Chapter 11 Review

What is a WAN Site

Individual geographic location connected by WAN.

What is the drawback of the WAN Bus Topology?

It is NOT scalable.

What single advantage is Partial-mesh for WAN to be known for?

It is known to be less costly.

What is the best USE of Ring Topology of WAN?

It is of well use when it is used to connect a maximum of five locations.

Are there alternatives to reach the same efficiency as T3?

Multiple T1's may accommodate needs to reach the T3 efficiency.

What is the best USE of Bus Topology of WAN?

Organizations requiring small WAN and dedicated circuits.

What is a Data Terminal Equipment(DTE)?

A customer's endpoint device on the WAN and communicates on the LAN.

What is a Frame Relay?

A group of Layer 2 protocols originally designed as a fast packet-switched network over ISDN. It is also a connection-oriented protocol.

What is a Wide Area Network(WAN)?

A network traversing some distance connecting any LANs. The transmission methods depend on business needs.

What is the Local Loop(Last Mile)?

A portion that connects to residence or the business that is nearest to the CO.

What is a Network Interface Unit(NIU)?

A termination point at customer's demarcation point.

What is an Optical Network Unit(ONU).

A unit that distributes signals to multiple endpoints using fiber-optic, copper or coax cables.

What is Fiber To The Premises(FTTP)?

A use of a fiber-optic cable to connect a home or business which is also an example of a digital local loop.

What is Broadband Cable?

Cable company's connectivity option.

What is a WAN Link?

Connection between one WAN site and another site.

What is a Data-Link Connection Identifier(DLCI)?

Identifier routers that read to determine which circuit to use for the frame.

What is the difference between LAN and WAN?

The difference goes as follows: - LANs connect nodes; WANs connect networks. - Layers 1 and 2 access methods, topologies and media. - LAN Wiring: Privately Owned. - Wan Wiring: Public through Network Service Providers(NSPs).

What are the characteristics of Modulation?

- Some create multiple narrow channels in the higher frequency range. A splitter must be installed at the carrier and at the customer's presmises to separate data from voice. - Some require the use of a filter to prevent high-frequency DSL signals from reaching the telephone. - Other types of DSL cannot use the same wire pair used for voice signals. Use the extra pair of wires contained in the telephone cable.

What are the T-carrier standards(T-CXR standards)?

- Specifies a method of signaling. - A physical layer operation.

What characteristics does WAN Topologies have that differ from LAN Topologies?

- The distance they must cover. - The larger number of users they serve. - Heavy traffic they often handle.

What is a Channel Service Unit/Data Service Unit(CSU/DSU)?

- Two separate devices. - Combined into single stand-alone device or an interface card. - T1 line connection point.

What is the Fractional T1 lease?

- Uses some T1 channels to be charged accordingly. - Best suited to businesses that expect traffic to grow but cannot currently justify leasing a full T-1.

What are the characteristics of Capacity and Maximum Line Length?

- Varies in terms of capacity and maximum line length. - VDSL carries as much as 52 Mbps can extend only a maximum of 1000 feet. - Most popular from of DSL is ADSL. The latest version is ADSL2+M. Also provides maximum throughput of 24 Mbps downstream and 3.3 Mbps upstream.

What is a Passive Optical Network(PON)?

A carrier that uses fiber-optic cabling to connect with multiple endpoints.

What is Data Communications Equipment(DCE)?

A carrier's endpoint device for the WAN and only communicates on the WAN.

What is an Optical Line Terminal?

- A Device with multiple optical ports (PON interfaces). - A Single Endpoint at a carrier's central office in a Passive Optical Network(PON).

What is the Center Office(CO)?

- A location where a telephone company terminates lines. - Switches calls between different locations.

What is the Public Switched Telephone Network(PTSN)?

- A network of lines that a carrier uses equipment to provide telephone service. - Also known as Plain Old Telephone Service(POTS). - The network encompasses the entire telephone system. - Originally: Analog traffic. - Today: Digital data and computer controlled switching.

What are the advantages of a Star Topology of WAN?

- A single connection failure only affects one location. - Shorter data paths between any two sites. - Can be expanded and yet become simple and less costly.

What is the Star Topology of WAN?

- A single site that acts as a central connection point. - Can separate data routes between any two sites.

How flexible is the Tiered Topology?

- Allows many variations. - Requires careful considerations which are in the terms of decisions of geography ,usage patterns and growth potential.

