[nycbug-talk] Noob networking question

Pete Wright pete at nomadlogic.org
Fri Jul 21 11:38:08 EDT 2006

On Fri, Jul 21, 2006 at 07:40:04AM -0400, Marco Scoffier wrote:
> On Thu, Jul 20, 2006 at 05:03:29PM -0700, Peter Wright wrote:
> <snip>
> Thanks for the network performance analysis tools Pete.
> >> Question 2) I have a few machines off a switch (linksys 100 baseT) which
> >> is connected through the uplink port and a crossover to the main
> >> router/firewall/gateway netgear.  Machines connected to this switch
> >> (which is new) seem much much slower than the rest.  Is there anything
> >> I can do about this ?
> >>
> >
> >have you checked link state (AutoNeg is bad) and that you are full duplex.
> > i dunno, i usually find the basic stuff is a good starting point (check
> >physical links first etc..).
> >
> Super noob question #3. (let me know if this is getting off topic)
> How do I turn off auto negotiation?  The main router and switch in
> question  are both new-ish (like a year old) off the shelf consumer
> networking equipment, (netgear and linksys).  All the client machines
> are Macs running OS 10.4.  Server is FreeBSD with single networking card
> which is aliased to two IPs, one for the base system which is only
> accessible from the inside, a jail hosts some some services available to
> the outside world through port forwarding on the netgear router.  

on *BSD check man8 ifconfig (then look for mediaopt).  This will have
you check the man page for your nic...so on an em card you could force
these settings using mediaopt "1000baseTX  full-duplex" which would
force the NIC to be set to gig-e in full-duplex mode.  These settings
can be specified in /etc/rc.conf.

> All the link state lights seem pinned to a bright green 100x.
> Does that mean that auto negociation is not a problem?  Or is there
> something else I should be checking?
ifconfig should tell you the status of the NIC's for example:

        inet6 fe80::206:5bff:fef6:d294%bge0 prefixlen 64 scopeid 0x1
        inet xxx.xxx.xxx.xxx netmask 0xffffffe0 broadcast xxx.xxx.xxx.xxx
        ether 00:00:00:00:00:00
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active

so on the media line we see that I'm actually using autoselect to bring
up the interface in 100baseTX full-duplex mode.  bad form...i should fix
that ;)

you can obviously use ifconfig to figure out your link status on the OSX
hosts, although I don't remember off the top of my head how force link



Peter Wright
pete at nomadlogic.org

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