Carrier Services
Carrier Services |
Applications |
Data Bandwidth |
|
Traditional Switched Analog Lines |
Dial-up Lines | Not delay-sensitive traffic: file transfer & e-mail | Modem up to 43Kbps |
| Dedicated Lines (leased) | Permanent connection; Expensive | ||
| Circuit Switched | Switched 56 services | Digital; most often used as a backup to higher speed data services, for fax transmission & file transfer | No modem, use CSU/DSU(channel service unit/data service unit) between Router & digital lines; 56Kbps |
| Integrated Service Digital Network | The first all-digital dial-up service; provide integrated voice & data services | Basic ISDN service: BRI(Basic Rate
Interface) 2 64Kbps(B channel) for data & 1 16Kbps (D channel) for signaling Primary Rate Interface (PRI): 23 B channels & 1D channel |
|
Packet Switched Services |
X.25 | Remote terminal connection; not suitable for LAN-to-LAN because of the time and bandwidth consumed by extensive error checking | Up to 2Mbps |
| Frame Relay | Son of ISDN; faster & more efficient than x.25; an excellent choice for any-to-any connections on an as-needed basis; uses statistical multiplexing | Faster than X.25; $ 120/mo for 56Kbps; $650 for 1.544Mbps with high one-time installation fee | |
| Cell Switched Service: the smallest unit of data switched is a fixed-size "cell"; switching to be accomplished in hardware w/o complex & time-consuming frame-by-frame route calculation | ATM (Asynchronous Transfer Mode): | Integrates LAN functions, wide area functions, voice, video, & data into a single uniform protocol and design; Dedicated bandwidth guarantees an application's consistency of service; Universal deployment( potential for an end-to-end solution, meaning it can be used from desktop to local segment to backbone to WAN; Recommended for video applications, Backbones, WAN & widely dispersed networks because of its lack of distance limitations | 25 - 622 Mbps (potentially in gigabits/second) |
| Switched Multimegabit Data Service (SMDS) | Provided by the Regional Bell Operating Companies (RBOCs); provides usage-based billing & network mgt.; "metropolitan area service" | DS1(1.544 Mbps) & DS3 (45 Mbps); relatively expensive to purchase, install & maintain | |
| Dedicated Digital
Services: Voice, video & data; leased from LEXs between two points (point-to-point) |
T1: "Don't let your data signals leave home without it" |
Most widely used; most reliable & cost-effective; used time division multiplexing; 24 64 Kbps digital channels; can find T1 services practically everywhere | 1.544 Mbps; Probably the lowest cost wide area telecommunications service |
| Fractional T1 | For those who require channels at 64 Kbps, but don't need a full T1.; usage based T1 service; | Up to 1.544 Mbps | |
| T3 | 28 T1 lines or 672 Kbps channels | Up to 45 Mbps | |
General Recommendations |
File Transfer | Batch file transfer: traditional circuiy services(T1 & SMDS) light/intermittent: switched-circuit service constant/lengthy: dedicated-circuit service |
|
| Multimedia/Videoconferencing | ISDN | ||
| Wide Area Workgroup (eg., Lotus Notes) | Traditional circuit services because solid, stable, ralatively inexpensive and easy to install & maintain | ||
| Internat Access | Frame Relay because flexible, inexpensive & easy install & maintain | ||
