SUMMARY: Excessive collision patch

From: Charlie Mengel - LGI (
Date: Tue Jul 27 1993 - 20:35:12 CDT

Hey Folks -

Thanks for the quick response! The patch I was looking for was # 100768.
Randy Ott of Logicon on beatiful Bellvue, WA sent the README, so I will
in my summary.

The specific patch was designed to work with SS2, but you will notice in
the README that sun4m is supported.

--- cut here ---

Patch-ID# 100768-01
Keywords: collisions, repeaters, PC
Synopsis: 4.1.1;4.1.2;4.1.3: Extremely high collision rate when using SS2 servers and repeaters
Date: 13-Oct-92
SunOS release: 4.1.1, 4.1.2, 4.1.3
Unbundled Product: Not Applicable
Unbundled Release: Not Applicable
Topic: Network performance with SS2's.
BugId's fixed with this patch: 1075049

Changes incorporated in this version:

Architectures for which this patch is available: sun4c,sun4m

Patches which may conflict with this patch: 100330

Obsoleted by:

Files included with this patch: if_le.o

Problem Description:

In a multi-vendor network (with PC's,etc),collision-rate was going
sky high when the first SparcSation-2's were installed as servers.
Collision rate was around 1-3% and goes to 30-50% when connecting
SS-2's on the net.


1) mv /sys/sun{4c,4m}/OBJ/if_le.o /sys/sun{4c,4m}/OBJ/if_le.o.fcs
        cp sun{4c,4m}/4.1.{1,2,3}/if_le.o /sys/sun{4c,4m}/OBJ

2) In case of sun4m and 4.1.2 also:
        cp sun4m/4.1.2/atom.h /sys/os

     Please Refer to the System and Networking Administration Manual
             section on building and installing a custom kernel.


1) The patch should be installed on ALL Sparcstations on the
   network for obtaining lowered collision rate.

2) When the network utilisation is high for ex > 30%, this patch will
   NOT be effective - since the load is high and high collision rate is
   inevitable. This patch is NOT a cure-all and should be used as a
   last resort

3) There is a possible performance hit with this patch installed-
   though this was found to be nominal even at high CPU utilisation.

4) This patch is more effective in a Multi-vendor environment as against
   a Sun Workstation only network because the original problem was that
   the slower machines ,such as the PC's, could not get on the network
   and used to time out.


The patch for the "le" driver is designed such that "le" interface switches
from "back-to-back packet" mode to "packet-at-a-time" mode at a collision rate
of 10 % by default (lecollhi = 100 Decimal). When the collision rate drops
below 5% by default (lecolllo = 50 Decimal), the "le" interface switches
back to "back-to-back packet" mode.

--- END ---
Thanks to all those who responded:

 Randy Ott <randy@sisdbell.Logicon.COM
"Harold A. Miller" < (Joel Shandelman

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