From: mike-newsgroup@-DELETETHISPART-.upcraft.com   
      
   Mark A. Shelley wrote:   
   > Dear VPN Fans,   
   >   
      
   BIG SNIP   
      
   > Any ideas on how to proceed in debugging this drop issue? Verizon won't help   
   > at all claiming that they don't support VPN unless you buya static IP and a   
   > business account. I tried to point out that VPN is just a protocol running   
   > over TCP/IP and that if they support TCP/IP and WindowsXP, then this is a   
   > problem that they need to look at.   
   >   
   > Is it possible that Verizon breaks the conection when they detect VPN   
   > protocols on home accounts?   
   >   
   > DIYGuy   
      
   1 of 2 problems I can think of.  MTU detection problem or packet loss.   
      
   1. The MTU autodetection on one of your routers is not working properly.   
      
   Try doing a ping test on both independently to one of the first few   
   routers along your path (use tracert to determine)   
      
   Try increasing the packet size of your ping packets and see if it gets   
   worse (it wont' get better), Start at 1000 bytes to verify it works,   
   Then try 1500 bytes which will fail, make sure you specify the do not   
   fragment flag.  Move down by 50 bytes until it works and then try to   
   zero in on the exact packet size that your connection will tolerate.  In   
   your router manually set the MTU size to the value you determined and   
   try your VPN tests again.  If it works you can try increasing this value   
   on the router by 20 and do another VPN test, this should be the optimum   
   value because the 20 bytes would be overhead caused by the TCP header.   
      
   2. You are experiencing packet loss on one or both of your connections.   
      
   Using ping again do tests to your ISP's routers and try to determine if   
   there is any packet loss on your connection.  Using larger packets will   
   help get more accurate results.  In the MTU problem you will always get   
   a packet failure with the do not fragment flag set when you encounter a   
   network limit.  With packet loss you will only get occasional failures   
   of some packets.  Make sure you do this test with no other sources of   
   traffic running on the connection or they will invalidate your results.   
     Connect a PC directly to the modem for this test before calling the   
   ISP.  You can start your testing with the router in place but once you   
   have determined that packet loss is present you must eliminate all of   
   your equipment that you can before the ISP will help you.   
      
   If you want to go to the last possible solution for fixing packet loss   
   on your end you would need to hookup your modem directly to the test   
   jack of your phone panel (if you have one) and completely disconnect all   
   the internal wiring and doing a test from there.  This will eliminate   
   internal sources of electrical interference on your lines from being the   
   source of the problem.  Also try different enthernet patch cords and   
   phone cords to the modem.   
      
   If you prove packet loss is present then call Verizon and report that   
   you have packet loss on your connection.  This is something they are   
   responsible for fixing, you can tell them you are trying to use VPN if   
   you like but there is no reason for them to deny you support if you have   
   identified the cause to be on their network.  I personally wouldn't even   
   mention it, a connection with packet loss is broken no matter what   
   application you are using it for.   
      
      
   --   
   WARNING!  Email address has been altered for spam resistance.   
   Please remove the -deletethispart-. section before replying directly.   
   Mike Drechsler (mike-newsgroup@-deletethispart-.upcraft.com)   
      
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