Lect 1 Wan Overview

Question 1

Differences btn WAN and LAN?

Answer 1

1. Wan occupy large area
2. Wan controlled by multiple organizations/LAN single admin
3. Lans have high speed connections.
4. Wan carries multiple services btn many sites.
5. Wan are owned by service providers, Lan owned by organizations.

Question 2

4 WAN topologies

Answer 2

1. Point to point.
2. Hub-and-spoke.
3. Full Mesh.
4. Dual homed technology.

Question 3

Point to point

Answer 3

Involves leased line connection btn two end points transparent to customer’s network.

Question 4

Hub and Spoke

Answer 4

Single interface to the hub can be shared by spoke ckts which are connected using virtual ckts.

Question 5

Full mesh

Answer 5

Sites can communicate with any other site directly using virtual ckts.

Question 6

Dual homed

Answer 6

Provides a redundancy & load balancing tho expensive to implement.

Question 7

Layers that WAN operates?

Answer 7

Layer 1 and 2 -> Physical and Data link Layers

Question 8

Data Terminal Equipment - DTE

Answer 8

Customer devices that pass data from a customer net for transmission over the WAN.

Question 9

Demarcation point

Answer 9

Point in a building to separate customer equipment from service provider equipment.

Question 10

Local loop/Last mile

Answer 10

Copper or fiber cable connecting CPE to the Central Office CO of service provider.

Question 11

Central Office CO

Answer 11

Local service provider facility/building that connects CPE to the provider network.

Question 12

Toll network

Answer 12

Consists long haul, all-digital, fiber optic communication lines and other equipments inside WAN network.

Question 13

Dialup modem

Answer 13

Tech that converts digital signals into voice frequencies transmitted over analog lines of public telephone network.

Question 14

Access Server

Answer 14

Tech that controls and coordinates dialup modem, dial-in and dial-out user communications.

Question 15

Broadband Modem

Answer 15

Type of digital modem used with high speed DSL or cable internet service.

Question 16

Channel Service Unit CSU

Answer 16

Provides termination for the digital signal and ensure connection integrity through error correction and monitoring.

Question 17

Data Service Unit - DSU

Answer 17

Converts line frames into frames that the LAN can interpret and vice versa.

Question 18

Core router/multilayer switch

Answer 18

Router or switch that resides within the middle or backbone of the WAN.

Question 19

Circuit-switched network

Answer 19

One that establishes a dedicated ckt/channel btn nodes and terminals b4 users communicate.

Question 20

Common types of Circuit Switched Network

Answer 20

1. Public Switched Telephone Network (PSTN)
2. Integrated Services Digital Network (ISDN)

Question 21

Packet-switched network

Answer 21

One that splits traffic data into packets that are routed over a shared network.

Question 22

Packet switched net link determination approach

Answer 22

1. Connectionless eg internet
2. Connection oriented systems eg frame relay

Question 23

WAN link connection options

Answer 23

1. Public - internet - broadband vpn - e.g DSL Cable wireless.
2. Private
   i. Dedicated - leased lines e.g T1/E1 and T3/E3.
   ii. Switched
   
   • Pkt Switched e.g MPLS, ATM.
   • Ckt Switched e.g PSTN, ISDN.

Question 24

Two types of ISDN interface

Answer 24

1. Basic Rate Interface - BRI
2. Primary Rate Interface - PRI

Question 25

BRI

Answer 25

Provides two 64 Kb/s bearer(B) channels for carrying voice and data and a 16 Kb/s delta(D) channel for signaling, call setup and other purposes.

Question 26

PRI

Answer 26

Provides 23 B channels with 64 Kb/s and one D channel with 64 Kb/s for total bit rate of 1.544 Mb/s

Question 27

WAN standards include

Answer 27

1. Physical Adressing
2. Flow Control
3. Encapsulation

Question 28

Delay/Latency

Answer 28

Caused when device processes the frame b4 sending.

Question 29

Jitter

Answer 29

Variation in delay of received packets.

Question 30

Types of Virtual Circuits

Answer 30

1. Switched Virtual Circuit
2. Permanent Virtual Circuit

Question 31

Integrated Services Digital Network (ISDN)

Answer 31

Is a ckt switching tech that enables local loop of a PSTN to carry digital signals thru TDM.

Question 32

Frame Relay

Answer 32

Layer 2 non broadcast multi-access (NBMA) WAN tech used to interconnect enterprise LANs.

Question 33

Asynchronous Transfer Mode(ATM)

Answer 33

Tech capable of transfering voice,video and data thru private and public networks.

Question 34

Multi Protocol Label Switching (MPLS)

Answer 34

Is a multiprotocol high performance WAN tech that directs data from one router to the next.

Question 35

Very Small Aperture Terminal VSAT

Answer 35

Is a solution that creates a private WAN using satellite communications.

Question 36

Digital Subscriber Line DSL

Answer 36

An always on connection that uses existing twisted pair telephone lines to transport high bandwidth data, and provides IP services to subscribers.

Question 37

VPN

Answer 37

Is an encrypted connection between a private net over a public net such as the internet.

Question 38

Benefits of VPN

Answer 38

1. Cost saving
2. Security
3. Scalability
4. Compatibility with broadband technology

Question 39

Two types of VPN access

Answer 39

1. Site to site VPNs
2. Remote Access VPNs

Question 40

Site to site VPN

Answer 40

Connects entire networks to each other. E.g a branch office net to company HQ.

Question 41

Remote access VPNS

Answer 41

Enables mobile users to access company’s net securely over the internet.