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(?) The Answer Guy (!)


By James T. Dennis,
Starshine Technical Services, http://www.starshine.org/

(?) ifconfig reports TX errors on v2.1.x kernels

From Peter Bruley on Tue, 15 Dec 1998

(?) Answer Guy:

I have tried various 2.1x kernels every - once and a while to see how the new version is coming along. What I have noticed is errors being reported by "ifconfig" on the TX only (both ppp & eth). Do you know why ?

TX Error

(!) That's a good question. On the ethernet, I'd expect that most of them would be due to frame collisions. Basically they'd happen whenever any two cards on your segment tried to send dataframes at close to the same time. On the PPP link I'd expect them to be due to line noise.
However, I'm not sure and I don't know why you wouldn't see any RX errors. Are you saying that you only see these under the 2.1.xxx kernels? I can assure you that some errors are perfectly normal (under any kernel). Too many may indicate a flaky card (yours, or any other on your network segment), bad cabling (thinnet/coax is particularly bad --- also using cat 3 UTP and/or running any sort of cable too close to flourescent light ballasts and other sorts of transformers and "noisy" RF generating equipment).
On one of my systems (a 486 router, two 3c509 ISA ethernet cards, each on relatively short quiet cat 5 UTP segments, running 2.0.36) I have 0 errors in both the TX and RX segments out of about 200,000 packets routed. This is over an uptime of about 20 days. I picked that systems uptime and stats more or less at random (I'm using it's console as a telnet/terminal to get to my 'screen' session as I type this).
On another system (a 386DX33 with on 3c509 adapter, running 2.0.30) I see six million packets received and 26 thousand RX errors (no TX errors out of about 3 million packets transmitted). That's been up for 71 days.
I supposed we could commission a study to see if different ethernet cards, kernels and other factors produce wildly different statistics. But that sounds too much like a graduate project.

(?) 'ifconfig': TX errors

From Peter Bruley on Fri, 25 Dec 1998

(?) Hi: Jim

Thanks for your reply, sorry I'm slow getting back.

Here is a print out of my "ifconfig" after about 5 min. on the ppp connection to my ISP:

 lo    Link encap:Local Loopback
       inet addr:127.0.0.1  Bcast:0.0.0.0  Mask:255.0.0.0
       UP LOOPBACK RUNNING  MTU:3924  Metric:1
       RX packets:166 errors:0 dropped:0 overruns:0 frame:0
       TX packets:0 errors:24679 dropped:166 overruns:0 carrier:0 coll:0

 eth0  Link encap:Ethernet  HWaddr 00:40:05:60:71:DD
       inet addr:10.40.150.1  Bcast:10.40.150.255  Mask:255.255.255.0
       UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
       RX packets:288 errors:0 dropped:0 overruns:0 frame:0
       TX packets:86 errors:74789 dropped:507 overruns:0 carrier:0 coll:0
       Interrupt:10 Base address:0x7000

 ppp0  Link encap:Point-to-Point Protocol
       inet addr:226.186.100.56  P-t-P:226.186.100.249 Mask:255.255.255.255
       UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:576  Metric:1
       RX packets:156 errors:0 dropped:0 overruns:0 frame:0
       TX packets:0 errors:14836 dropped:135 overruns:0 carrier:0 coll:0

Here is are some of my software versions:


Kernel is 2.1.128
libc.so.5 => libc.so.5.4.44
depmod (Linux modutils) 2.1.121
ppp-2.3.5
net-tools 1.432

Things seem to work properly. (all network services) except for some utilities that report modem activity ie/ xmodemlights (http://www.netpci.com/~dwtharp/xmodemlights)

Note that my ethernet card is also reporting errors.

Now assuming that these are real errors; how come when I boot up into a v2.0.34 kernel all the errors go away (on both ethnet & ppp) and my xmodemlights utility works flawlessly ?

I have tried the v2.1.(85-131) kernel on apx 3-4 different boxes and I have observed the same problems.

I'm alone on this issue or do you know of others reporting the same problems ?

Peter

(!) I don't know if there's any problem here. However, I would check the kernel mailing archives and possibly (after downloading, installing and testing the 2.1.132 or later kernel) post a message to the kernel developers list to inquire about it.
I might be that the old 2.0.x driver wasn't reporting errors for your cards. They may have been buggy. It's also possible that they may have been driving your hardware slower, causing fewer errors, or fewer detections of errors. Of course it could be bugs in the latest drivers which we'd like fixed before we go to 2.2.
So, check with the kernel developers and possibly get onto the comp.os.linux.* newsgroups (networking or hardware) with this question to poll other users for their results.
[ In the "late breaking news" department, the kernels are starting to be called 2.2.pre so now is the time to start trying them out if you've been interested but afraid to go for a beta kernel. -- Heather ]

Copyright © 1999, James T. Dennis
Published in The Linux Gazette Issue 36 January 1999

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