Flexible OTN / fractional 100GbE

Jérôme Nicolle jerome at ceriz.fr
Thu May 30 07:40:05 UTC 2019


Le 30/05/2019 à 03:46, Brandon Martin a écrit :
> The only way I know to do this is to packet switch, as either Ethernet 
> or GFP-F OTN traffic, the subscriber data onto a FlexODU at the desired 
> subscriber rate within the OTU4.  Other traffic could then be placed 
> within the same OTU4 using the normal OTN TDM mechanisms including 
> subrate (e.g. 10Gbps) traffic that might NOT require packet switching 
> since it could be re-framed/re-transmitted onto the OTU4 at its native 
> line rate.

You're right on spot !

What I have in mind is actually to combine line-rate ODUs with a static 
mapping and pipe the uncommitted capacity to a packet-switch.

Statically commited services will be muxponded in fastpath, hence no 
jitter and less latency, while the fractionnal ports use the remaining 
ports, mostly for low-priority IP traffic.

Now I was assuming ODUFlex in CBR mode would allow fractionnal services 
without packet switching, but mapping an ethernet service to it would 
require some equivalent glue logic I guess, specifically for this case :

> The crux of this is what happens when you have a subscriber service 
> who's native line rate exceeds the provisioned OTN throughput which is a 
> scenario OP alluded exactly to.

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.

Best regards,

Jérôme Nicolle
+33 6 19 31 27 14

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