Flexible OTN / fractional 100GbE

Brandon Martin lists.nanog at monmotha.net
Thu May 30 01:46:28 UTC 2019

On 5/29/19 3:53 PM, Mitcheltree, Harold B wrote:
> https://www.ekinops.com/products/flexrate-modules/aggregation-and-encryption-modules/pm-100g-agg

I'm not sure I see how this particular product resolves the concern I 

Yes, it will aggregate native subrate services at 10Gbps or 40Gbps 
native line rate up onto 100G OTN (on OTU4), and it can (presumably) do 
that without packet switching using either 1:1 frame mapping using GFP-F 
or straight cut-through stream mapping with GFP-T or similar.

What it doesn't appear to do, and where my concern lies with the OP's 
desires surrounding OTN, is take a "fractional" 100Gb service and 
aggregate it up with other services onto an OTU4.  "Fractional" here 
means that the committed/available throughput is something less than the 
native line rate which is what OP appeared to be asking for 
("'fractional 100GbE' e.g. starting with 30-60Gbps commit").

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.

I don't see any reason you can't do this, though I know of no equipment 
that will off hand, and it will incur some latency and jitter due to the 
packet switching which OP seemed to want to avoid.  You'd still get the 
benefits of FEC, enhanced monitoring, etc. from the OTN side of things, 
and the latency and jitter should be generally better than switching it 
onto a higher-rate native Ethernet even if the high-rate side is not 
oversubscribed.  It should certainly be no worse.

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.
Brandon Martin

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