What is it based on?

- Based on coaxial cable wiring used for TV signals. Which is its theoretical transmission speeds up to 100 Mbps downstream; 20 Mbps upstream. - Real transmission provides speeds 10 Mbps downstream; 3 Mbps upstream. Transmission limited(throttled) and shared physical connections.

What are the characteristics of ADSL?

- Can establish TCP connection. - Transmit through DSL modem. Internal or External. Splitter separates incoming voice and data signals. May connect to switch or router. - DSL modem forwards modulated signal to local loop. Signal continues over four-pair UTP wire. Distance less than 18,000 feet which a signal combined with other modulated signals in a telephone switch. - Carrer's remote switching facility. Splitter separates data signal from voice signals. Request sent to DSL Access Multiplexer(DSLAM). REquest issued from carrier's network to internet backbone.

What are the uses of T1?

- Connects to branch offices and connects to carrier. - Connects to the telephone company COs and ISPs.

What characteristics does the Ring Topology of WAN contain?

- Each site connected to two other sites to form a ring pattern. - Connects locations rather than local nodes. - Relies on redundant rings which can be rerouted upon site failure. - Can be expanded yet difficult and expensive.

What characteristics does the Bus Topology of WAN contain?

- Each site connects serially to two sites maximum. - Each site depends on every other site to transmit and receive traffic. - Different locations connected to another through point-to-point links.

What is the characteristic of Symmetrical?

- Equal capacity for upstream and downstream data. - Examples: HDSL, SDSL and SHDSL. - Best use: Uploading and downloading significant data amounts.

What is a Full-mesh WAN and its drawback?

- Every WAN site that is directly connected to every other site. - Drawback: Costly.

What does an Incoming and Outgoing T-carrier lines do?

- Incoming T-carrier lines does a multiplexer that separates combined channels. - Out going T-carrier lines does a multiplexer that combines multiple LAN signals.

What is the Mesh Topology of WAN?

- Incorporates many direct interconnected sites. - Data travels directly from origin to destination. - Routers can redirect data easily and quickly.

What is a Cable Modem?

- Modulates, demodulates transmission and reception signals via cable wiring. - Operates at Physical and Data Link layer. - May connect to connectivity device.

What is the characteristic of Asymmetrical?

- More throughput in one direction. - Downstream throughput higher than upstream. - Best use: Video conferencing and web surfing.

What are the characteristics of a Digital Subscriber Line(DSL)?

- Operates over PSTN - Directly competes with T-1 and broadband cable. - Requires repeaters for longer distances which is best suited for WAN local loop. - Supports multiple data, voice channels in over a single line. - Uses advanced data modulation techniques which are the data signal alters carrier signal properties, amplitude or phase modulation.

What are the advantages of those virtual circuits?

- Pay for only the amount of bandwidth required. - Less expensive than other WAN technologies.

What is the Tiered Topology of WAN?

- Sites that are connected in star or ring formations which are interconnected at different levels. - Interconnection points are organized into layers which form hierarchical groupings.

Why are T3's expensive?

T3 provides 28 TIMES more data throughput.

What is a or are Medium(s)?

Telephone wires, fiber-optic cables and wireless links.

Out of all the Topologies for WAN, which is the MOST fault-tolerant WAN type?

The Mesh Topology is the MOST fault-tolerant topology.

How is a single channel divided into multiple channels?

The channels are divided by Time Division Multiplexing(TDM) over two wire pairs.

What are the two types of virtual circuits?

The two types are as follows: - Switched Virtual Circuit(SVC). - Permanent Virtual Circuit(PVC).

What are the uses of T3?

The use of T3 is only for data-intensive businesses.

How many Variants does xDSL refer?

There are six variants. ADSL, G.Lite, HDSL, SDSL, VDSL and SHDSL.

How many types of DSL and what are they called?

There are two types of DSL. Modulation, Capacity and Maximum Line Length.

What is a Permanent Virtual Circuit(PVC)?

They are connections that are established before data needs to be transmitted and are maintained after transmission.

What is a Switched Virtual Circuit(SVC)?

They are connections that are established when parties need to transmit, then terminated after transmission is complete.

What are Frame Relay used for today?

Today, Frame Relays are used as the Data Link protocol for various circuit interfaces and media.

What is the best use for Cable?

Web surfing or network data downloads.