Flexible OTN / fractional 100GbE

Radu-Adrian Feurdean nanog at radu-adrian.feurdean.net
Fri May 31 08:00:32 UTC 2019

On Thu, May 30, 2019, at 09:41, Jérôme Nicolle wrote:
> Yup. Should it hard-drop ? Buffer ? Both are unthinkable in OTN terms 
> (is that a cultural thing ?). It's what packet networks are made for. 
> And that's why an alien device, with support for Ethernet, OTN and 
> programmable pipelines, could bridge the gap, allowing for a more 
> efficient use of optical bandwidth.

Hi Jerome,

When you buy the kind of services that end-up being delivered on OTN, you expect to have a capacity that is dedicated to you, and only to you, and if you don't "use" it nobody else will. And you agree with the constraints that come with that (not protected, or protection is an extra paid option).

Than comes the fact that Ethernet is *NEVER* "fractional". It is either 0 (ZERO) or line-rate. It's the amount (in time) of ZERO present over several microseconds (often "several" == "several millions") that gives (by doing an average) the "sub-rate" bandwidth. So no, hard-drop or buffer on OTN are not only "cultural issues", their absence is technically part of the OTN promise.

If you are willing to accept to share unused bandwidth, then MPLS based services are the way to go, and you have that choice in a vast majority of the cases. You loose the hard guarantee of bandwidth availability and you usually get some trace of jitter.

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