Section 10: Wide Area Network (WAN)

Question 1

WAN Connection Type: Dedicated Leased Line

Answer 1

Know for Exam: T1 and E1 are dedicated leased lines that use CSU/DSU modem to connect.

▪ Logical connection that connects two sites through a service provider’s facility or telephone company’s central office
▪ More expensive than other WAN technologies because a customer doesn’t share bandwidth with other customers
(Examples: T1, E1, T3, and E3 circuits)
Digital circuits are measured in 64-kbps channels called Digital Signal 0 (DS0)

Question 2

WAN Connection Type: Circuit-Switched Connection

Answer 2

▪ Connection is brought up only when needed, like making a phone call
▪ On-demand bandwidth can provide cost savings for customers who only need periodic connectivity to a remote site
(Example: ISDN)

Question 3

WAN Connection Type: Packet-Switched Connection

Answer 3

▪ Always on like a dedicated leased line, but multiple customers share the bandwidth
▪ SLAs used to guarantee a certain quality (5mbps at least 80% of the time)
▪ Virtual circuits (represented as dashed lines)
(Example: Frame Relay)

Question 4

T1 Speed
T3 Speed
E1 Speed

Answer 4

T1 = 1.544 Mbps
T3 = 44.736 Mbps
E1 = 2.0 Mbps

Question 5

Metro Ethernet

Answer 5

Technology used by service provider is hidden from customer and they only need to connect their network’s router to a Smart Jack

Question 6

PPP

Answer 6

Point-to-point Protocol
▪ Commonly used Layer 2 protocol on dedicated leased lines to simultaneously transmit multiple Layer 3 protocols (IP, IPX)
▪ Each Layer 3 control protocol runs an instance of PPP’s Link Control Protocol (LCP)

Question 7

PPP Authentication Methods

Answer 7

For Exam: PAP credentials are sent as clear text.
CHAP and MS-CHAP credentials are hashed.

PAP - Password Authentication Protocol
CHAP - Challenge-Handshake Authentication Protocol: one-way authentication using a three-way handshake.
MS-CHAP - Microsoft-Challenge-Handshake Authentication Protocol: two-way authentication using a three-way handshake.
**B

Question 8

PPPoE

Answer 8

Point-to-Point Over Ethernet

Question 9

HFC

Answer 9

Hybrid Fiber-Coax Distribution (Cable Network/Modems)

Question 10

DOCSIS

Answer 10

Data-Over-Cable Service Interface Specification (Cable Modems)

Question 11

POTS

Answer 11

Plain Old Telephone Service
Runs on Public Switched Telephone Network (PSTN)

Question 12

ATM

Answer 12

Asynchronous Transfer Mode - Fixed-length cells of 53-bytes (48-byte payload and 5-byte header)
(Fiber and SONET networks)

▪ Layer 2 WAN technology operating using Permanent Virtual Circuits (PVCs) and Switched Virtual Circuits (SVCs)
▪ Similar to Frame Relay, except all frames are transferred as fixed-length (cells)

Question 13

Bandwidth Speeds to Know:
Frame Relay
T1
T3
E1
E3
(Fiber)
ATM
SONET

Answer 13

Frame Relay = 56K - 1.544 M
T1 = 1.544M
T3 - 44.736M
E1 = 2.048M
E3 = 34.4M
(The next two are over Fiber)
ATM = 155M - 622M
SONET= 51.94M (OC1) - 159.25G (OC3072)

Question 14

SDWAN

Answer 14

Software-Defined Wide Area Network
If an organization with many branch offices and trying to move more to cloud services then may need SDWAN.

Question 15

mGRE

Answer 15

A protocol that can be used to enable one node to communicate with many other nodes, essentially creating a point to multipoint link
▪ Usually combined with the Dynamic Multipoint VPN, or DMVPN, protocol, as well, for security