CCNA
Cisco Certified Network Associate certification resources
Ethernet WAN
Ethernet was initially considered not suitable as a WAN access technology because of the maximum cable length supported was only up to a kilometre. However, newer Ethernet standards with fiber optic have made Ethernet an important WAN option. For example, the IEEE 1000BASE-ZX standard supports up to 70 km of distance. Ethernet WAN provides high-bandwidth...
What is ATM?
ATM is the abbreviation of Asynchronous Transfer Mode. It is using time-division multiplexing (TDM) for data communications. It is capable of transferring voice, video, and data through private and public networks. ATM is working on a cell-based architecture in place of frame-based architecture. The size of the Asynchronous Transfer Mode cell is fixed to 53...
What is Frame Relay? Exclusive Introduction
Frame relay is a packet-switching telecommunication service designed for interconnecting enterprise LANs. Being a student of networking, it is important that you know about all the emerging WAN technologies. To stay up-to-date with emerging and developing technologies, you may know the following alternate options available for WAN connectivity. Frame Relay Broadband DSL Broadband cable modem...
ISDN
ISDN stands for Integrated Services Digital Network. It is a circuit-switched technology using the local loop of a PSTN to carry digital signals. It can transmit both data and voice over a digital line. It is a set of communication standards, which can transmit data, voice, and signalling. ISDN connections provide better speeds and higher...
Dialup
Dialup is a WAN connection technique established using a modem and Active PSTN line. The modem dials a number attached to another computer at the destination end and establishes a connection capable of transferring data. The modem and telephone lines work as a data transfer medium. Usually, a dial-up connection is used as a connectivity...
Leased Lines
Leased Lines are dedicated communication channels between two or more nodes. Usually, it is a pre-established WAN connection from the customer premises to the service provider network. The lines are usually leased from a service provider; they are called leased lines. The leased lines work as a dedicated tunnel from one point to another. It...
What is PDH?
PDH is the abbreviation of plesiochronous digital hierarchy. The term plesiochronous derives from two Greek words: ‘plesio’ means ‘near’ and ‘chronos’ means ‘time’. In the plesiochronous digital hierarchy, the clocks are running close but not exactly matched, so signal arrival times may be different when multiplexing, as the transmission rates are directly linked to the...
What is SDH?
SDH is the abbreviation of Synchronous Digital Hierarchy, which refers to multiplexing techniques and technology used in networking and telecommunications. It is the most popular standard being used in the whole world. The SDH proved a high-speed transfer of data and digital signals. Due to synchronization, Synchronous Digital Hierarchy provides a flexible and simple network...
What is SONET?
SONET stands for Synchronous Optical Networking. It is a protocol for transmitting a huge volume of data over long distances using a fiber optic medium. Synchronous Optical Networking was primarily developed in 1984 and then standardized by the American National Standards Institute (ANSI) in 1988. Using synchronous optical networking, multiple digital data streams are transferred...
Circuit Switched vs Packet Switched
WAN devices discussed in the previous article are incomplete because other devices may be needed, depending on the chosen WAN access technology. WAN access technologies are either circuit-switched or packet-switched. Circuit Switched In a circuit-switched network, communications between end devices must be established before they can communicate. A circuit-switched network establishes a dedicated circuit (or...