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Date:      Fri, 21 May 1999 07:38:19 -0600 (MDT)
From:      "Aaron D. Gifford" <agifford@infowest.com>
To:        freebsd-isp@freebsd.org
Subject:   Re: ifconfig_if0_alias?
Message-ID:  <19990521133819.AD2C920F65@infowest.com>

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I think I know why I'm getting about 30ms. improvement
consistently by adding a route for IP aliases on my
FreeBSD-3.2-STABLE box--I am running with IPFIREWALL
enabled in my kernel and one of my first 'ipfw' statements
is 'ipfw add 100 permit all from any to any via lo0' so
loopback traffic never has to traverse as many 'ipfw'
filters.  I'm not positive that this is the ONLY reason
I see the improvement, but it could certainly explain
why others on the list don't seem to see a difference.

Here's another ping test:

#ifconfig in0 inet 10.200.200.150 netmask 0xffffffff alias
#ping -s 1024 -c 1000 -q 10.200.200.150
PING 10.200.200.150 (10.200.200.150): 1024 data bytes

--- 10.200.200.150 ping statistics ---
1000 packets transmitted, 1000 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.118/0.138/2.331/0.071 ms
#route add -host 10.200.200.150 -iface lo0
#ping -s 1024 -c 1000 -q 10.200.200.150
PING 10.200.200.150 (10.200.200.150): 1024 data bytes

--- 10.200.200.150 ping statistics ---
1000 packets transmitted, 1000 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.099/0.115/0.268/0.014 ms
#route delete -host 10.200.200.150
#ifconfig in0 inet 10.200.200.150 netmask 0xffffffff -alias

The results are about the same every time I do it, improving
ping times by about 30-32ms on average by adding the loopback
route for the IP alias.  Again, this may only be because
of quicker ipfw processing due to the way I've structured
my filters.

Aaron out.



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