[Pc_Support] Re: ABS 8-Port, 5-Port GbE Switch -- VSC7388, VSC7385 (Blog article)

[Bryan J. Smith]

Derek Konigsberg <octo at logicprobe.org> wrote:
> The biggest difference I believe is cable length limitations, where
> fiber always gives you longer length options.

Not really.  1000Base-SX Multi Mode fiber is not quite 3x 1000Base-T
in distance.  You have to go 1000Base-LX Single Mode fiber to get
length.

> The limit on copper gets really short once you go GigE,

Huh?  Unless you mean EMI resistance at the cable, 1000Base-T _is_
rated for 100m runs, just like 100Base-T and 10Base-T.  There are far
greater issues with ASIC overhead and 1500 byte frames.

> On my x86 machines, my GigE fiber NICs are Netgear GA620's.

I several of those to Intel 510 and Bay 450 switch stacks in the late
'90s.  They have 512KiB SRAM buffer, although that was rather small
for the time (1-2MiB SRAM was typical).  No 802.3x support IIRC.

Today I wouldn't put anything but a wire-speed layer-3 switch,
20+Mbps fabric and use Jumbo Frames for anything GbE or that is
possible of supporting it.  Running with old managed layer-2 switches
typically offer little benefit over today's commodity switch ASICs.



-- 
Bryan J. Smith     Professional, Technical Annoyance
b.j.smith at ieee.org      http://thebs413.blogspot.com
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*** Speed doesn't kill, difference in speed does ***