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Date: Mon, 3 Mar 1997 06:43:06 -0800 (PST)
From: rtm@eecs.harvard.edu
To: freebsd-gnats-submit@freebsd.org
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Subject: kern/2857: DE500 board exhibits capture effect
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>Number:         2857
>Category:       kern
>Synopsis:       DE500 board exhibits capture effect
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Mar  3 06:50:01 PST 1997
>Last-Modified:
>Originator:     Robert Morris
>Organization:
Harvard University
>Release:        2.1.5
>Environment:
FreeBSD punish.uun.org 2.1.5-RELEASE FreeBSD 2.1.5-RELEASE #0: Tue Feb  4 16:42:28 EST 1997     rtm@punish.uun.org:/usr/src/sys/compile/PUNISH  i386

>Description:
I have some DE500 boards running at 10 megabits with FreeBSD 2.1.5.  I
believe I've run into the problem that the 21x40 capture effect
resolution was meant to solve: if one host is doing a long file
transfer, other hosts drop outgoing packets due to excessive
re-transmits. When I turn on CAPTREFFCT and ENHCAPTEFFCT in if_de.c,
the problem goes away (for one greedy host, anyway; multiple greedy
hosts still cause problems).

FreeBSD says this about my cards:
de0 <Digital DC21140 Fast Ethernet> rev 18 int a irq 10 on pci0:12
de0: Digital DE500 DC21140 [10-100Mb/s] pass 1.2 Ethernet address 00:00:f8:02:36
:c5

>How-To-Repeat:
Transfer a file between two DE500 hosts at 10 megabits.
Ping between two other hosts on the same net.
Observe ping times of tens or hundreds of milliseconds
rather than the expected 1 or 2.
>Fix:
Turn on TULIP_CMD_CAPTREFFCT and TULIP_CMD_ENHCAPTEFFCT in
tulip_dc21140_de500_media_select in if_de.c. I have done this
and observed no ill effects. I have not tried this with
other boards or at 100 megabits.
>Audit-Trail:
>Unformatted: