Date: Mon, 27 May 2002 12:09:44 -0700 (PDT) From: Christian Wittenhorst <wiwi@progon.net> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/38626: dummynet/traffic shaper: RED: max_th and min_th are limited to 32kbyes Message-ID: <200205271909.g4RJ9ip4048860@www.freebsd.org>
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>Number: 38626
>Category: kern
>Synopsis: dummynet/traffic shaper: RED: max_th and min_th are limited to 32kbyes
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon May 27 12:10:02 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Christian Wittenhorst
>Release: 4.6RC
>Organization:
progon network engineering
>Environment:
FreeBSD gandalf.kanti-zug.ch 4.6-RC FreeBSD 4.6-RC #14: Mon May 27 19:41:38 CEST 2002 wiwi@gandalf.kanti-zug.ch:/usr/src/sys/compile/yag i386
>Description:
The max_th&min_th parameters are limited to 32kbytes. dummynet scaled these values with 2**16 internally, so only 15 bits are significant (1 bit is lost for sign). This leads to the restriction to 2*15 bytes (32kb). The values handled to ipfw are NOT range checked, so if you use 80kb as an example you will even get a negative value for max_th or min_th.
>How-To-Repeat:
ipfw queue 9999 config queue 80kbytes pipe 10000 weight 4 mask dst-ip 0x000000ff red 0.002/16kbytes/48kbytes/0.1
ipfw queue list
q09999: weight 4 pipe 10000 80 KB 0 queues (1024 buckets)
RED w_q 0.001999 min_th 16384 max_th ***-16384*** max_p 0.099991
>Fix:
NOT A FIX, JUST A WORKAROUND (will allow 512kb for RED queues, which seems to be quite enough)
in /usr/src/sys/netinet/ip_dummynet.h replace
#define SCALE_RED 16
by
#define SCALE_RED 12
>Release-Note:
>Audit-Trail:
>Unformatted:
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