bill001g said:
I will assume you are talking about consumer internet connections and you are not using a commercial configuration where you are running a routing protocol and have a block of routable internet addresses assigned to you.
Using a actual router that can run a routing protocol with the ISP is really the only way you can accomplish what you want.
You have a number of problems. The main one when you have 2 internet connection is you have 2 different IP addresses. In your case if you have a voip call up the session is between these 2 ip. You can not suddenly change the ip in the middle of a call and expect it to not drop the call. Now the voice client could detect the failure and then register the new ip but you would have to reestablish the call.
This 2 ip concept is also a major problem for PC. You obviously can't use both IP to try to download a single file since the far end server would get confused and assume it was 2 different users. This is fundamental to how TCPIP works and can't be changed. In addition many web sites are made up of a number of servers many times at different locations. A game server is the most obvious but banks work that way too. The game server has a login authentication server that checks your credentials. It then passes control over to the gaming machine itself. If the connection for your pc would use 1 ip to talk to the authentication server and a different one to talk to the game machine it would be detected as a attack and blocked. This means you really need to always send all traffic for a particular machine over a single ip. So you would have to manually pick certain ip on one ISP and other on the other.
Now in theory you could split your users over the 2 ISP and if one goes down they could share the remaining one. The huge problem is what does "down" mean. Its not like the ethernet port powers off when you lose your ISP. Some routers can try to ping stuff but how much loss is too much and what device you ping does that mean the server is down or the internet.
You can only do so much with a dual wan router to really get what you need you need to discuss redundancy options with your ISP they likely have a number of suggestions on what they can offer you....for a price of course
Thanks for your reply, yes your correct we are using 2 ADSL Lines, unfortunately we do not get cable in our area yet and any other solutions would cost thousands unfortunately, this is why its vital to have the router set the way I said in original post, our ADSL Lines are only standard UK 20Mbps down and 1mbps up. Due to this its beneficial to have load balancing because we can push the combined speed to 35mbps down and almost 2mbps up which is far more beneficial.
I am aware that 2 ISPs = 2IPs however before the firmware upgrade I had basically the same settings I do now and the VoIP calls did not drop, they lagged for 2 seconds then the phones were sent through the other WAN port. The router can and does usually detect when one of the WAN links is down, granted the port wont power down but the router checks this itself.
the idea behind this plan was to introduce some good redundancy as our ADSL connections go down randomly before we had to half our devices between two connections which meant having to quickly change which routers devices were in when one went down, this is not practical.
I know there is a way to do what I need done. I know there are limitations and whatnot to battle with but the VoIP service can function using different IP's.