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Date:      Fri, 3 May 2002 01:35:02 -0500
From:      "Budec" <budec@qwest.net>
To:        questions@freebsd.org
Subject:   Networking Buffers
Message-ID:  <NGBBIILBAKIFGHHCHOHPKEBLCOAA.budec@qwest.net>

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I am currently running FreeBSD i386 4.5 Stable and having some network
issuses.

The machine is a 300 Mhz, AMD K6-2 with 512 meg ram and 2 intel ether net
pro nicks.
Has dual 100 Gig WD IDE drives, and one 4 gig samsung HD.

The main purpose of this box is for firewall between networks and file
server.

The network traffic on it is quite high, it currently rsyncs/robocopies to 4
other servers
on the same network over a 100mb connection though smb/nfs and currently
routes all traffic between
2 network, each with 10+ workstation that require a high amount of bandwidth
(real time network application + vnc sessions + file copies).
The box seems to keep up fine without network delays, but sometimes one of
the nics just freezes.

The issuse I am having on it, is it seems I am "blowing out" one of the
nics.
I am sure this FreeBSD related, because this box use to run W2K with a
higher
network load and didn't expeirence any issuses.

After a high spike it network load (when we backup all data in the middle of
the night) one
of the ip address will stop responding.  I log in locally and the network
tables are fine, but
when I try to ping out of that network card it gives the error message
"ping: no buffers avaiable"

Taking the nic up then back down (`ifconfig fxp0 down; ifconfig fxp0 up`)
will fix the issuse, but
is a huge problem because it is very distrubating to network operation,
espically during nightly
backups/data merges when no one is onsite.  I replaced the nic with a brand
new one that is the same
model, and also with a new one that is a differant brand/model and it is
still having issuses.

In sysctl I changed (IIRC) "net.inet.tcp.sendspace" and "net.inet.recvspace"
both to 8192 (thinking it is Kb?),
that still had issuses, so I change it to 8192000 (thinking it might be
bytes) and also tried 8192000000.
All these settings still cause FreeBSD to drop the nic.  What is the size of
these variables? (ie. mb, kb, etc ?)

Also, are these the correct settings?  Is network buffers configured some
where else?  I have yet to find
complete and full documentation on sysctl, anyone know where I could get
these docs, freebsd.com has very
incomplete and out of data documentation in regards to sysctl variables and
kernel tweaking in general...

Also is there any type of intelligent networking buffering in FreeBSD?
Something that would
say "If network buffers are full, pause network traffic, flush buffers,
continue with network
traffic" ?  This way, if the buffers are full, it won't take out the nic
completly,
but rather hang it, and then continue after the buffers had be purged?  I
think this would be a more
graceful method of handling this, instead of "Opps, buffers are full, sorry
but your server is useless now"...
Anyone know how to enable this?

Also it is very strange that something this critical isn't logged to syslog,
what do I have to have in
/etc/syslog.conf to get this info, I basically turned on everything to
debug, and didn't see anything to
messages, console or all.log.

It is kinda funny, this server went down again when I was typing this
email.. I can tell when it goes down
cause, winamp disconnects from server and then I hear the solaris admin 4
rooms down swearing at freebsd :)

I got to get this fixed soon or will be forced to move it back to W2K, any
ideas?

Regards,
Jack


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