600 Mbps Ethernet vs OC12 SONET

Organizations requiring fractional Gbps bandwidth have traditionally turned to OC12 SONET fiber optic service. It’s still an excellent high speed option, but you should also take a look at 600 Mbps Ethernet service. You may be surprised how the two competing connections compare.

OC-12 (622 Mbps) is the next step up from OC-3 (155 Mbps) in the SONET optical carrier hierarchy. You’ll find this service readily available in Metropolitan Area Networks (MAN) and as a dedicated Internet access connection for mid-size Internet service providers. Large organizations also have OC12 bandwidth connections, especially those with thousands of employees on-site or a need to support high bandwidth applications like medical image transmission or video production and distribution.

Not too many years ago, OC12 was considered a good choice for a carrier fiber optic core network. Now, most regional and national carriers have moved up to OC-48 at 2.5 Gbps or OC-192 at 10 Gbps. Long haul and undersea fiber lines are running at OC-768 (40 Gbps) and moving quickly to support 100 Gbps.

OC12 is most often deployed on a protected SONET ring topology, with two counter-rotating fiber rings. If something in one ring fails, either equipment or a cable break, the other ring will pick up 100% of the traffic within 50 mSec.

Note that an OC12 service is probably not the only traffic on a particular fiber strand. At 622 Mbps, OC12 comes nowhere near using available bandwidth of the fiber. SONET is designed as a Time Division Multiplexed (TDM) system that can easily add or drop common OC service levels such as OC3 and OC12. In addition to the electrically multiplexed services on the fiber, each fiber may also be optically multiplexed into a dozen or more wavelengths using Dense Wavelength Division Multiplexing (DWDM) equipment.

Carrier Ethernet over fiber is based on packet switching rather than time division multiplexing. Without the strict synchronized channels of TDM, Ethernet is far more scalable. You can order 600 Mbps Ethernet as a replacement for OC12 SONET. You can also order 500 Mbps if that is all you reasonably need. Even more importantly, you can start increasing bandwidth to 700 Mbps, 800 Mbps, 900 Mbps and 1 Gbps as business requirements dictate.

With SONET, the service provider will install a managed router as Customer Premises Equipment (CPE) that includes an interface module specifically designed for the particular OC service level you have installed. The modules for OC3, OC12, and OC48 will plug into the same port on the router, but they are not interchangeable. You need to match the particular interface to the OC service level. That becomes important when you want to implement a service change. The provider will need to roll a truck to either swap out interface modules or completely replace the CPE router.

With Carrier Ethernet, your service provider will install a managed router that can support a particular port speed. For Ethernet over Copper, this is likely 100 Mbps. For fiber, you are likely looking at 1 Gbps, although you can often get equipment rated to 10 Gbps if you expect to be upgrading to that speed level in the foreseeable future. With a 1 Gbps port, you can order whatever service level you need between, say, 100 Mbps and 1 Gbps, in 100 Mbps or smaller increments. No equipment changes are needed as you change service levels within that range. You simply call your provider and tell them to increase bandwidth and you’ll see it happen within a few days, sometimes within a few hours.

Beyond scalability, Ethernet has a cost advantage over SONET in most situations. Sometimes the cost difference is dramatic, even half the cost, for Ethernet versus SONET of the same bandwidth. The one limitation that you’ll run into is that SONET has been around a lot longer and is more available than Ethernet over Fiber. Even so, competitive carriers have been aggressively building out their IP networks and may have fiber service closer than you think.

Do you require fractional Gigabit bandwidth services? If so, it is worth your while to compare 600 Mbps Ethernet to OC12 SONET for cost and availability. The same advice is true for other service levels from T1 copper bandwidth on up to 10 Gbps and higher.

Metropolitan Area Networks

We’re all familiar with LANs. Those are the local area networks used in nearly every business to interconnect computers, centralized storage, printers, wireless access points, WiFi hotspots, scanners and, increasingly, telephones and video equipment. When we want to connect to the outside world, we might think of a long haul or WAN connection to the Internet or distant business location. But there is another important type of network in-between the LAN and the WAN. That’s the MAN or Metropolitan Area Network.

The Metropolitan Area Network is an important service in its own right. For many companies, the only long-haul connections they may need are a dedicated broadband Internet and long distance telephone services. Most all of their traffic stays local. Not local as on the LAN, but geographically local. That means within the bounds of a city, suburbs and nearby locations.

This is where the term Metropolitan Area Network got its name. It’s a network that spans a given metropolitan area and not much further. You don’t find MAN services out in the countryside. Not that there aren’t important customers beyond the city limits, mind you. It’s just that MAN networks tend to be build upon fiber optic networks and very little fiber exits out in the boonies right now.

As you might suspect, the greatest concentration of MAN services will be found in business districts of major cities. That’s simply because the greatest population density and number of businesses are also found downtown and in the business districts of adjoining suburbs. Fiber optic cable construction and equipment are expensive. Service providers need lots of traffic from lots of customers to justify the expense of building out a MAN.

It’s possible to construct your own private MAN by ordering point to point lines between each of the locations you want to connect, or by establishing a star network with corporate headquarters at the center. Many companies buy MAN services instead because the costs are lower for a given bandwidth level. That makes sense, since the network infrastructure cost can be amortized over a large user base. A properly run MAN will give you the performance and security you require at a savings over creating your own private network.

How do service providers build a MAN? A classic approach is to construct a fiber optic SONET ring around the city, linking all the important office buildings, industrial parks, data centers and carrier hotels. SONET is the Synchronous Optical NETwork standard for legacy switched circuit telecom services. It features two lit fiber strands sending traffic in opposite directions for redundancy. If one fiber fails, the other picks up the load within 50 mSec.

Newer MAN services are build upon Carrier Ethernet or Metro Ethernet. The core network may still be running SONET or it may be an IP core network. Either way, the customer only sees an Ethernet interface. It may be an E-Line point to point connection or an E-LAN multipoint to multipoint connection. MPLS networks implemented as a MAN have the advantage of being able to handle nearly any type of traffic.

Downtown, you may also have the option of using a wireless MAN. These are based on fixed wireless transmissions between a carrier’s tower and radio equipment at each location served. These are short range services and require line of sight between buildings. If it happens to work out for you, wireless has the advantage of fast installation and low construction cost compared to bringing in fiber to locations not already lit.

Does your business need to communicate between two or more locations in town? If so, Metropolitan Area Networks are what you are looking for. Get prices and availability for now.



Note: Photo of New York City courtesy of I, Laslovarga on Wikimedia Commons.