Wide Area Networks and Multiplexing Techniques

Wide area networks share a few characteristics with local area networks.

WANs can cover large geographic distances, including the entire Earth.

Many of the same technologies and communications protocols found in local area networks are used to create metropolitan area networks.

LANs cover much greater distances than MANs do.

A WAN's infrastructure consists of a collection of nodes and interconnecting telecommunications links.

MANs cannot be used to support high-speed disaster recovery systems and real-time transaction backup systems.

Because there are so many devices in a WAN, and they are spread over large distances, using a LAN-type connection is not feasible.

WANs require specialized technology designed to manage traffic across a wide variety of devices and connection types.

In frequency division multiplexing, the combined signals are always digital.

Time-division multiplexing (TDM) allows only one user at a time to transmit.

WDM supports multiple lambdas.

Both frequency division multiplexing and synchronous time division multiplexing avoid waste of unused transmission space.

Code division multiplexing is based upon a class of modulation techniques known as spread spectrum technology.

The big advantage of frequency division multiplexing over synchronous TDM is the lower noise due to the use of digital signals during transmission.

Synchronous time-division multiplexing does not require as high-speed a line as statistical time-division multiplexing does.

CDM technology falls into two categories: frequency hopping and direct sequence.

The Lempel-Ziv algorithm can be fairly effective in compressing data.

The basic way to perform compression is to look for some common pattern in the data and replace each data pattern with a symbol or symbols that will consume less space during transmission or storage.

The JPEG encoder produces a data stream that has a much faster data rate than that of conventional CD-quality music.

A video device displays multiple (typically 30) frames per second.

Most wide area networks use some form of Dijkstra's algorithm to determine a least-cost route through a network.

Bellman-Ford algorithm, the Floyd-Warshall algorithm, and Johnson's algorithm are alternatives to Dijkstra's least-cost routing algorithm.

One advantage of dynamic routing is that it never adds to network congestion.

Using a distance-vector protocol, a router monitors each link and the number of hops from that link to network destinations.

A network administrator assigns each routing protocol an AD (administrative distance); the higher the values are, the higher will be the priority.

The first routing algorithm used within the Internet was called a distance vector routing algorithm.

Routing Information Protocol is a link-state protocol.

Cisco's EIGRP is a hybrid routing protocol.

RIP delivers a very small convergence time.

Like RIP, OSPF has hop limits, but it calculates more efficiently the best paths than RIP.

IS-IS (Intermediate System to Intermediate System) is a distance-vector protocol.

A ____ area network is typically confined to a single building or a couple floors within one building.

A network that expands beyond a metropolitan area is a ____ area network.

____ area networks can cover large geographic distances, including the entire Earth.

MANs are almost exclusively ____ networks, and thus capable of supporting data rates into the tens of millions and hundreds of millions of bits per second.

____ is the assignment of nonoverlapping frequency ranges to each "user” of a medium.

____ is the only routing protocol used across the open Internet and can span multiple autonomous systems.

____ is the underlying technology behind applications such as GIF, PKZIP, WinZip, gzip, UNIX's compress utility, and Microsoft's compressed folders.

A network that expands into a metropolitan area and exhibits high data rates, high reliability, and low data loss is called a(n) ____.

The technique of transmitting multiple signals over a single medium is ____.

A(n) ____ is an assigned set of frequencies that is used to transmit the user's signal.

In general, the device that accepts input from one or more users and transmits all these signals through a medium is called the ____.

Unlike OSPF, IS-IS can adapt to IPv6.

The ____ protocol has a limit of 15 hops between routers.

Within OSPF, the ____ link connects exactly two routers.

Path-vector routing protocol communicates via ____-specific messages.

Cable television is still one of the more commonly found applications of ____ multiplex technique.

In the context of multiplexing, ____ is sometimes used to send the same signal across multiple antennas.

When used by 3G phone networks, the code division multiplexing is called ____.

When routing tables adapt to network changes, the routing system is called ____.

With ____ routing, routing tables are created once, typically when the network is installed, and then never updated again.

When something on the network changes, such as a failure or a configuration change, routers must identify the change and adjust their routes, the time it takes for this to happen is called ____ time.

RIP has a 15 hops limit, and for its newer version (RIPv2), the hops limit is ____.

RIP has a ____ hops limit, unlike OSPF.

____ replaces any repetitions of the same bit or byte that occur in a sequence of data with a single occurrence of the bit/byte and a run count, or simply with a run count.

A technique that can be used to compress data when a ____ compression is necessary is the Lempel-Ziv technique.

____ is a common form of audio compression.

____ is a technique that is very commonly used to compress video images.

MPEG-1 and MPEG-2—or simply MPEG—are common examples of ____ compression.

A classic algorithm that calculates a least-cost path through a network is ____ algorithm.