Ethernet data corruption?
Hi,
The other night, my friend was sending me a video over the internet.
We tried http, ftp, and other protocols, using different download applications. It seemed to be corrupt, the same way, everytime. It wouldn't work, and had a different md5sum than the "good" version on my friend's computer. Eventually we got it working.
The same issue came up again today. I uploaded my Java project on my
professor's server and it gives me an error. However, if I load the html file with the Java applet in my web browser from this hard disk (instead of from the prof's), it works.
I am wondering if there is some sort of corruption going on here. I am
using Red Hat's 2.4.9-21 kernel.
Thanks
Kevin Breit
Quoted 10 lines
We tried http, ftp, and other protocols, using different download applications. It seemed to be corrupt, the same way, everytime. It wouldn't work, and had a different md5sum than the "good" version on my friend's computer. Eventually we got it working.
The same issue came up again today. I uploaded my Java project on my
professor's server and it gives me an error. However, if I load the html file with the Java applet in my web browser from this hard disk (instead of from the prof's), it works.
I am wondering if there is some sort of corruption going on here. I am
using Red Hat's 2.4.9-21 kernel.
At the physical layer ethernet has hardware checksumming, at the IP/TCP layer there is also checksum protection. That means that its almost certainly either
- Problem hardware/driver
- Some kind of broken transparent proxy server between the two boxes
What you really want to try is to upload the same files via different machines to find out which end is the problem, or if it is perhaps the link between them - eg does it go away only if both boxes are on the same LAN.
Alan
Review
Quoted 4 lines · Alan Cox
At the physical layer ethernet has hardware checksumming, at the IP/TCP layer there is also checksum protection. That means that its almost certainly either
(quoted diff) +0
-1- Problem hardware/driver
The hardware on this box _is_ quite poor. I do have a LOT of problems with Linux on here, so this could be it.
Quoted 6 lines
(quoted diff) +0
-1- Some kind of broken transparent proxy server between the two boxesWhat you really want to try is to upload the same files via different machines to find out which end is the problem, or if it is perhaps the link between them - eg does it go away only if both boxes are on the same LAN.
I'll try this from my desktop box tomorrow.
Thanks a lot
Kevin Breit
Quoted 13 lines · Kevin Breit
Hi,
The other night, my friend was sending me a video over the internet.
We tried http, ftp, and other protocols, using different download applications. It seemed to be corrupt, the same way, everytime. It wouldn't work, and had a different md5sum than the "good" version on my friend's computer. Eventually we got it working.
The same issue came up again today. I uploaded my Java project on my
professor's server and it gives me an error. However, if I load the html file with the Java applet in my web browser from this hard disk (instead of from the prof's), it works.
I am wondering if there is some sort of corruption going on here. I am
using Red Hat's 2.4.9-21 kernel.
Quoted 4 lines
Thanks
Kevin Breit
Every TCP/IP data packet is check-summed. Every Ethernet packet has a CRC. If you have data corruption it is caused either by a memory error or, most likely, you did not set the ftp data-transfer mode to binary set bin when you have the 'ftp>' prompt.
Also, text-files (Java Script) on DOS-based stuff (like windows) use both a '\r' and a '\n' at the end of each line. Unix/Linux uses '\n' only. I am pretty sure this is not a kernel issue.
Cheers,
Dick Johnson
Penguin : Linux version 2.4.1 on an i686 machine (797.90 BogoMips).
I was going to compile a list of innovations that could be attributed to Microsoft. Once I realized that Ctrl-Alt-Del was handled in the BIOS, I found that there aren't any.
Quoted 4 lines · Richard B. Johnson
Every TCP/IP data packet is check-summed. Every Ethernet packet has a CRC. If you have data corruption it is caused either by a memory error or, most likely, you did not set the ftp data-transfer mode to binary
set binwhen you have the 'ftp>' prompt.
I believed that I was uploading in bin mode anyways. As when I opened gftp, it said I was uising Binary mode.
Quoted 3 lines
Also, text-files (Java Script) on DOS-based stuff (like windows) use both a '\r' and a '\n' at the end of each line. Unix/Linux uses '\n' only. I am pretty sure this is not a kernel issue.
My professor's server is a Mac box. I doubt this is an issue anyways.
Thanks
Kevin Breit
Quoted 14 lines · Kevin Breit
Hi,
The other night, my friend was sending me a video over the internet.
We tried http, ftp, and other protocols, using different download applications. It seemed to be corrupt, the same way, everytime. It wouldn't work, and had a different md5sum than the "good" version on my friend's computer. Eventually we got it working.
The same issue came up again today. I uploaded my Java project on my
professor's server and it gives me an error. However, if I load the html file with the Java applet in my web browser from this hard disk (instead of from the prof's), it works.
I am wondering if there is some sort of corruption going on here. I am
using Red Hat's 2.4.9-21 kernel.
Generally, IP checksumming should catch this.
However, a number of ethernet cards do IP checksumming in hardware, so the kernel doesn't bother doing the checksum in software.
So if you are experiencing data corruption on the path between the NIC's FIFO memory, the PCI bus and main memory, it will not be detected. This is somewhat of a flaw in the whole idea of checksum offload, IMO...
What ethernet card are you using?
-
Quoted 3 lines · Andrew Morton
However, a number of ethernet cards do IP checksumming in hardware, so the kernel doesn't bother doing the checksum in software.
Interesting
Quoted 1 line
What ethernet card are you using?
I am using a built in (I think it's on the mobo actually) Intel EtherExpress 10/100 Pro:
eepro100 17680 1
Thanks for the help
Kevin Breit
Quoted 5 lines · Kevin Breit
Quoted 3 lines · Andrew Morton
However, a number of ethernet cards do IP checksumming in hardware, so the kernel doesn't bother doing the checksum in software.
Quoted 8 lines
Interesting
Quoted 1 line
What ethernet card are you using?
I am using a built in (I think it's on the mobo actually) Intel EtherExpress 10/100 Pro:
eepro100 17680 1
Oh well, there goes that theory. eepro100.c does software checksumming.
-