(no subject)

Gerhard Schaden (ges@liscon.com)
Tue, 1 Jul 2003 19:35:45 +0200


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Hi,=20

I've the following Setup

PC1
Linux PC kernel 2.4.21,
PCI Network card with realtek 8029=20

PC2
Windows 2k ( Terminal Server )
PCI Network card with realtek 8029=20
PCI Network card with realtek 8139

PC3
Windows 2k Terminal Server
PCI Network card with realtek 8139

Scenario 1:

PC1 and PC2 are connected via BNC and i use rdesktop to connect to the
terminal server, no problem
-------- --------
| PC 1 | | PC 2 |
|------| |------| =20
|-------------BNC--------------------|

Scenario 2:

PC2 gets a second Ethernet card rtl8139, routing is activated=20
PC3 is connected to PC2 via 100BaseT

-------- --------
| PC 1 | | PC 2 |-----100BaseT
|------| |------| |
|-------------BNC--------------------| |
|
--------
| PC 3 |
|------| =20

i connect to PC3 with rdesktop no problem

Scenario 3:

The BNC Network gets a 3Com 8 Port Hub with one BNC

-------- --------
| PC 1 | | PC 2 |
|------| |------|
|-------------BNC-----|--------------| =20
|
----- -------- =20
|HUB| -----10BaseT-----| PC 3 |
----- |------|

PC1 connects to PC3 with rdesktop with collision rate around 30% with
network utilization 30KB/s (70pkts/s)

But if

PC2 connects to PC3 with mstsc I get the same network utilization but NO
collision=20

It looks like, that the Linux Networking stack is faster but produces
more collisions, I've looked at the throughput with iptraf and it was
perfect, even if i added more PCs making some traffic with tcpspray.=20
The problem is that customers don't accept the high collision rate.

I tried to change nearly all components:

Different Motherboards, different NICs (3Com), different HUB, different
Kernel (2.4.18, 2.2.20, 2.2.12), different cables :), different
T-Connectors, different Resistors

Tuning the software:
Limiting incoming traffic with iptables, limiting incoming traffic with
ingress scheduling,=20

Any Ideas ?

-GES

----------------------------------------------------------------
LISCON GmbH http://www.liscon.com/
Gerhard Schaden ges@liscon.com
Leitung Forschung u. Entwicklung
=20
Europastrasse 8 Tel: +43 4242 214855
A-9500 Villach Fax: +43 4242 214855 99
AUSTRIA / EUROPE Mobil: +43 664 2333323
=20

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