Date: Mon, 2 May 2005 12:46:33 -0700 From: John-Mark Gurney <gurney_j@resnet.uoregon.edu> To: mc <mc@netx.com.hk> Cc: freebsd-net@freebsd.org Subject: Re: gigabit ethernet (copper/fibre) Message-ID: <20050502194633.GW2670@funkthat.com> In-Reply-To: <005b01c54f2c$a37f6e40$df63af0a@mcpm> References: <005b01c54f2c$a37f6e40$df63af0a@mcpm>
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mc wrote this message on Mon, May 02, 2005 at 23:35 +0800:
> I would like to ask if anyone on the list could point me to some comparison
> charts between optical fibre and copper gigabit ethernet connection?
Right now copper is dirt cheap compared to fibre... Though you can
pick up closely priced stuff off ebay...
you can pay $25-$70 for copper gige, though you get what you pay
for... most $25 cards are realtek based, and can't do unaligned dma
transfers, and so will be more cpu intensive to use on sparc64 and
other processers that doesn't support unaligned memory access...
> recently I am seriously considering to upgrade some of my machines and
> switches to gigabit speeds. seeing that the copper version is so much
> cheaper than fibre (and easier maintenance too), I'd of course want to
> deploy the copper version if possible, but I have no idea what is making the
> big difference (besides the distance of the cable run?).
The other thing is modern gige runs fine over your existing cat5 cables..
Just make sure you aren't splitting it in two, as gige needs all four
pairs of wire to do gige... When I upgraded to gige, I didn't have to
replace any wiring from my 100bt setup...
> besides..could anyone suggest me with some gigabit nic and switches? (would
> be great if you could tell me roughly the price! :)
If you go copper, and don't want need a managed switch, go with SMC's
SMC8505T or SMC8508T, as both support jumbo frames.. and only cost
$100... Most other switch vendors don't support jumbo frames...
> off topic: some time ago, I have tried using intel em(4) nics (tried both
> onboard and desktop version) with a cisco 2950T. the speed was terrible -
> even much worse than a $cheap fxp. is this because intel+cisco =
> incompatible? or is this because copper cannot achieve good performance?
> (sorry for having no meaningful stats to support my question...the test was
> done some years ago and at that time I was too busy to follow up the
> situation)
I'm not sure, but I do know that em has better jumbo frame support
than realtek based cards, and better checksum offloading support (it
works :) )...
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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