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VPN Dropouts

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7 replies

by tpcosmo

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I have three Windows 2000 servers connected with a VPN over T1. The traffic over the VPN mainly consists of AD replication, Exchange e-mail, and very small file transfers, and two remote desktop users. Everything works great until the usage gets just a little heavier. For instance, if one user is connected and using a remote desktop session, and I try to open a Terminal Services session, the VPN will dropout for 5-10 seconds, and we both get disconnected. I'll do a persistent ping of the remoteserver, and it works great. I open the TS session, and in under a minute the VPN drops, my ping gets no response, and my TS session is interrupted. A few seconds later, the ping gets a response, and all is well. I can ping the remote server all night and lose maybe 1-10 packets. With no traffic during work hours I still have practically no lost packets. BUT get two users on at the same time and it drops.
Does anyone know why this might happen. Would it make sence fo have each user make their own VPN connection? Is there a limit to the traffic a VPN can handle? Thanks.

7 replies

by acattr

Devices:
Check your VPN devices on both sides. they should have logging that will tell you why the connection is dropping. Call your VPN device manufacture. Try another vpn device on each end. You can easily setup two windows 2000 boxes to use Routing and Remote Accees and PPTP.

Connection from Point 1 to 2:
If and only IF ICMP is allowed you can try to ping the external internet IP address of the remote vpn box and see if the failures happen at the same time as your internal vpn pings. If they do, you have connectivity problems between your ISP and thier ISP. YOu can use tracert.exe to ping the other vpn box to see where the problem lies. tracert will tell you exactly at what ISP router the connection is failing.

by tpcosmo

Thanks for the reply. The VPN devices are both Windows 2000 Servers. Unfortunately I dont have the resources to try different devices at each end.
I dont think it is an ISP problem. In my system event log I get an event that says 'The reason for dicsonnecting was user request' But the user is a dedicated account for the VPN, and it didnt request a disconnection.

Any other ideas?

Thanks a lot!

by acattr

right click the vpn interface under RRAS, select properties, go to options tab, under connection type select "persistent connection"

by tpcosmo

Thanks for the quick response. You may just be onto something. My WAN consists of three offices, say 'A' , 'B', and 'C'. We have VPN connections pointing from each location to the other two. 'A' connects to 'B', and 'C'. 'B' connects to 'A' and 'C'......

On the 'A's interface to connect to 'B' its set as a persistent connection. At the other end, 'B's interface to connect to 'A' is set to persistent also. I was under the impression that one should be set to persistent, and the other to demand dial. Do you have an opinion on these settings. I have NO problems with my 'A' to 'C' connections and they are set one way persistent, and the other way demand dial.

I hope this isnt confusing.
Ill give you the points after I see your response.If I award them now, you wont be able to post a follow up.

Thanks again!
Tom Costello

by acattr

I fully understand your setup. I've implemented one similar to this. You definately need to enable it as persistent. You only use demand dial if the connection is too expensive to leave open, like ISDN or long distance dialing. There is no need to use demand dial over vpn. Try it. Email me to follow up. wwwacny@yahoo.com

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