[vcf-midatlantic] SX GBIC fiber cable speed

Ethan O'Toole telmnstr at 757.org
Mon Feb 15 19:38:36 UTC 2021

FS.COM is pretty good.

I used to work at a place that used 10baseFL. It was a big waste of money. 
Every computer that came in had an Intel 100mbps nic, it got yanked and 
replaced with a $400 10 megabit fiber card. But when lightning struck near 
one of the buildings, it blew out like $100K worth of Lucent Definity 
phone boards and every HP cat5 jetdirect board.

Now at the $day_job at my best point it's a quad LAG of 100-gigabit, for 
400 gigabit total. How far things have come. At last job I saw a rack 
half-full roughly sustaining a terabit per second to the internet. 12 x 1u 
servers maybe.

I still have a Sun and Indigio2 FDDI card or two somewhere, and one for 
Indy. At one point in time I had like 5 Indy/Challenge S all on FDDI. Will 
probably bring some of it to the next swap event.

            - Ethan

On Mon, 15 Feb 2021, Jameel Akari via vcf-midatlantic wrote:

> Before somebody says "it's not vintage!" consider that 1Gb Ethernet on fiber 
> was spec'd for FDDI cables, and there were optical transceivers for even 10Mb 
> Ethernet - I brought a set of AUI to 2xST for the Unix Town networking, just 
> because I had them. Also, early 1Gb Ethernet was all 1000base-SX with SC 
> connectors, at least that I saw.  It took a while for copper UTP to be 
> supported.  I have a few Digital and Sun 1Gb NICs that are optical, and so I 
> run them that way.
> Now, at 25m, you /really/ don't need fiber for 1Gb Ethernet.  Properly 
> installed UTP copper should work reliably for years in normal environments. 
> It's surprising and unusual you had some fail.  Exception: crimped RJ45 ends 
> on solid conductor UTP cable is likely to fail over time if there's any 
> movement or vibration.  Punch on some jacks and use premade jumpers.
> You can run 10Gb over Cat6A UTP at this distance as well.  This is harder to 
> terminate by hand, but you could just get premade patch cables (they will be 
> 26-28 AWG stranded, most likely)
> But since you've already got optics and fiber is a lot cheaper than it used 
> to be... why not?
> - You're better off not trying to use the same cabling for 1Gb and 10Gb, but:
> - You *can* do short-range 1000base-SX with OM3, though it's not spec 
> depending on where you look.  It will work.
> - By the book, use OM2 for 1Gb and OM3 for 10Gb, assuming short-range optics 
> like your SX SFPs. (SFP, not GBIC, if you're talking LC connectors)
> - OM2 is usually orange and OM3 is usually aqua-blue.
> - As far as I can tell, you don't need mode conditioning for SX (short-range) 
> optics.  If you needed to use LR 1Gb optics, or use single-mode optics into 
> MMF cabling plant, then you'd use a mode-conditioning cable to clean up the 
> noise.
> - Bend radius is typically 10x the outside diameter of the cable, unless 
> otherwise specified. Here, it's a single strand of a duplex cable.  So if 
> it's about 3mm across, bend radius is 30mm.  (but see below on 
> bend-insensitive cable). When I dress cables I usually eyeball 3-4" diameter 
> loops.  Any smaller just doesn't look or feel right anyway.
> I'm assuming that at only 25m you're buying pre-terminated cables with LC 
> plugs both ends. This means you need large enough holes in things for those 
> plugs to fit through.  Otherwise it's definitely not worth splicing your own 
> at this scale.
> https://www.fs.com/products/74386.html?attribute=226&id=99219 - for $16.72 
> each at 25m, you get new "bend insensitive" cable (7.5mm radius!)
> I love FS.com for all manner of fiber and related cabling:
> https://community.fs.com/blog/advantages-and-disadvantages-of-multimode-fiber.html
> https://community.fs.com/blog/single-mode-cabling-cost-vs-multimode-cabling-cost.html
> These have some rule-of-thumb charts.
> I think that covers it?
> -- 
> Jameel Akari
> On 2021-02-15 12:25, Neil Cherry via vcf-midatlantic wrote:
>>  I've posted this in the CDL list also. I don't know of a polite way to
>>  post once to both and
>>  I'm not sure it's a good idea to try. :-)
>>  It has been a while since I played with fiber (2010) and I'm trying to
>>  figure out if I
>>  should go fiber or copper in my home. Here's what I know from my current
>>  switch:
>>  - SX GBIC
>>  - LC
>>  - duplex
>>  - MMF
>>  I want to buy about 25M of fiber. I think the price is competitive
>>  with copper. I'm also
>>  hoping that the fiber will age better than the copper. I'm seeing a
>>  few old copper drops
>>  fail to lower settings. One went to 10/half (wow, that's bad).
>>  The GBIC & switch I have handle 1G. So I can easily pop in a few
>>  1000baseT, put them
>>  into a LAG and get 4G (4 ports). So I'm covered for a while.
>>  - Can the same piece of fiber handle 1G or 10G? (in case I upgrade in
>>  the future).
>>  - Does anyone know the bend radius of this fiber?
>>  - What color should I expect for SX fiber. ?
>>  - What's a "mode-conditioning patch cord" ?
>>  I'm seeing a $35 price for 25 Meter OM3 LC LC Fiber Patch Cable
>>  (Corning 50/125um core/cladding)
>>  and it says 1G but with a "mode-conditioning patch cord" (an attenuator?).
>>  Any pointers?

More information about the vcf-midatlantic mailing list