As users of MAN and WAN telecom services, we’re acutely aware of the bandwidth we’ve contracted for. What once was seemed like more than adequate line speed now seems a bit confining. In the worst case, applications don’t run right and productivity slows to a crawl as everyone waits on something to download. Now, what’s needed to jack up the bandwidth and get rid of all that congestion?
Every Connection Has its Speed
You can often run any line at less capacity than it is capable of, but not more. Factors that go into the maximum speed include type of transmission medium, such as twisted pair copper, coaxial cable, fiber optic strands, or microwave wireless. They also include the capability of the port on the access router or other customer premises equipment (CPE). Let’s have a look at some common connectivity solutions and their port speeds.
T1 lines run at a synchronous speed of 1.5 Mbps. Synchronization between source and destination is typical of the TDM or Time Division Multiplexing technologies that include T-Carrier (T1, T3) and SONET (OC-3, OC-12, OC-24, OC-48). The way these lines carry traffic is to chop up a fixed line speed into smaller pieces called channels. T1 happens to have 24 channels of 64 Kbps each. That turns out to be just right for packing one telephone conversation into each channel. For data traffic, all the channels are combined into one large pipe.
It’s easy to see how you can have less than 1.5 Mbps by using fewer channels or rate limiting the data speed. This used to be popular as a cost savings mechanism when T1 lines were very expensive. Nowadays, 1.5 Mbps is considered an entry level broadband at best. So, how do you get more than 1.5 Mbps out of a T1 line?
Short answer: You don’t. Longer answer: You combine or bond two or more T1 lines so they act like a single transmission line. This gives you the option of creating bandwidths from 3 to 12 Mbps. The thing to remember is that every time you want to add another line, it has to be physically installed by the same carrier. They will usually have to change out your CPE as well as connecting the additional line wiring.
T3 Lines or DS3
T3 and DS3 are pretty much the same thing, although there is a hair of technical difference between those designations. They both run at 45 Mbps and are delivered on a pair of coaxial cables to a specific plug-in card on your router. What you don’t see is that the DS3 signal almost always runs multiplexed on a SONET fiber optic service to the curb. All of these are TDM services, like T1 lines on steroids.
SONET Fiber Optic
SONET or Synchronous Optical NETwork is a family of standards that offers an easy upgrade from T-carrier. Yes, SONET still uses the 64 Kbps channels when it is set up for telephone trunking. Otherwise it offers a very large data pipe that can also be used as a SIP trunk.
Like T-Carrier, every flavor of SONET has a different interface. You’ll need specific cards or carrier supplied routers for OC-3 at 155 Mbps, OC-12 at 622 Mbps, OC-24 at 1.2 Gbps, OC-48 at 2.4 Gbps and OC-192 at 10 Gbps. You can sometimes get rate limited bandwidth at each level for some cost savings.
Ethernet over Copper
Ethernet over Copper (EoC) uses the same twisted pair transmission wiring at T1, but is capable of higher speeds, albeit at shorter distances. Typical bandwidth range from 3 on up to at least 10 or 20 Mbps. In special circumstances, this can be increased to 50 or 100 Mbps.
Ethernet is a bit different from TCM in that there are no synchronous channels. Instead, everything is carried by packets. The number of packets that the line will carry each second is its bandwidth. The bandwidth you can get depends on the capability of your carrier and the speed of the installed port on the CPE. Most often this is a managed edge router they install in your premises.
You simply plug into the Ethernet port on the router using a standard RJ-45 Ethernet cable. Port speeds follow the Ethernet standards of 10 Mbps and 100 Mbps. If you have the 100 Mbps port installed, you can specify the bandwidth you want in fairly small increments up to the technical capability of the connection. Better yet, you can tell the carrier to change your bandwidth at any time and it will be done quickly. Some carriers even let you make the change yourself through your web browser.
Ethernet over Fiber
Ethernet over Fiber (EoF) works just like Ethernet over Copper except that it runs on fiber optical cabling all the way and offers nearly unlimited speed options. Your access ports can be copper or fiber connections. Twisted pair copper jacks make sense for 10 Mbps, 100 Mbps and 1000 Mbps ports. Fiber connections are used for 10 Gbps and above.
Fiber has become far more economical in just the last few years. Today it makes sense to install Ethernet over Fiber service as low at 10 Mbps. With a typical 1000 Mbps port, you typical have all the expansion capacity you’ll need for the foreseeable future. There won’t be any equipment changes needed until you breach the Gigabit Ethernet bandwidth level. Then it’s likely you’ll move up to a 10 GigE port. By that time, 100 GigE ports may be rule rather than the exception.
TDM services such as T1, T3 and SONET are proven technologies, but they represent the past in telecommunications and networking. The new competitive carrier networks are designed around Ethernet for scalability and compatibility with the Ethernet protocol that runs nearly every company network. In most cases, you’ll find that Ethernet offers a cost savings over TDM in both the copper and fiber formats. That cost savings can be as much as half or more depending on what’s available in your area.
Is your current connectivity starved for bandwidth? Clearly, it’s time to consider an upgrade. Get competitive quotes on copper and fiber optic services available for your location and be sure to specify a port speed that will handle both your current and expected needs.