When is optical networking going to get some respect? That’s certainly a question that optical vendors are asking, and if you think about it, logic would suggest that the area that produces bits should be a major focus when everyone says traffic is exploding. Answering the “When?” question may require understanding why optics isn’t respect-worthy already.
Optical networking evolved from the old days of time-division multiplexing. SONET (in the US) and SDH (Europe and elsewhere) were both evolutions of the older T-carrier/E-carrier electrical transport standards. The focus of networking in those days was to carry 56kbps voice trunks and some leased-line traffic that included data.
When packet networks came along (early ‘80s) the TDM network was pressed into service to provide packet trunks between routers or switches. The more packet we had, the more transport we needed, and everyone loved the growth curve. But under the covers there was a hidden process evolving. Network services, once integrated with transport and optics, were separating.
Everything you do that leaves your neighborhood is probably carried on optical trunks, but you may not “see” an optical interface directly and the service you purchase is probably IP or Ethernet, not an optical service. Nothing focuses your attention like paying for it, and what you pay for are Layer 2/3 services on the old OSI chart, not Layer 1 where optics lives. Out of sight, out of mind.
The real problem started when electrical-layer traffic demand grew to the point where you needed faster packet trunks. When Ethernet at 10Mbps was considered obscenely fast, even a modest optical trunk had much more capacity. There was also still a lot of old TDM hanging around, and so having optical multiplexing as a means of combining slower packet and legacy feeds was valuable. As Ethernet standards evolved, and as optical interfaces directly to switches and routers evolved, and as TDM died off, we suddenly found ourselves in a world where optical trunks were just connectors for electrical-layer devices.
If all traffic is packet, and if the packet device can terminate an optical trunk, where is the “optical network”? There isn’t one. A wire doesn’t make a grid, so a string of glass doesn’t make a network. Optical networks have been devalued by the evolution of electrical-layer services, and if nothing else happens that devaluation is likely to proceed, perhaps even accelerate. The question of optical respect, then, will be answered by answering the question “What might happen?”
The most obvious thing that could happen is an increase in optical capacity that outstrips what a single electrical-layer aggregation device can utilize. DWDM, for example, generates enormous potential capacity, more than most operators would want to stuff into a single box at L2/L3 even if one could carry all of it. If the capacity of an optical fiber is very high, then there’s an incentive to utilize it fully to gain economies of scale and return on the deployment cost.
The problem with this seemingly wonderful and compelling driver is that we’ve had it for over a decade and it hasn’t made optics the center of the universe. What other arrows could a respect-seeking optical layer have in the quiver?
How about the tried and true idea of robbing Peter and keeping the money? To put it more gently, suppose that the optical layer could directly reduce costs at the electrical layer, meaning syphon off feature value from L2 and L3? This is where “agile optics” comes in.
There are a lot of features in routers that could be displaced if you could add them below. Resiliency at the optical level means you don’t see route failures at the electrical level. A number of big Tier Ones have issued RFPs from time to time to explore the creation of what’s effectively an IP “deep core” based on agile optics, and some vendors have products aimed at this very thing.
The problem here is that there aren’t that many core networks. Google has said back in 2010 that if it were an ISP it would be the third-largest and fastest-growing in the world, and Google (as I’ll get to) was really using a different approach than agile optics, and using it at the 10GE level. That doesn’t say a lot for the notion of fast optical networks as essential.
Just as Google might be dashing optical hopes, it could be raising some other hopeful areas. One interesting point is that Google’s Internet-facing network is growing faster than the Internet. Part of the reason for that is that most of the traffic today is the Internet, most of Internet traffic is video, and most video is delivered over a content-delivery network (CDN) and never really gets to the “core” at all. The other interesting point is the cloud. Google’s cloud network (B4) is growing faster than its Internet-facing network (B2), and B4 is their inter-data-center network. How these combine is really interesting.
Optical guys love the data center interconnect application (DCI) but they have a pretty pedestrian vision for it. “Hey, if every enterprise had a hundred data centers and there are ten thousand enterprises globally, that’s a million data centers. Mesh them and look what you get! We’re rich!” Of course 1) every enterprise doesn’t have 100 data centers, 2) you only connect your own data centers, not everyone’s, and 3) you don’t have to mesh them to connect them.
The real growth opportunity for DCI would come not from enterprises but from what’s driving Google’s B4, it’s the internals of a cloud network. Carrier cloud, if it were driven by a combination of CDN, NFV, and IoT, could produce over 100,000 new data centers globally, and these would have to be connected both to each other and to the service edge points.
The key point here is that fiber services could be multiplied if we were to consider the “user” to be an interior logical service element and not an end-user at all. But another lesson of B4 is that Google has built an agile core using SDN trunking and optics, that spoofs IP at the edge to look like a BGP core.
All of this could be done by optical vendors, even with simple agile optics with a veneer of IP-ness to adapt the core to an IP mission. Add in SDN grooming and virtual wires (as B4 does) and you have a product that would look like the heart of an IP network and could serve a bunch of B4-like missions.
Where? Metro. The big optical opportunity is metro, simply because there are a lot of metros compared to cores. In the US there are over 250 “standard” metro areas, and almost 700 that would qualify as distinct metro-network opportunities. Globally there are 2700 suitable metro areas, which is a heck of a lot more than core networks. Not only that, there’s a totally accepted and committed driver for metro spending already in place, waiting to be exploited.
What? It’s 5G. As always we’ve gotten wrapped around the axel with 5G drivers. Operators are committed to 5G for the same reason that somebody gets committed to a weapons program—it takes only one to start an arms race. The trick for operators will be to make something good emerge from the inevitable investment. 5G will offer vendors a chance to demonstrate that can be done, and it will do so in an area where large budgets are already being developed.
There will be a lot of fiber in 5G rollouts, and that massive commitment will both empower optics and stake out a position. If the vendors can’t think of anything insightful they can propose, then they’ll have cemented themselves into a plumbing role, probably for all time, and the electrical layer and SDN players will make optics synonymous with “sand”.