On a related topic and using the same rationale, we are working with industry partners on standardizing a simple and DCI pluggable point-to-point line-system, with the EDFAs integrated into QSFP. This would be optimized for around 100 km and 8-16 channels of 400G-ZR wavelengths, for which most existing solutions are over-capable in the context of IPoDWDM applications. The short target distances also have a strong positive correlation to scenarios in which fiber is plentiful, capacity requirements limited, and thus where spectral efficiency less of a concern. Traditional line-systems for this application come with all the before-mentioned caveats mentioned about discrete transponders in section 2., including surplus components (CPUs, power feeds, fans/cooling), intra-device redundancy, mgmt. interfaces and software, monitoring, and front-heavy deployments from a CAPEX perspective. Because these pluggable EDFAs will be implemented in a QSFP-DD, they will also backward compatible to QSFP28 and as such (as opposed to existing solutions):
- Can be plugged into any QSFP cage, offering an opportunity for uniformity and in some (QSFP28) save on forwarding silicon
- For the few companies deploying OSFP cages, a passive adapter can be used for compatibility
- Reuses most existing standards for control and monitoring
In addition, it provides a much-needed reset of traditional vendor commercial models, fosters ease-of-adoption of 400G-ZR and is very straightforward operationally.
Although embedding EDFAs into pluggable optics for booster and pre-amplification functionality is nothing new, it’s becoming much more relevant when there’s finally a high-volume use-case for IPoDWDM in many SPs access and aggregation domains.
This is especially true when considering the reach of direct-detect technologies becomes ever-shorter as data rates go up beyond 400G. It can potentially also address inter-working with brownfield deployments when 400G-ZR wavelengths launching at -10 dB have to co-exist with traditional ones. Consider Figure 5 and an illustrative subset of <120 km circuits and their respective capacity in Mbps:
Figure 5 – Distance to Capacity relationship in sample metro
In this subset, there is no circuit larger than 1.8 Tbps. If assuming a 16-channel system of 400G-ZR yielding a total of 6.4 Tbps, the spectrum utilization would be just 28%.
The other aspect when taking into account the beforementioned radical cost structure changes is that for these (relatively) low-capacity and short-distance deployments primarily for access and aggregation, a traditional (albeit for simple point-to-point) OLS may now very well represent the most significant part of CAPEX (and OPEX, respectively) for new deployments.
Having a uniform solution to adress scenarios for brownfield inter-working, distances >40 km and/or muxing/demuxing of multiple 400G-ZR then becomes very powerful and presents the very first potential high-volume deployment for (Q)SFP pluggable EDFAs across network operators worldwide. Especially for scenarios within the teal dotted box of Figure 7, which have previously had a relatively high deployment cost.
Conclusions
In this subset, there is no circuit larger than 1.8 Tbps. If assuming a 16-channel system of 400G-ZR yielding a total of 6.4 Tbps, the spectrum utilization would be just 28%.
The other aspect when taking into account the beforementioned radical cost structure changes is that for these (relatively) low-capacity and short-distance deployments primarily for access and aggregation, a traditional (albeit for simple point-to-point) OLS may now very well represent the most significant part of CAPEX (and OPEX, respectively) for new deployments.
Having a uniform solution to adress scenarios for brownfield inter-working, distances >40 km and/or muxing/demuxing of multiple 400G-ZR then becomes very powerful and presents the very first potential high-volume deployment for (Q)SFP pluggable EDFAs across network operators worldwide. Especially for scenarios within the teal dotted box of Figure 7, which have previously had a relatively high deployment cost.
- Minimize time spent in sourcing and validation by automating operations and reducing complexity to onboard new technologies faster as they become available
- Map depreciation times to the (new) economically viable lifetime of equipment
- Reuses most existing standards for control and monitoring
