Similarly, the carrier that employed me when 40G debuted did in fact offer 40G, but did its best to steer customers clear of it. By the time 40G client optics were available to us from our optical vendors, those same vendors were already making it clear that we were going to see a lot more efficiency, both spectrally and economically, with 100G. We took that to mean that 40G was going to be a stop gap and not much more than that. So for those ~9 months from when 40G was made available to us until 100G was ready for market, we were happy to sell 40G to anyone who asked; after that, not so much (but we would, and did, until the demand essentially completely disappeared). I imagine most/all of the large carriers were getting the same messaging. By the time the L2/3 vendors were market ready with 40G and 100G shortly thereafter, the die had already been cast, even if none of those vendors saw 40G the same way the optical vendors did.

On Mon, Aug 28, 2023 at 10:52 AM Tom Beecher <beecher@beecher.cc> wrote:
I would agree with that. We've had gear with 40-gig ports for many years (>6)? Never found a CDN or transport network that would do 40.

Many 40G hardware options never made a ton of economic sense in CDN land with shared ASIC lanes for 40G and 100G ports. Using anything 40G blocked the associated 100G port, which were more valuable overall. You also didn't want to create a massive shuffle later, so it made much more sense to just use the 100Gs. You gained flexibility in initial deployment at the cost of inflexibility down the road. 

Newer stuff that has a dedicated 100G per port, but can run at either speed, might actually help 40G deployment since it's just an optic swap. But 100G optic costs have come down enough I think most people are just going to go there.



On Mon, Aug 28, 2023 at 8:20 AM Mike Hammett <nanog@ics-il.net> wrote:
I would agree with that. We've had gear with 40-gig ports for many years (>6)? Never found a CDN or transport network that would do 40.

From: "Mark Tinka" <mark@tinka.africa>
To: "Mike Hammett" <nanog@ics-il.net>
Cc: nanog@nanog.org
Sent: Sunday, August 27, 2023 10:33:07 PM
Subject: Re: MX204 Virtual Chassis Setup



On 8/28/23 03:05, Mike Hammett wrote:
Well, or they simply found a potential deal on hardware that came with 40 gig ports. 40 gigs is still a lot of bits to a lot of people.

For internal use, sure.

But when connecting to another AS, the chances of them supporting 40Gbps in one or more places is inconsistent to slim.

Exchange points may be an exception.

Mark.



--
- Dave Cohen
craetdave@gmail.com