There's a somewhat simpler reg hack on Windoze. Set HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\EnablePMTUBHDetect to 1 This enables automatic 'Black Hole' router detection and triggers automatic MTU scaling. BTW, the 'Don't Fragment' Bit is on by default with Windows. Rob
How incredibly serendipitous. I just ran into this problem at work the yesterday. The service techs. for our digital radiology system came in and applied the latest service update. All of a sudden users weren't able to log in via their browser loaded Java client. Funny thing is, these guys spent 2 days trying to figure out the problem before resorting to asking "the network guy"... one of those pride things I guess.
Some quality time (15 minutes) with tcpdump (well, windump) showed the DF bit being set and repeated acknowledgment requests during the "hang". After a modest amount of investigation and a few phone calls the following was found:
1. a remote firewall blocking all ICMP (the admin won't change it) 2. a router somewhere in the path with a lower MTU requirement 3. a software upgrade forcing the DF bit to be set (developer won't change it)
Lowering the MTU on the client end fixed the problem; however, I need to get the registry hack distributed across ~500 desktop and all potentially have different interface descriptions in the HKLM/system/current control set/service/ ...what a PITA.
-- The information contained in this e-mail message is intended only for the use of the person or entity to whom it is addressed and may contain information that is CONFIDENTIAL and may be exempt from disclosure under applicable laws. If you read this message and are not the addressee you are notified that use, dissemination, distribution, or reproduction of this message is prohibited. If you have received this message in error, please notify us immediately and delete the original message. You should scan this message and any attached files for viruses. Axon Computertime accepts no liability for any loss caused either directly or indirectly by a virus arising from the use of this message or any attached file. - To unsubscribe from nznog, send email to majordomo(a)list.waikato.ac.nz where the body of your message reads: unsubscribe nznog