OTN has taken 100G to the next level

Optical transport networking (OTN) technologies, working in tandem with high-speed transmission gear, have made 100G transport a far more versatile and practical solution than its origins had indicated, and its commercial takeoff is already underway.
Editor: Linda Xu xushenglan@huawei.com
OTN: A technological engine
Optical 100G transport sounds impressive, but it was once a costly underachiever. Access rates for this technology are usually 10G/10GE, with 100G normally achieved in transit as 10G streams are aggregated. However, the real problem with 100G WDM is its inflexibility, which makes itself felt in three different areas.
Firstly, access is inflexible. You cannot simply “cup your hand into the river and start drinking.” Streams and branches cannot be shared or changed without great effort, and the adding of branches requires careful wavelength design on the line side, or the procurement of additional gear.
Secondly, i n t e r m e d i a t e node scheduling is also inflexible, as these nodes are fixed after service deployment. If adjustment is required, the tail fibers for these nodes have to be changed manually, with additional hardware possibly needed; both require time and money.
And finally, 100G pipe utilization is inflexible, as transmission is point-topoint (P2P), with the direction fixed, so idle bandwidth cannot be called upon to supplement more stressed parts of the network – a tremendous waste.
In the era of cloud computing, streaming media, and network overload, traditional P2P transmission just doesn’t cut it. OTN technology is here to help. Its essence is the decoupling of pipes from services, and lines from branches, to realize service flexibility and resource sharing. In short, OTN changes the game.
Optimized network cost
OTN technology integrates optical and electronic technologies into something completely different from traditional P2P wavelength-division architecture. In times past, operators were preoccupied with cost reductions for each & every network element (NE); they now tend to concentrate on optimizing costs for the entire network.
OTN accomplishes this through a tremendous simplification of WDM service logic, enabling flexible allocation and greater management of pipe resources, including multi-service access and switching.
Compared with traditional WDM devices, OTN devices only require electric cross units (ECUs) and a backplane bus; taken together, their cost exceeds that for traditional 100G line cards and optical-layer modules by a modest two percent. Pair that with over-30% improvements in bandwidth utilization and service delivery efficiency, and you have spent a little to save a lot in terms of resource deployment and O&M.
100G is getting bigger
In recent years, OTN technologies have won universal recognition in the industry. In 2013, both Ovum and Infonetics believed OTN technology to be vital to 100G rollout, with the latter pointing out in May that by 2013, 44% of global carriers employed OTN technologies for WDM deployment, with this number expected to hit 89% by 2016.
Infonetics also emphasized that the OTN switching and WDM transport markets are in the process of merging, resulting in an even larger potential market for OTN switching than originally anticipated.
During the 10G era, WDM networks were P2P networks that aggregated services from the synchronous digital hierarchy (SDH) and router system with the WDM technologies for long-distance service transmission. Now, with 10G and 40G, OTN technologies are used in the WDM system, expanding functionality to facilitate switching of certain services. In the 100G era, OTN technologies will mature to closely integrate with 100G network technologies, making for refined management.
Swisscom is always at the forefront of network innovation. Since 2008, the operator has been deploying OTN platforms across its entire network, with said platforms deployed in the core and aggregation layers, as well as the access edge, making for greatly improved bandwidth capacity, availability, and flexibility, as the latter can be adjusted through simple network configuration. This network deployment is a one-off investment, but it can sustain Swisscom’s broadband development for the next ten years.
As the largest 100G network builder in the world, China Mobile is also employing OTN in its 100G deployment. By integrating 100G WDM transport with OTN switching capability, the operator can guarantee both transmission speed and service flexibility. The super-large capacity OTN switching matrix enables the configuration, switching, and protection of services. In the future, China Mobile will gradually implement automatically switched optical network (ASON) technologies on its 100G OTN infrastructure, enabling further sharing of network resources and improved network bearing efficiency & reliability.