FS#3722 - Packets sized >1568 bytes cannot be received

Attached to Project: Arch Linux
Opened by Anton Kuzmin (Selecter) - Friday, 06 January 2006, 22:08 GMT
Last edited by Tobias Powalowski (tpowa) - Friday, 06 January 2006, 22:26 GMT
Task Type Bug Report
Category Kernel
Status Closed
Assigned To Judd Vinet (judd)
Architecture not specified
Severity High
Priority Normal
Reported Version 0.7 Wombat
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Motherboard: http://www.asrock.com/product/product_939S56-M.htm
In windows the networkcard is called: "sis190" though...
Its chipset has been supported since kernel 2.6.14 - that's why we choosed archlinux to install (it has 2.6.15).

The strange bug we have been experiencing is that we can't get (but we can send) network packets sized > 1568 bytes (not sure in this number). We tested it through ping command with -s flag. That's why the majority of the network services don't work. google.com works perfecly though because it always sends back 64 bytes packets.

Some ftp mirrors didn't work at all. We tried ftp.estpak.ee without success. But ftp.belnet.be worked good... But...
We could download packages (pacman -S xorg) very slowly (15kb/sek) and connection was constantly stalling from time to time with the same time intervals. We could ping all internet services, we could nmap all the services... but we couldn't get connected to the majority of them. wget, firefox etc were always waiting for response.

Please upstream this bugreport if neccessary.
This task depends upon

Closed by  Judd Vinet (judd)
Sunday, 08 January 2006, 22:49 GMT
Reason for closing:  Not a bug
Comment by Anton Kuzmin (Selecter) - Friday, 06 January 2006, 22:11 GMT
>We could download packages (pacman -S xorg) very slowly (15kb/sek) and connection was constantly stalling from time to time with the same time intervals

And we had to restart 'pacman -S <package>' to continue downloading...
Comment by Judd Vinet (judd) - Saturday, 07 January 2006, 21:29 GMT
Okay, so which packet size has been limited to 1568 bytes? Incoming IP packets, or incoming Ethernet frames?

As far as I understand, the ethernet module is only directly responsible for handling Ethernet frames, since the IP packet processing occurs later in the stack and is (should be) processed in the IPv4 stuff, not the sis190 stuff.

What is the MTU set at for your ethernet card? It can be found in the output from ifconfig.
Comment by Anton Kuzmin (Selecter) - Sunday, 08 January 2006, 16:37 GMT
Mtu was 1468... He set mtu to 1400 and it fixed the issue. You can close the bug. But I don't get it... Who should handle mtu value anyway? A user or distribution?
Comment by Judd Vinet (judd) - Sunday, 08 January 2006, 22:49 GMT
Well, an MTU varies depending on the network and/or network card, so that's user-specific. For example, the standard MTU of 1500 works fine with my network/card here, as it does for almost everyone.

MTU can be set in rc.conf for that interface's ifconfig line, which is also system/user-specific.

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