Flexible OTN / fractional 100GbE

Brandon Martin lists.nanog at monmotha.net
Wed May 29 18:24:05 UTC 2019


On 5/28/19 11:12 AM, Jérôme Nicolle wrote:
> OTN is important for this project because we'd need many of its features
> in terms of FEC, monitoring and low jitter.

Correct me if I'm wrong, but wouldn't "fractional" Ethernet services 
require packet switching with corresponding jitter anyway?  It would be 
1:1 switching which would keep the latency low, but you can't e.g. offer 
a 60Gbps bandwidth on 100GbE handoff and just put that straight on OTN. 
   You'd have to either packet switch (and queue due to the incoming 
line rate being slower than the outgoing) it onto a FlexODU using GFP-F 
at 60Gbps (I'm not sure if anything even supports this) or just take the 
100GbE staight onto OTN at 100Gbps.

Now, you could obviously put two native 40GbE services onto a single 
OTU-4 (along with a couple 10Gbps or single 20Gbps packet service) 
without packet switching by just framing up both Ethernet services using 
your choice of GFP-F or GFP-T, and it could be done without queuing 
since the incoming and outgoing line rates are the same.

The former would probably still end up being better than straight 
switched Ethernet, but it won't be the same as a straight re-framed 
Ethernet signal on OTN.

FEC and enhanced monitoring are always nice, though.
-- 
Brandon Martin



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