SUMMARY: le0: out of mbufs - packet dropped

From: Juan Nicolas Ruiz N. (
Date: Mon Nov 24 1997 - 12:25:34 CST

        First of all a great thanks to those who answered my question:

Glenn Satchell <>
Roy Culley <>
Mark Henderson <>
Reto Lichtensteiger <>
Joel Lee <>
Rich Kulawiec <>

I made the modification in the kernel suggested by Reto Lichtensteiger,
because was more specific than increasing MAXUSERS, and I will install the
patch suggested by Glenn Satchell (102430-02) sometime in the future. So far I
haven't had more hangs.

Checking netstat -i reported no errors, just some colissions.

The SS5 has 96 MB of physical RAM and 256 MB of swap, and it had (whenever I
checked) enough memory available.

My first idea was some kind of traffic flooding the SS (as Roy Culley
mentioned), but I haven't been able to verify it. Unfortunately, unplugging
the machine of the network didn't work.

Follows the original request and the individual answers

> I've received this error on a SS5 runing SunOS 4.1.4 a couple of
> times:
> le0: out of mbufs - packet dropped
> The machine simply hangs (even the keyboard lights doesn't change), there is
> no way to get in, and it doesn't answers to TCP, ARP or ICMP packets.
> The machine is DNS and NIS server, and Mail Relay.

From: Glenn Satchell - Uniq Professional Services

Try rebuilding the kernel and increasing the value of MAXUSERS. The
default is something like 16, try a value like 64. This tunes up many
kernel variables, sets sizes for structures and lists.

Also try this patch:

Patch-ID# 102430-02
Synopsis: SunOS 4.1.4: le patch that fixes sun4m ethernet hang problems
BugId's fixed with this patch: 1170392 1163300 1177296 1184046
Changes incorporated in this version: include the sun4c module
Date: Jul/26/95
From: Roy Culley <>

Whenever I have noticed this it was due to a host flooding the
network with packets addressed to or routed to the machine
that hangs. If you disconnect the host from the ethernet next
time it happens you should be able to login to the console as
root. Your problem is to find out where the packets are coming
from. I hope this is of some help.
From: Mark Henderson <>

You can increase the number of mbufs in the kernel - but first run
netstat -i and look at the error rate. A high error rate can cause
you to run out of mbufs on a busy machine.
From: Reto Lichtensteiger <>

Yup, mbufs are kernel data structures used to store chunks of network
data (incoming packets). Kernel memory numbers are fixed at compile time
under SunOS 4, so you will need to build a new kernel in order to
allocate a greater number of mbufs:

   /usr/sys/`arch -k`/param.h is the file:

       * MBPOOLBYTES gives the amount of virtual space to reserve for mbuf
       * storage.
      #define MBPOOLBYTES (2*1024*1024)

Change "#define MBPOOLBYTES (2*1024*1024)" to
       "#define MBPOOLBYTES (3*1024*1024)"

and recompile the kernel.

Note that this will, obviously, increase the amount of memory the running
kernel uses...
From: Joel Lee <>

Did you reboot and see if the problem reoccurs ? Looks like it's just
memory issue.
From: Rich Kulawiec <>

How much memory (and swap) do you have in this machine, and how much is
currently in use?

============================ Up The Irons ===============================
Juan Nicolas Ruiz | Reality is a nice place to visit but | I sure wouldn't want to live there.
Universidad de Los Andes |
Administrador de Red - RedULA | <My opinions are of my own, as it should be>

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