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Substation Communications
Published in John D. McDonald, Electric Power Substations Engineering, 2017
Frame relay is a service designed for cost-efficient intermittent data transmission between local area networks and between end points in a wide area network. Frame relay puts data in a variable-size unit called a frame and leaves error correction up to the end points. This speeds up overall data transmission. Usually, the network provides a permanent virtual circuit (PVC), allowing the customer to see a continuous, dedicated connection without paying for a full-time leased line. The provider routes each frame to its destination and can charge based on usage. Frame relay makes provision to select a level of service quality, prioritizing some frames. Frame relay is provided on fractional T1 and full T-carrier. It provides a mid-range service between ISDN (128 kbps, Section 15.12.2) and ATM (155.520 or 622.080 Mbps, Section 15.12.6). Based on the older X.25 packet-switching technology, frame relay is being displaced by ATM and native IP-based protocols (see discussion of MPLS).
Networking Basics for A/V
Published in Al Kovalick, Video Systems in an IT Environment, 2013
A WAN is a physical or logical network that provides communication services between individual devices over a geographic area larger than that served by local area networks. Connectivity options range from plain-old telephone service (POTS) to optical networking at 160 Gbps rates (proposed). Terms such as T1, E3, DS0, and OC-192 are often referred to in WAN literature, and frankly this alphabet soup of acronyms is confusing even to experts. There is no need to sweat like a stevedore when parsing these terms. See Appendix F for simple definitions and relationships of these widespread terms. Some of the links discussed in the appendix are used commonly to connect from a user’s site to a Telco’s office. Other links are dedicated to the generic Telco’s internal switching and routing infrastructures. Usually, a WAN is controlled by commercial vendors (Telcos and the like), whereas a LAN is controlled by owners/operators of a facility or campus network. The QoS of the network depends not only on the type, but who controls it.
Computer Technology Primer
Published in Michael M. A. Mirabito, Barbara L. Morgenstern, Mitchell Kapor, The New Communications Technologies, 2004
Michael M. A. Mirabito, Barbara L. Morgenstern, Mitchell Kapor
A LAN, like a multiuser configuration, makes it possible to share system resources. The LAN has an advantage, though. In the typical multiuser environment, the whole system may come to a crashing halt if the central computer “goes down.” In a LAN, each PC has its own processing capability and may be able to operate independently if the network is rendered inoperable by equipment failure. This advantage, when weighed with cost-effective PCs/network components and other factors, have made the LAN the networking tool of choice. A wide area network (WAN) extends these capabilities over greater geographical distances and can tie LANs together through different communications channels.31
A Survey on Packet Switching Networks
Published in IETE Journal of Research, 2022
Different computers are connected through a network. Connecting different computer systems under the same premises is considered a Local Area Network (LAN), while a WAN is the primary network(s) of ISP(s) (Internet Service Provider), which interconnect(s) the LANs. All the networking within an ISP or between different ISPs connected through routers. High-speed networks have become vital due to frequent video conferencing, online teaching, virtual meetings, etc.