SONET Rings To Support Ethernet

The hot bandwidth service these days is Carrier Ethernet. Everybody wants it once they see the cost advantage over the WAN connection they have now. The big question is can they get it?

In most cases, the answer is yes for a couple of reasons. First, new competitive carriers are rapidly building out their fiber optic core networks based on IP from the start. These networks are tailor made for Carrier Ethernet services. It’s relatively easy to get a point to point Ethernet connection between two distant business locations and use it to link their respective LANs. The result is one larger bridged LAN that enables all employees to be on essentially the same corporate network.

The other reason that Ethernet WAN services are so readily available is that established SONET fiber optic networks are being pressed into service to deliver Ethernet to the customer. This is known as Ethernet over SONET or EoS. The core of the network is still SONET, but operations at that level are invisible to you. As far as you are concerned, your connection is Ethernet all the way.

There’s no reason that SONET can’t transport Ethernet, ATM or other protocols. It was designed as a transport technology and has been adapted over the years to carry whatever traffic required hauling. The origins of SONET, like T-Carrier, are with the telephone industry. The name is an acronym for Synchronous Optical NETwork. Note the term synchronous. That tells you SONET is set up to be a highly synchronized network. The designed is based on multiplexing thousands of small channels called DS0s that each hold one telephone call. These DS0 building blocks can be combined to create T1 and T3 lines or SONET services such as OC-3, OC-12 and OC-48.

The beauty of synchronization for circuit switched architectures based on time division multiplexing is that everything is orchestrated so tightly and you can easily multiplex and demultiplex channels and higher level services. The device that does this is called an ADM or Add/Drop Multiplexer. An ADM can drop off a T1 line, DS3, OC3 or other service at your door from a much higher speed fiber line that carries traffic for many customers.

How does Ethernet squeeze into those tiny telephone channels? It takes some doing, considering that each DS0 carries exactly 64 Kbps. That’s about the speed of an old dial-up modem. What the industry has done is replace the telephone oriented channels with large concatenated frames and various mapping techniques to more efficiently carry Ethernet packets. SONET networks can now readily carry Ethernet services from standard 10 Mbps Ethernet to 100 Mbps Fast Ethernet, 1000 Mbps Gigabit Ethernet (GigE), and 10 Gigabit Ethernet (10GigE).

A feature of most SONET networks that makes them highly reliable is their twin ring design. Two separate fiber strands are used simultaneously. Each carries the same traffic, but in opposite directions. If a fault occurs in the working ring, the network switches over to the protection ring within 50 mSec. This self-healing property works best when the two rings are widely separated so that a single backhoe cut or equipment fault doesn’t take out both rings at once.

Ethernet over SONET and native IP networks are making Carrier Ethernet services of all speeds readily available for businesses looking to upgrade their bandwidth connections at reasonable costs. How much are we talking? Find out with an instant online Ethernet Fiber quote for 10 Mbps to 1 Gbps service levels. Higher bandwidths and SONET services quotes need some manual effort but will be sent to you promptly.