Hi

I have a dual boot Pentium4 system with Linux and Windows XP and a Linux box as router, the dual boot system's NIC and one of the router's NICs connected to a switch.
The P4 system has a onboard RTL8139 type RTL8100.
If i boot up Windows, networking is just fine, but when i boot Linux on the Pentium and try to access LAN or Internet , an unexplainable 50% packet loss occurs between the Pentium4 system and the router, in both directions and affects all kinds of communications; this means networking is possible but extremely slow compared to normal operation. The RTL8139 is identified correctly at boot and set up. (only apparently?)

As far as i could determine , in this case the packet loss is NOT caused by:

-IPv6 / IPv4 compatibility problems
-wrong IP configuration
-MTU size

perhaps its a matter of full/half duplex configuration, but since there's a switch between this seems less probable, or am i wrong?
i have tried different linux distributions boot cds, installations, kernel versions, compiled 8139too into the kernel or as module, the network controller is always recognized as rtl8139 type 8100 (which is perfectly right).

now what may be the cause for this packet loss?
any suggestions?

thx in advance

Does ifconfig show a larger number of errors? Is anything mentioned in the messages or syslog files? Are there any hints in the output of dmesg?

cheers and welcome to LinuxQuestions!

Jamie

well, there are no errors at all, no unusual messages. packets just dissappear.
i will start sniffing on all involved interfaces to check out if the packets themselves have some unusual characteristics that might cause some of them to be dropped somehow or whatever happens to them.