Frame Relay – Frame relay is a secure, private network that utilizes a logical path or “virtual circuit” to allocate bandwidth for high performance transmissions. Frame relay is the premier high-speed packet-switching protocol communicating data, imaging, and voice between multiple locations. Frame relay is available in a range of bandwidths from 56 Kbps to full T1 (1.54 Mbps).
T-1/T-3 – A T-1 is a dedicated phone connection supporting data rates of 1.544Mbps. A T-1 line actually consists of 24 individual channels, each of which supports 64Kbits per second. Each 64Kbit/second channel can be configured to carry voice or data traffic. Most telephone companies allow you to buy just some of these individual channels, known as fractional T-1 access. T-1 lines are a popular leased line option for businesses connecting to the Internet and for Internet Service Providers (ISPs) connecting to the Internet backbone. The Internet backbone itself consists of faster T-3 connections. T-1 comes in either copper or fiber optics.
ATM – ATM stands for Asynchronous Transfer Mode and is a high-speed, packet-switching technique that uses short fixed length packets called cells. ATM can transmit voice, video, and data over a variable-speed LAN and WAN connections at speeds ranging from 1.544Mbps to as high as 622Mbps. ATM is capable of supporting a wide range of traffic types such as voice, video, image and data.
SONET – SONET and SDH are a set of related standards for synchronous data transmission over fiber optic networks. SONET is short for Synchronous Optical NETwork and SDH is an acronym for Synchronous Digital Hierarchy. SONET is the United States version of the standard and SDH is the international version. SONET defines a base rate of 51.84 Mbps and a set of multiples of the base rate known as “Optical Carrier levels.” (OCx). Speeds approaching 40 gigabits per second are possible.
ISDN – Integrated Services Digital Network (ISDN) is comprised of digital telephony and data-transport services offered by regional telephone carriers. ISDN involves the digitalization of the telephone network, which permits voice, data, text, graphics, music, video, and other source materials to be transmitted over existing telephone wires. There are 2 types of ISDN channels:
- B (bearer) – Transfers data at 64Kbps. An ISDN usually contains 2 B channels for a total of 128kbps.
- D (data) – Handles signalling at either 16Kbps or 64Kbps(sometimes limited to 56Kbps) which enables the B channel to strictly pass data
|POTS||Up to 56 Kbps||Twisted pair|
|T-1||1.544 Mbps||Twisted-pair, coaxial, or optical fiber|
|ADSL||256Kbps to 24Mbps (ADSL 2+)||Twisted-pair|
|Cable modem||512 Kbps to 52 Mbps||Coaxial|
|Satellite||1gbps (avg 1-5mbps)||Air|
|T-3||44.736 Mbps||Twisted-pair, coaxial, or optical fiber|
|OC-1||51.84 Mbps||Optical fiber|
|OC-3||155.52 Mbps||Optical fiber|
Packet and Circuit Switching – Packet switching refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message. Most modern Wide Area Network (WAN) protocols, including TCP/IP and Frame Relay are based on packet-switching technologies. In contrast, normal telephone service is based on a circuit-switching technology, in which a dedicated line is allocated for transmission between two parties. Circuit-switching is ideal when data must be transmitted quickly and must arrive in the same order in which it is sent. This is the case with most real-time data, such as live audio and video. Packet switching is more efficient and robust for data that can withstand some delays in transmission, such as e-mail messages and Web pages.
**Source by wikipedia**
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