Frame Relay circuits and Leased-lines are essentially telephone data services that are obtained from a local telephone company (such as Pacific Bell) or an inter-exchange carrier (such as Metropolitan Fiber Systems). This is how your physical site connect to West Coast Online's network, and how our network connects to the national internet service providers, and to the rest of the Internet world.
Customers on tiered usage rates (e.g., Point-to-Point or co-locates) are charged by average bandwidth used. Usage statistics are on a private web page, viewable by WCO staff and the individual customer only. The graphs show daily, weekly and monthly statistics - by sampling every 10 minutes on our router/ethernet port. We charge by the maximum of the average traffic, either inbound or outbound.
A T1 line sends data at a rate of 1.54 Mbps. Most large Internet service providers (ISPs) send data over a T1 line which connects to a T3 line somewhere down the line. T3 lines generally carry information from several T1 lines.
Both of these T1 connections transfer data to the telephone company at a rate of 1.54 Mbps. The difference between the two connections is in how data is routed from there to the Internet network. With a point-to-point T1 connection, the path to the next hub to get to the Internet network is basically fixed, like on a single two-lane highway. A Frame Relay T1 connection routes data to the next hub through a network of connections, like on a network of highways, with several different ways to get to the same place.
Although both (telco) transmission methods have a maximum data transport rate of 1.54 million bits per second (Mbps), point-to-point circuits are usually faster than Frame Relay circuits, especially in very demanding applications. Two reasons Frame Relay can be slower are:
- There is a small amount of overhead in Frame Relay, about 2-3 %.
- Past 384K, Frame Relay performance depends upon the congestion of the telco.
However, Frame Relay is often preferable to point-to-point circuits if the CIR (Committed Information Rate) required is 512K/second or less, as Frame Relay is cheaper to install and cheaper to network than point-to-point circuits. If your application requires 384K CIR or less, Frame Relay may be the best choice for the speed you need.
If you need maximum speed to only one site, point-to-point may be the best solution. If you need help deciding or have more questions, please contact us. One of our hicap sales engineers will be able to find the best solution for your business.
A big issue in overall performance of an Internet connection is how many different hubs or routing points data must travel through before getting to the Internet backbone, MaeWest. The delays in these hubs, switches, and routers can significantly impact performance. Each additional point data must travel through causes measurable data delays between you, the service provider and the Internet.
Another big performance factor is the amount of activity on the Web site you're attaching to. Access tends to be slower when you're connecting to a Web site that is being accessed heavily.
The biggest controllable performance issue of all, however, is the modem connection between you and your service provider. All of the WCO dial-up lines use 28.8 Kbps modems which support v.34, v.FC, and v.42bis data compression for the fastest possible data transfer available.
CSU stands for "Customer Service Unit", and DSU for "Digital Service Unit". Originally they were two boxes; one owned by the customer and the other owned by the phone company. Once the government forced the phone company to let you connect your own equipment directly to their lines, the boxes were merged into one for convenience. Sometimes a CSU/DSU is called simply a "DSU".
A CSU/DSU is basically a modem for leased-lines. It converts reasonably standard computer electrical protocols such as RS-232 or V.35 to the four-wire RJ-11 telephone company protocol. It also provides and generates status reports about the line itself, the state of the DSU, and the state of other equipment on the other end of the leased-line. Most are able to perform tests of the leased-line and remote DSU when commanded to do so.
Like modems, you need one at each end of a leased-line. WCO provides one for our end of your connection; you need to have one for your end. We sell both Adtran and Digital Link DSU's to our customers. Prices range from $375-$925 and we will configure them for no charge.
A router generally does two useful things for you: it handles the I/O load of reading and writing bits to the leased-line, converting them to Ethernet packets for your computers to deal with. It also takes care of deciding which packets need to go over your leased-line and which ones should be sent locally on your Ethernet. Most routers do other useful things, like handle errors, keep statistics via SNMP, provide dial-in maintenance ports, and handle multiple lines (leased, dial-in or copper).
Most interface to your host computer via Ethernet, and will handle IP traffic to and from any number of host computers. Routers are able to handle nearly any network configuration, using static routing (set up in advance by humans). It's usually more convenient to have them run a routing protocol such as RIP, which allows your router to automatically discover the proper routing by communicating with other routers on the leased-lines and Ethernet.
There are synchronous interface cards available for some computers that handle the I/O portion of the router function. Most Unix machines can handle the routing themselves (though it takes CPU time away from other things you might want to do). By going this route, you may be able to defer, or avoid entirely, the need for an expensive router. However, we know of only one Unix flavor that directly supports one of these cards.