Branch office tunnel nailed up ???

I am wondering if anyone has a solution for this. I have 3 sites around our city that all have a cable modem connection and are statically addressed. They then connect to a Nortel Contivity 221 4 port VPN router, and there they are setup to make the connection with our main site VIA VPN through our Contivity 1750.

On my Contivity 1750 the group that these branch tunnels are in I have Nailed Up Enabled.

On the contivity 221 I have Keep Alive enabled.

However the connection is not kept alive continuously. I would like the connection to be continuous without any breaks.

Right now it seems to work this way, if there is traffic between the branch and the main VPN then the connection gets activated for some much time, lets say 3 or 4 minutes. So then I can go to a command prompt and PING the remote location of lets say: 192.168.4.10 and I get replies right away.

However if no one is at the branch office the connection seems to drop, because when I do a ping of 192.168.4.10 I get 2 or 3 time- outs and then I get replies. After this the connection stays up fr a few minutes before going down again due to no traffic.

I want this connection to be up all of the time, traffic or no trafic, anyone know what I need to do?

interesting question, I am doing the exact same thing and I get intermittent results. Sometimes I get instant results and sometimes I get 1 or 2 time outs before a reply.

One thing I have done that has helped this somewhat is we have a s/w that monitors the connectivity of the remote sites and sends an ICMP (ping) from our network through our 2700 to the 221 at the far end. This seems to stabilize the link somewhat but keep in mind that we are going through the public N/W.....

The product is called Link Analyst and is made by Network Instruments. The time between pings is configurable. I have mine set at every 59 seconds.

I will follow this post to see if anyone has any more technical suggestions.....

John