Hello,
I've problems with receiving packets with an TQM8260 board on the SCC
10Mbit ethernet interface.
If I connect two tqm boards directly via an ethernet crossover cable and
send udp packets from one board to another the receiving CPM marks
1-15% of all packets with an crc error flag (this depends on packet
size and send speed). When I check the udp checksum of the received
packets this check only ails for approx 5-10% of the marked packets,
e.g.
Send packets in 5s CPM says CRC-Error[1] UDP checksum error
=====================================================================
6000 (512 bytes each) 591 / 9.8% 94 / 1.6%
4850 (512 bytes each ) 220 / 4.5% 34 / 0.7%
6000 (128 bytes each) 182 / 3% 43 / 0.7%
The faster the packets are send and the longer the packets are the more errors
are detected. If I send the packets with a rate <50 packets/s I got almost
no crc errors.
I'm very surprised over the errors, as I use a direct connection
between the boards and send only in one direction. In such a case I
would expect to get no errors. Can this be an EMI error of the
physical SCC ethernet interface of the tqm boards?
I also connected the tqm board via a switch to a PC 10Mbit ethernet
interface and got slightly smaller error rates, but they are still
there. If I use the FCC ethernet interface I don't get this problems.
Did anyone make similiar experiences or has an idea how this errors can happen?
I use the DENX linux-2.4.4-2002-10-06 (patched for RTAI linux 24.1.10)
and enabled full duplex mode in the SCC enet.c driver (without full
duplex I got also crc errors and lots of dropped packets).
Thomas Geffert
Footnotes:
[1] I got this value from the scc1 parameter ram field crcec.
--
Dipl.-Ing. Thomas Geffert
KEYMILE / Datentechnik Intercom GmbH
Frankenring 14, 30855 Langenhagen, Germany
Tel +49 (0)511 978197-669 / Fax +49 (0)511 978197-670
mailto:thomas.geffert@keymile.com / http://www.keymile.com
<<< Since 1st of October 2002 Datentechnik & Ascom Transmission serve
you as KEYMILE >>>
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
Check that all the flags are properly configured for full-duplex mode. I had
a similar problem with FCC ethernet where a bit was missing on the config
options.
-----Original Message-----
From: owner-linuxppc-embedded@lists.linuxppc.org
[mailto:owner-linuxppc-embedded@lists.linuxppc.org]On Behalf Of Thomas
Geffert
Sent: Friday, November 01, 2002 4:23 AM
To: linuxppc-embedded@lists.linuxppc.org
Subject: tqm 8260 scc ethernet crc errors
Hello,
I've problems with receiving packets with an TQM8260 board on the SCC
10Mbit ethernet interface.
If I connect two tqm boards directly via an ethernet crossover cable and
send udp packets from one board to another the receiving CPM marks
1-15% of all packets with an crc error flag (this depends on packet
size and send speed). When I check the udp checksum of the received
packets this check only ails for approx 5-10% of the marked packets,
e.g.
Send packets in 5s CPM says CRC-Error[1] UDP checksum error
=====================================================================
6000 (512 bytes each) 591 / 9.8% 94 / 1.6%
4850 (512 bytes each ) 220 / 4.5% 34 / 0.7%
6000 (128 bytes each) 182 / 3% 43 / 0.7%
The faster the packets are send and the longer the packets are
the more errors
are detected. If I send the packets with a rate <50 packets/s I got almost
no crc errors.
I'm very surprised over the errors, as I use a direct connection
between the boards and send only in one direction. In such a case I
would expect to get no errors. Can this be an EMI error of the
physical SCC ethernet interface of the tqm boards?
I also connected the tqm board via a switch to a PC 10Mbit ethernet
interface and got slightly smaller error rates, but they are still
there. If I use the FCC ethernet interface I don't get this problems.
Did anyone make similiar experiences or has an idea how this
errors can happen?
I use the DENX linux-2.4.4-2002-10-06 (patched for RTAI linux 24.1.10)
and enabled full duplex mode in the SCC enet.c driver (without full
duplex I got also crc errors and lots of dropped packets).
Thomas Geffert
Footnotes:
[1] I got this value from the scc1 parameter ram field crcec.
--
Dipl.-Ing. Thomas Geffert
KEYMILE / Datentechnik Intercom GmbH
Frankenring 14, 30855 Langenhagen, Germany
Tel +49 (0)511 978197-669 / Fax +49 (0)511 978197-670
mailto:thomas.geffert@keymile.com / http://www.keymile.com
<<< Since 1st of October 2002 Datentechnik & Ascom Transmission serve
you as KEYMILE >>>
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/