Controlling upstream on an assymetric connection


We are running a SBS 2003 server (this is not an SBS specific question,

therefore the post to this thread) connected to the Internet via ADSL connection. The setup is 2 NICs with ISA 2004 and the external NIC connected to a D-Link DI-604 SOHO router. We also have a remote office with only a single PC connected through VPN.

The problem is, our ADSL connection is 1.5Kbps for downstream, but unfortunately limited to only 96Kbps for upstream. Due to the limited upstream, it is very "easy" to "kill" the connection. For example, when

the Exchange server starts sending out large emails or a user uploads a

very large file the server becomes almost unreachable both to incoming connections, especially the incoming SMTP and remote VPN user's traffic. I know this is due to the basic design limitations of TCP/IP as a symmetric protocol, but I am posting to this group in hope to collect some ideas that can provide a possible solution. I need some way to prioritize the SMTP and VPN connection over the outgoing mail and web traffic (so that the server is always available to receive new messages and the remote worker is seldom disconnected). I know one of the possible solutions is QoS, but if so - how can I implement it in my enviornment? What hardware / software need to be purchased ? Is there an affordable solution to this problem ? (Keep in mind we are a small business with only 10 users).

Any suggestions would be greatly appreciated.



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Danny Liberty
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