Day 4

Question 1

multiplexing

Answer 1

the process of combining and transmitting multiple analog or digital signals via a single transmission medium

Question 2

Time Division Multiplexing (TDM)

Answer 2

the process of combining analog or digital signals with each signal having its own timeslot to transmit or receive data via a single carrier.

Question 3

Frequency Division Multiplexing (FDM)

Answer 3

the process of combining analog or digital signals with each signal having its own frequency to operate within

Question 4

Wave Division Multiplexing (WDM)

Answer 4

a method of multplexing data from two or more inputs and transmitting them over the same fiber-optic cable where each input is propagated on its own wavelength (color)

Question 5

Time division multiple access (TDMA

Answer 5

a satelite and cellular technology that interweaves multiple digital signals by dividing each channel into sub-channels, providing service to multiple users simultaneously.
each user is given a timeslot to transmit and receive data

Question 6

Code Division Multiple Access (CDMA)

Answer 6

data is spread out over the entire available bandwidth of the carrier.
the data is sent in small pieces over a number of discrete frequencies .
bandwidth on the carrier is spread by means of a coder

Question 7

Types of circuits used in WAN’s

Answer 7

point to point, packet switched, and circuit switched

Question 8

point to point (pt2pt)

Answer 8

a communications path that is a direct connection between two endpoints.
can be expensive.
the line is reserved 24/7

Question 9

circuit switching

Answer 9

a networking method that establishes a fixed path between the transmitting and receiving stations.
multiple circuits connect together to establish a path for the communication.
(similar to old school telephone networks)

Question 10

packet switching

Answer 10

a technology based on transmitting packets via multiple paths at the same time

Question 11

WAN protocols

Answer 11

Key protocols include HDLC, PPP, X.25, and Frame relay

Question 12

High-level data link control (HDLC)

Answer 12

an encapsulation method for data on serial links that will not encapsulate multiple protocols on the same link, so you cannot identify the type of protocol being carried.
each vendor develops their own proprietary HDLC for their own equipment

Question 13

Frame Check Sequence

Answer 13

provides a method for the receiving device to determine if the frame experienced transmission errors

Question 14

Point-to-point protocol (PPP)

Answer 14

allows users to connect to IP networks using modems or dedicated leased lines.
PPP encapsulates the network layer protocol.
PPP is relatively slow.
PPP is non proprietary and is used to connect WAN links when equipment is purchased from different vendors.

Question 15

frame relay

Answer 15

a packet switching technology.
frame relay provides for dynamic-bandwidth and congestion control features with the use of forward explicit congestion notificaiton (FECN) and backward explicit congestion notification (BECN)

Question 16

Forward Explicit congestion notification (FECN)

Answer 16

transmitted source terminal requesting the destination terminal slow down its requests for data

Question 17

Backward explicit congestion notification (BECN)

Answer 17

transmitted by destination terminal requesting the source terminal send data more slowly

Question 18

Committed information rate (CIR)

Answer 18

congestion control with frame relay works by providing a guaranteed minimum bandwidth for each user

Question 19

x.25

Answer 19

one of the oldest packet-switched services available and developed before OSI model.
Used by ATM’s in the 1980’s.
Required a PAD to operate.

Question 20

Packet assembler/disassembler (PAD)

Answer 20

used to perform buffering of data, packet assembly, and packet disassembly when network devices are too simple to implement full x.25 functionality

Question 21

Multi-Protocol Label Switching (MPLS)

Answer 21

considered a layer 2.5 technology.
allows routers to label data and use specific connection paths.
The entry and exit point of an MPLS domain are Label Edge Routers (LER’s), which add and remove labels.
Label Switch Routers (LSR’s) are routers that simply forwards traffic based on label information.

Question 22

Internet Control Message Protocol (ICMP)

Answer 22

an error reporting mechanism for the IP protocol.

sends error reports back to the originator of the datagram.

Question 23

PING

Answer 23

a utility that uses ICMP the messages Echo and Echo reply to request a response from a remote host to verify if it is available for communication.

• t: continue pinging until interrupted with a CTRL+C
• l: set the size of the ping packet

Question 24

Traceroute

Answer 24

uses ICMP to send messages then uses the returning ICMP Time Exceeded error messages to identify routers from source to destination.
the Windows command to use Traceroute is tracert

Question 25

Internet Group Management Protocol (IGMP)

Answer 25

a protocol used with IP multicast. multicast addresses are assigned based on traffic type, not individual hosts.
If a specific multicast service is desired, a host notifies the upstream router or switch that they want to receive it. .
This notification gives the requesting device group membership.

Question 26

Transport Layer Protocols

Answer 26

handle data delivery between computers.

rely on ports for proper communication, which reference application layer protocols

Question 27

Transmission Control Protocol (TCP)

Answer 27

reliable, connection oriented transport layer protocol

Question 28

TCP Three-way handshake

Answer 28

used to establish a logical connection prior to the transmission of data.
Step 1: the initiating computer sends a SYN message
Step 2: the destination computer acknowledges with a SYN/ACK message
Step 3: the initiating computer sends its own acknowledgement ACK message.

Question 29

User Datagram Protocol (UDP)

Answer 29

an unreliable, connectionless protocol that does not guarantee data transmission.