Unsolved
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6 Posts
0
10529
VPN and/or Terminal Session drop sporadically when system is in use
Bizarre problem:
The system
* Precision 340
* On Board 3Com NIC
* 1gb RAM
* Windows XP Pro
* On Board display adapter (support 1024x768 LCD)
* Additional ‘VR Engine’ Display adapter (supports dual high-res monitors)
* Runs resource intensive medical applications
The problem: VPN and/or Terminal Session drop sporadically when system is in use
* Running Terminal Server client session to remote server via Microsoft VPN
* VPN and TS are both stable overnight when system is idle
* My PC Anywhere session to this machine is unaffected when the connection drops
* Other systems at the same site are unaffected
* Systems at other sites connected to the same VPN/Terminal Server are unaffected
Nothing of interest in the event log except pairs of 20158/20159 - VPN connect/disconnect (no reason)
Many thanks in advance for any thoughts on this…
jv
The system
* Precision 340
* On Board 3Com NIC
* 1gb RAM
* Windows XP Pro
* On Board display adapter (support 1024x768 LCD)
* Additional ‘VR Engine’ Display adapter (supports dual high-res monitors)
* Runs resource intensive medical applications
The problem: VPN and/or Terminal Session drop sporadically when system is in use
* Running Terminal Server client session to remote server via Microsoft VPN
* VPN and TS are both stable overnight when system is idle
* My PC Anywhere session to this machine is unaffected when the connection drops
* Other systems at the same site are unaffected
* Systems at other sites connected to the same VPN/Terminal Server are unaffected
Nothing of interest in the event log except pairs of 20158/20159 - VPN connect/disconnect (no reason)
Many thanks in advance for any thoughts on this…
jv
sentinel-master
345 Posts
0
October 7th, 2003 21:00
JV - sounds liek it could be an MTU issue
Have you adjusted the MTU size of your Ethernet interface from 1500 down to 1450 ( you have to allow extra room for the VPN (IPSEC headers ) otherwise you will get fragmented and dropped packets.
I.e you application wants to send 1500 bytes of useful data - this trundles down the stack - IPSEC inflates it 1540 due to extra headers....but frame size of ethernet is 1500 bytes (802.3 rules apply here) - so has to be dropped by NIC.
There should be an adjust MTU size in your VPN s/w - try turning it down to 1440 or 1450 bytes.
johnvlahos
6 Posts
0
October 7th, 2003 22:00
Thanks for the reply -good information. I believe we have it solved.
I found that QoS packet scheduler was installed on the VPN interface but not on the LAN interface. Hence the LAN was getting all the bandwidth the VPN was limited to 20%. So whenever a user surfed the web, grabbed a file from the network or anything else that was bandwidth intensive, the VPN connection was closed.
Now both interfaces have QoS, bandwidth limitations are removed and the problem appears to be gone.
Thanks for the help though.
Regards,
jv
jjjones3860
4 Posts
0
November 4th, 2003 22:00
Hi All - I have the same exact problem.
I have 2 laptops and one desktop Dell connecting through a TrueMobile Wireless 1170 Base station.
I connect through the internet via DSL in the back of the 1170 and then my desktop connects via hardwire, while the two laptops connect via wireless.
I connect to my work site via a VPN. This VPN drops sporadically and always enters a pair of events into the event log; stating the VPN was dropped, and because I have auto-reconnect, that the VPN was reconnected.
I am running WindowsXP Pro. But I do not understand the tech talk in the previous two replies for solving this. Please, please elaborate on how I can fix this annoying problem.
Thank you!
johnvlahos
6 Posts
0
November 5th, 2003 00:00
jjones...
Take a look at your network interface properties in control panel. Look for something called QOS packet scheduler and try disabling if it's there. By default it limits the bandwidth to 20% for the selected interface.
Hope this helps.