Consider my local network infrastructure map:


I've a device with a Virtual Machine that acts as a QOS manager/firewall to filter and prioritize traffic with complex rules that my main router cannot manage.

I would know if it's possible to route all connection to ZeroShell VM only when it's up and running, otherwise keeping the main router as default route for internet.

I need it because sometime the Firewall/QOS machine can go offline/under maintenance but i need that all devices continue to have internet access without manually change IP

  • Where is the Internet router connected? I don't see it in your diagram. – Ron Trunk Jan 26 '15 at 16:39

you should check out VRRP or HSRP (when using Cisco)

http://en.wikipedia.org/wiki/Virtual_Router_Redundancy_Protocol http://en.wikipedia.org/wiki/Hot_Standby_Router_Protocol

In a nutshell:

2 routers will check availability, when the main disconnects, the backup takes over. These routers need to be in the same subnet doh, using 1 IP per router and 1 shared IP.

This shared IP is your default gateway.

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  • Unfortunately my main router seems not implement both features. So i've thought using the routes and metrics: if the route to firewall is not available, then choose that with "higher metric". But i don't know if is it doable – Giuseppe Ronca Feb 3 '15 at 8:57
  • Metrics you can use on your WAN part, but to provide a single IP to the LAN part, you need these protocols. A client doesn't have prioritisation. – Bulki Feb 4 '15 at 7:14

You could use a routing protocol like BGP and create a relationship with your router. Give your router preference to the VM, and let the routing protocol handle it.

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