Eth0 Nic reported RX Packets errors and drops

[Jorge Cocomess]

RX packets:3891851066 errors:435 dropped:435 overruns:0 frame:0

No problems on the TX packets though;
TX packets:4334435256 errors:0 dropped:0 overruns:0 carrier:0

I am running RHAS 3.0 with Kernel 2.4.21-15.EL

Thanks,
J

[Steven E. Protter]

Shalom Jorge,

Dropped packets can be due to firewall reject, actual local network problems or problems with any point between your system and the system trying to connect.

If there are no other problems, its probably not worth a time intensive investigation. That is especially true if the system is exposed to the Internet.

SEP

[Ivan Ferreira · Accepted solution]

Errors and dropped packets may be also because a bad network speed negotiation between the network interface and the switch. Try configuring manually the speed for both. Use ethtool on linux. Check your switch documentation about how to set the speed and duplex.

[rick jones]

Do firewall drops actually appear in ifconfig stats?

Anyway, it might be good to look at the link-level stats. ethtool -S if you have it. That could give more detailed information about the drops if they are at the NIC/driver level

[Bill Thorsteinson]

Likely a duplex problem on the swithch end.
If the server is hardcoded to full-duplex
with a fixed speed the swithc will auto
negotiate to half duplex.
It will then stop sending packets if the server sends data while the switch is sending
data.
Try setting the server to auto negotiate.

Quick fix may be unplug the cable for a
few seconds and then plug it back in.

I have also seen Cisco switches silently
drop to half duplex even if they are
hard-coded to full-duplex if the server
loadd the driver and doesn't configure it
right away.

Recommended solution is to get the swich
set to auto-negotiate duplex.

Alternatively, this can be fixed by removing
the driver from the /etc/modules list, if
it isn't built into the kernel. Use
modules.conf to load the driver when you
try to configure eth0, or load the
module when you configure the interface.

[Alan_152]

Check duplexing, speed, autonegotiation, physical cable, and firewalls for issues. You may also want to change out NICs and switch ports, if applicable.

[rick jones]

I would have expected at least a few TX errors if there was a duplex issue, although I _suppose_ if the transmitting side was FDX it might not record the FCS errors on its transmitted packets.

[Jorge Cocomess]

Thanks so much for the advice.

I think I'll try to set flow control at the NIC and the switch first. Second, I will try to tune the kernel buffers to handle more packets.

I will let you all know the result in a few days.

Thanks,
J