The OTN transport and switching market

Source: Infonetics Research

The OTN transport and switching market is forecast to grow at a 17% compound annual growth rate (CAGR) from 2011 to 2016, outpacing the 5.5% CAGR of the optical equipment market (WDM, SONET/SDH). So claims a recent study on the OTN equipment marketplace by Infonetics Research.

A Q&A with report author, Andrew Schmitt, principal analyst for optical at Infonetics.

How should OTN (Optical Transport Network) be viewed? As an intermediate technology bridging the legacy SONET/SDH and the packet world? Or is OTN performing another, more fundamental networking role?

There is a deep misconception that once the voyage to an all-packet nirvana is complete, there is no need for SONET/SDH or an equivalent technology. This isn’t true. Networks that are 100% packet still need an OSI layer 1 mechanism, and to date this is mostly SDH and increasingly OTN.

OTN should be viewed as the carrier transport protocol for the foreseeable future. For many carriers, OTN will be used not just for carrying a single packet client, but for interleaving multiple clients onto the same wavelength. This is OTN switching, and it is a superset of OTN transport functionality.

Most people talk about the OTN market but they fail to distinguish between whether OTN is used as a point-to-point technology or as a switching technology that allows the creation of an electronic mesh network.

What is OTN doing within operators' networks that accounts for their strong investment in the technology?

OTN is the new physical layer protocol carrying out the OSI [Open Systems Interconnection] layer 1 functions. Carriers are investing in OTN as part of their continuing investments in WDM [wavelength division multiplexing] equipment, most of which supports OTN transport, a maturing market. The new market is that of OTN switching, which resembles the SONET/SDH multiplexing scheme, but with much better features and management.

OTN switching deployments are directly related to large scale deployments of 40G and 100G transport networks as part of what I like to call The Optical Reboot. As these new wavelength speeds are rolled out, often on unused fibre, other technologies are being introduced at the same time – things like OTN switching and new control plane methods.

"People are underestimating how hard it is to build this [OTN] hardware and combine it with control plane software"

Please explain the difference between the main platforms - OTN transport, OTN switching and P-OTS. And will they have the same relative importance by 2016?

OTN switching is a superset of OTN transport, and the differences are shown in a Venn diagram (chart above) from a recent whitepaper I wrote, Integrated OTN Switching Virtualizes Optical Networks. Somewhere between the two is the muxponder application, which is good for low-volume deployments but becomes expensive and tough to manage when used in quantity.

P-OTS (packet-optical transport systems) are boxes that combine both layer 1 (SONET/SDH and/or OTN switching) with layer 2 (Ethernet, MPLS-TP, other circuit-oriented Ethernet (COE) protocols) in the same hardware and management platform.

Cisco was one of the early leaders in this space with some creative brute-force upgrades to the venerable 15454 platform. Since then, many legacy SONET/SDH multi-service provisioning platforms (MSPPs) have seen upgrades to carry Ethernet. Some of the best examples of this platform type are the Fujitsu 9500, Tellabs' 7100, and Alcatel-Lucent's 1850.

You say a big vendor battle is brewing in the P-OTS space: Cisco, Tellabs, and Alcatel-Lucent are the top 3 vendors, but Fujitsu, Ciena, and Huawei are gaining. What factors will determine a vendor's P-OTS success here?

It really depends. In the metro-regional applications of bigger boxes, things like 100G optics and OTN switching will be more important, as the layer 2 functions are handed off to dedicated layer 2/3 machines. As you get closer to the edge, though, OTN switching will have no importance and everything will depend on the layer 2 and layer zero features.

For layer 2, this means supporting a lightweight circuit-oriented Ethernet protocol with awareness of all the various service types that might be in play. For layer zero, it is all about cheap tunable optics (tunable XFP and SFP+), but particularly ROADMs. I think BTI Photonics, Cyan, Transmode, and ADVA Optical Networking are some of the smaller players to watch here. Mobile backhaul, data centre interconnect, and enterprise data services are the big engines of growth here.

Were there any surprises as part of your research for the report?

There just are not that many vendors shipping OTN switching systems today. I think people are underestimating how hard it is to build this hardware and combine it with control plane software. In 2011, only Ciena, Huawei, and ZTE shipped OTN switching for revenue. This year we should see Alcatel-Lucent, Infinera, Nokia Siemens, and maybe a few more.

Is there one OTN trend currently unclear that you'd highlight as worth watching?

Yes: It isn’t clear to what degree carriers want integrated WDM optics in OTN switches. In the past, big SONET/SDH switches like Ciena’s CoreDirector were always shipped with short-reach optics that connected it to standalone WDM systems. I think going forward, OTN switching and the WDM transport functions must be built into the same hardware in order to get the benefits of OTN switching at the best price, and that’s why I wrote the Integrated OTN Switching white paper – to try to communicate why this is important. It is a shift in the way carriers use this equipment, though, and as you know, some carrier habits are hard to break.

Further reading

OTN Processors from the core to the network edge, click here