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Date:      Fri, 21 Feb 2003 12:19:54 -0500
From:      Bill Moran <wmoran@potentialtech.com>
To:        Joseph Noonan <jfn@msc.com>
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: Bizarre Networking Problem
Message-ID:  <3E565FBA.9020308@potentialtech.com>
References:  <27.39e39215.2b869c70@aol.com> <20030220155544.V84973@pcjfn.msc.com> <3E5570B3.2090201@potentialtech.com> <20030221105259.Y87091@pcjfn.msc.com>

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Joseph Noonan wrote:
> On Thu, 20 Feb 2003 at 7:20pm Bill Moran wrote:
> 
>>Perhaps some output form 'netstat -rn' and 'ifconfig' might
>>provoke some more useful answers.
> 
> Well the problem is solved, but I am not happy about the solution
> as it makes absolutely no sense to me.
> 
> xl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
>         options=3<rxcsum,txcsum>
>         inet 192.246.38.10 netmask 0xffffff00 broadcast 255.255.255.0
>         inet 208.23.240.10 netmask 0xffffff00 broadcast 208.23.240.255
>         ether 00:04:75:b0:24:12
>         media: Ethernet autoselect (100baseTX <full-duplex>)
>         status: active
> 
> The above was the ifconfig when I had the problem.  Notice the
> broadcast addresses.  The commands that brought up the interface
> at boot are:
> 
> /sbin/ifconfig xl0 192.246.38.10 netmask 255.255.255.0
> /sbin/ifconfig xl0 alias 208.23.240.10 netmask 255.255.255.0
> 
> (note that the netmask really is not required as those IP's are
> from traditional class C, but I like to always be specific so I
> don't forget one when I'm working in 'A' or 'B' space.)
> 
> So those commands give two different kinds of broadcast addresses
> and to my way of thinking, the second one (on the 208...) is
> correct.  But if I alias the interface like so:
> 
> ifconfig inet 208.23.240.10 netmask 0xffffff00 broadcast 255.255.255.0

That doesn't look right.  The broadcast address should be 208.23.240.255
for that IP and 192.246.38.255 for the other one.
Can you try these broadcast addys and see if the problem is fixed there
as well?

> The sluggishness on the 208 net goes away.  I don't understand it,
> but it works.  I don't like stuff this, it creeps me out.

Can't argue with you.  I don't see how what you did would fix anything.
However, I'm not surprised that ifconfig doesn't guess the right action
all the time.  I wouldn't get upset if you have to specify the broadcast
addy to be sure it's right.

-- 
Bill Moran
Potential Technologies
http://www.potentialtech.com


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