Flexible OTN / fractional 100GbE
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.
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