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Date:      Tue, 23 May 2006 11:36:28 -0700 (PDT)
From:      ANE <>
Subject:   slow pings after enabling ipfw+dummynet?
Message-ID:  <>

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After enabling ipfw+dummynet, ping times, even to,
increase from avg .025ms to 2500ms.  Local pings occasionally drop
packets with "No buffer space available".  I set
kern.ipc.maxsockbuf=8388608 which alleviates the frequency of buffer
errors somewhat, but the huge ping times and pauses/timeouts
accessing the machine via the network (SSH, sending/receiving email)
still occur.

If ipfw is disabled, everything returns to normal.  (very low ms,
quick access via the network)

Any ideas why this is happening?


FreeBSD 4.10 with Intel NIC (fxp0)
manually set full-duplex on both server & router

/usr/src/sys/i386/conf/DNET (kernel config file)
options IPFIREWALL              # allow firewall construction
options IPFIREWALL_VERBOSE      # logging
options DUMMYNET                # traffic shaping
options IPFIREWALL_DEFAULT_TO_ACCEPT    # not using packet filtering
just traffic shaping
options HZ=1000                 # recommended in dummynet man page

# ref:
# ref:

# Flush any old rules laying around
ipfw -f flush
# Allow everything in and out
ipfw add 1000 pipe 1 ip from any to any
# Limit to 512Kbit/s
ipfw pipe 1 config bw 512Kbit/s

Make buffer size 8MB instead of 256K to lessen "no buffer space
available" ping failures:
>sysctl -w kern.ipc.maxsockbuf=8388608

Do I have something configured wrong in /etc/rc.dummynet?

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