Introduction to WAN Technologies
This chapter introduces the various protocols and technologies used in wide- area network (WAN)
environments. Topics summarized here include point-to-point links, circuit switching, packet
switching, virtual circuits, dialup services, and WAN devices.
What is a WAN?
A WAN is a data communications network that covers a relatively broad geographic area and often
uses transmission facilities provided by common carriers, such as telephone companies. WAN
technologies function at the lower three layers of the OSI reference model: the physical layer, the
data link layer, and the network layer.
Point-to-Point Links
A point-to-point link provides a single, preestablished WAN communications path from the
customer premises through a carrier network, such as a telephone company, to a remote network.
Circuit Switching
Circuit switching is a WAN switching method in which a dedicated physical circuit is established,
maintained, and terminated through a carrier network for each communication session.
Packet Switching
Packet switching is aWAN switchingmethod in which network devices share a single point-to-point
link to transport packets from a source to a destination across a carrier network.
WAN Virtual Circuits
A virtual circuit is a logical circuit created to ensure reliable communication between two network
devices.
WAN Dialup Services
Dialup services offer cost-effective methods for connectivity across WANs. Two popular dialup
implementations are dial-on-demand routing (DDR) and dial backup.
WAN Devices
WAN Switch.
Access Server.
Modem.
CSU/DSU
ISDN Terminal Adapter
More in the PDF file.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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