Slow Remote Desktop Sessions in Specific Circumstances
I'm encountering a very unusual problem. I have a machine that has Vista (originally an upgrade install, is now a clean install) RTM on it. Everything works great except specific instances of remote desktop connection.First, I'll try to (briefly) overview the scenario. I'm a consultant and have servers at the office and routinely take care of customer servers as well, so I am using RDP constantly. I have servers at the office that are in our LAN (our own internal servers), servers that are in a DMZ, and other servers at various customer sites. At the office we use a CheckPoint firewall (LAN\DMZ\WAN setup.)Whenever I use Vista's RDP to connect to a server that crosses a boundary on the CheckPoint box, the connection is VERY slow. If I connect to a server using Vista's RDP that does not cross the CheckPoint boundary it runs without incident in "full" speed. To isolate the issue completely, I tried a variety of different scenarios. I can connect with RDP in WinXP (I reformatted the laptop with XP) and it connects through the CheckPoint boundaries with no issue. I tried using RDP from a Mac outside of the office coming in crossing the CheckPoint boundaries and it worked fine as well. If I establish a VPN session with a LAN server, RDP works fine - just for the LAN servers - but when I try to access a DMZ server via RDP, it is still slow. So basically through pretty extensive testing (laptop both inside and out of the office, trying all combinations of connections; reformatted with clean XP Pro works fine, reformat with clean Vista, remains slow; any other machine works without incident - this ONLY affects the Vista machine ONLY when it crosses a boundary in the CheckPoint.)Does anyone have any ideas or guidance? I've been working on some packet captures thinking this could be a problem with packets either being lost or mangled by CheckPoint when coming from Vista (due to the new security checking? - the bit about it partially working when VPNed in makes me think this) but so far haven't been able to nail anything concrete.Thanks in advance - Doug
November 24th, 2006 8:33am

Having the exact same problem (I think). Running RTM Vista, and can't get a good RDP connection to my office. RDP to anything on my home LAN works just fine, but when I cross the firewall, the whole thing breaks. Please post if you have any luck.
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December 4th, 2006 4:39am

Had same problem. Issue was with our Cisco router and the IOS Software.The supported versions are Cisco IOS Software Release 12.3(15) or later. http://www.cisco.com/en/US/products/sw/secursw/ps1018/products_tech_note09186a0080743212.shtml The Microsoft Windows Vista OS enables the TCP Window Scaling option by default (previous Windows OSes had this option disabled). The TCP Window Scaling option is described in RFC 1323 (TCP Extensions for High Performance), and allows for the device to advertise a receive window larger than 65 K than TCP originally specified. This is useful in the higher speed networks of today, where more data can be outstanding on the wire before it is acknowledged. This slow performance, or dropped TCP connections is caused by some versions of Cisco IOS Firewall software not supporting the TCP Window Scaling option. This causes it to have a much smaller TCP window than the endpoints actually have. This causes the Cisco IOS router that runs the IOS Firewall feature set to drop packets that it believes are outside the TCP window, but which really are not.
December 10th, 2006 12:12am

I am having the same issue. All my clients use Sonicwall firewalls and this is quite a problem. Any other solutions?
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January 3rd, 2007 12:22am

I was having the same problem, and this fixed it for me. It seems that Vista enables TCP Window Scaling by default (disabled on XP by default). To disable this *feature* run these from an Administrative Command Prompt: netsh interface tcp set global rss=disablednetsh interface tcp set global autotuninglevel=disabled
January 15th, 2007 6:46am

A very simple but useful article on TCP/IP stack, autotuning and receive window: http://www.chapterzero.co.uk/articles/windows-vista-slow-network-issues.aspx Cheers!
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August 16th, 2007 2:30pm

Disabling these options was very helpful for me too!! Thanx
February 4th, 2008 4:04pm

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