nanog mailing list archives

Re: Hi-Rise Building Fiber Suggestions


From: Filip Hruska <fhr () fhrnet eu>
Date: Wed, 26 Feb 2020 17:43:40 +0100

It really depends on what you're interconnecting. 

Some NICs don't support SM optics, so even if you would like to run SM everywhere, it's not necessarily possible 
depending on the equipment.
For example, I had issues with some SolarFlare cards which happily take 10G-SR MM but won't take 10G-LR SM.

Filip

On 26 February 2020 5:30:56 pm GMT+01:00, Warren Kumari <warren () kumari net> wrote:
On Wed, Feb 26, 2020 at 11:20 AM Coy Hile <coy.hile () coyhile com> wrote:

On 2020-02-26 11:14, Randy Bush wrote:
We use plenty of multi-mode, but only in the data centre, between
our
own kit, for racks within the same cage.

so you have to stock both single and multi?  hmmm

randy

I'd expect that from the ToR -> Servers would be MMF, but that other
infrastructure cabling would be SMF.
Even using aftermarket optics, putting single-mode transceivers in
every
server and access port would quickly become cost-prohibitive, would
it
not?

Cisco GLC-SX-MM Compatible 1000BASE-SX SFP 850nm 550m DOM Transceiver
Module - $6.00 - https://www.fs.com/products/11774.html
Cisco SFP-GE-L Compatible 1000BASE-LX/LH SFP 1310nm 10km DOM
Transceiver Module - $7.00 - https://www.fs.com/products/12622.html

Yup, it is $1.00 more for SM, and you need 2 per link, but unless you
are doing *lots* that's likely not cost-prohibitive. The delta on 10G
is a bit more ($21 vs $18), but still not crazy-pants territory...

Of course, sometimes you don't have the option of SM - you are
connecting some someone else than they only do MM, or you are
connecting to a piece of kit which doesn't have replaceable optics, or
you have legacy cabling which is MM, or... but, the cost of the optics
these days is not really the limiting factor.


--
Coy Hile
coy.hile () coyhile com



-- 
I don't think the execution is relevant when it was obviously a bad
idea in the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair
of pants.
  ---maf

-- 
Sent from my mobile device. Please excuse my brevity.

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