running on some solid hardware will be able to do that.

QoS, failover support and you can add more NIC’s for more network interfaces.


Mine is running on a Dual Pentium 3 800mhz with 512mb ECC ram.

another bigone is sm00thwall, but i have no experience with it.