Deck 12: Wide Area Network

Question 1

Which statement is correct about the Frame Relay technology?

A) It uses switched virtual circuits for data delivery.
B) It is a technology designed for the leased line WAN service.
C) It comes with an error discovery and recover function during packet delivery.
D) Its frames have a high overhead and thus slow in the delivery of WAN frames.
E) It is much used for "both" data and voice services.

Answer 1

E

Question 2

Which may NOT be a server provider facility (SPF) in WAN connectivity?

A) Central Office (CO)
B) Point of Presence (POP)
C) Access link
D) WAN Backbone network
E) Border router on the customer premise

Answer 2

E

Question 3

SONET and T-carrier (e.g., T-1) standards are defined at the ________ layer.

A) data link
B) transport
C) physical
D) network
E) session

Answer 3

C

Question 4

The following are general attributes of the PSDN (Packet Switched Data Network) EXCEPT:

A) With capacity sharing, more clients can be served using the same network capacity.
B) PSDN is more flexible than leased lines in meeting customer demands (e.g., bandwidth).
C) PSDN can be utilized for voice and data communications.
D) WAN frames, each containing an IP packet, are multiplexed at local POPs and transported over the cloud's trunk links.
E) PSDN generally depends on the reliable transmission in data link for which transmission errors are detected and corrected.

Question 5

The technological details of Frame Relay as a WAN standard are defined at the ______ layer.

A) application
B) transport
C) network
D) data link
E) physical

Question 6

What is a popular data link protocol introduced for end-to-end leased lines?

A) PPP (Point-to-Point)
B) Frame Relay
C) ATM (Asynchronous Transfer Mode)
D) Carrier Ethernet
E) MPLS (Multi-Protocol Label Switching)

Question 7

Imagine that a firm has four offices and the business locations are fully meshed with T-1 lines. This results in ___ WAN connections.

A) 0
B) 1
C) 4
D) 6
E) 12

Question 8

Which ATM Quality of Service category should deliver data in the highest priority?

A) Available bit rate
B) Variable bit rate
C) Unspecified bit rate
D) Constant bit rate
E) All categories deliver data with the same priority

Question 9

Which correctly orders the level of redundancy from low to high as WAN topologies?

A) hub and spoke - full mesh - partial mesh
B) hub and spoke - partial mesh - full mesh
C) partial mesh - full mesh - hub and spoke
D) full mesh - partial mesh - hub and spoke
E) partial mesh - hub and spoke - full mesh

Question 10

Which WAN technology defines the transmission speed in terms of the OC (optical carrier) hierarchy?

A) Ethernet
B) SONET
C) Frame Relay
D) Cable
E) T-carrier

Question 11

Choose an INCORRECT statement regarding the MPLS technology.

A) It is a solution to fast forward IP packets using a mechanism similar to layer 2 switching rather than layer 3 routing.
B) In order to forward IP packets, MPLS relies on the label, conceptually similar to the virtual circuit.
C) When MPLS is active, routers utilize both label information base (LIB) and their routing tables to move packets.
D) The MPLS-enabled router is called Label Switching Router.
E) The label assigned to an IP packet changes while going through each router.

Question 12

The customer network can use a ______ to access the Frame Relay network of a carrier.

A) router
B) ATM access
C) switch
D) bridge
E) DSL modem

Question 13

Choose the LEAST accurate statement.

A) In circuit switching, transmission capacity is guaranteed/reserved between two points.
B) Packet switching generally guarantees network performance (ex. speeds).
C) Packet switching service only charges a customer for the capacity actually used.
D) Packets travelling between two end nodes may not take the same delivery path.
E) With packet switching, WAN capacity can be dynamically shared by customers.

Question 14

A company has ten offices nationwide. What is the minimum number of leased lines needed if the company interconnects all of its distributed offices through a packet switched data network?

A) One
B) Five
C) Ten
D) Twenty
E) cannot say

Question 15

The service level agreement (SLA) for a WAN service may include following terms EXCEPT:

A) Penalty provisions for service failures
B) LAN topology of a client's enterprise network
C) Data rate (speed) of a subscribed WAN service
D) Latency (ex. round-trip transmission delay) and how it is measured
E) Availability of network service and its calculation method

Question 16

Which of these is NOT considered as customer premises equipment (CPE) in WAN connectivity?

A) Cable modem
B) CSU/DSU (Channel service unit/Data service unit)
C) Router
D) Local access link
E) All of the above are CPE.

Question 17

Which represents INCORRECT description of the demarcation point?

A) It is a point where Customer Premises Equipment meets Service Provider Facility.
B) It is generally placed at the WAN service provider's point of presence.
C) It becomes a dividing point of network maintenance responsibility.
D) At a house, the junction box is called Network Interface Device.
E) At a business-occupied building, the building entrance facility becomes the demarcation point.

Question 18

The packet switched data network (PSDN) runs on following technology standards EXCEPT

A) Frame-Relay
B) Carrier Ethernet
C) Multi-Protocol Label Switching
D) Asynchronous Transfer Mode
E) Point-to-Point (PPP)

Question 19

Choose a CORRECT statement on WAN links.

A) The T-1 circuit at the physical layer can carry only PPP (point-to-point) data link layer frames.
B) The T-1 circuit at the physical layer can carry only PSDN (ex. Frame Relay) data link layer frames.
C) It is possible that one data link frame (ex. Frame Relay) is encapsulated within another data link frame (ex. ATM) for delivery.
D) The border router that connects to a WAN link does NOT need to have LAN connectivity.
E) WiMax and Satellite technologies are designed for "narrowband" wireless communications.

Question 20

Frames produced by the ATM standard are known as:

A) packets
B) cells
C) clusters
D) virtual circuits
E) segments

Question 21

Choose an INCORRECT statement on WAN links (do not count the Internet here).

A) A leased line WAN link between two remote routers can become a subnet with its own subnet address.
B) A client company can choose either public IPs or private IPs for the WAN links.
C) If a border router connects to multiple leased lines, a router port is generally dedicated to each leased line.
D) When the WAN link is through the PSDN cloud, the border router at a client site just needs one physical link to the carrier network to connect several remote locations.
E) The leased line WAN link between two remote routers takes advantage of a virtual circuit for data delivery.

Question 22

The following WAN standards rely on virtual circuits EXCEPT:

A) Frame-Relay
B) Carrier Ethernet
C) Multi-Protocol Label Switching
D) Asynchronous Transfer Mode
E) Point-to-Point (PPP)

Question 23

The following frame must be carrying ___________ WAN data?

A) Frame-Relay
B) Carrier Ethernet
C) Multi-Protocol Label Switching
D) Asynchronous Transfer Mode
E) Point-to-Point (PPP)

Question 24

Choose an INCORRECT statement regarding the SONET/SDH technology.

A) SONET/SDH is intended for high speed leased line services on fiber optic cabling.
B) The SONET service is offered on the optical carrier (OC) data rate hierarchy.
C) SONET/SDH uses Time Division Multiplexing to combine lower speed channels to create a bigger pipe.
D) SONET/SDH is widely used by WAN carriers to define the bandwidth of their backbone networks.
E) The SONET infrastructure generally relies on the dual-ring architecture to improve fault-tolerance.

Question 25

Which does NOT represent a leased line service/technology?

A) T1
B) T3
C) SONET
D) E1
E) Frame Relay

Question 26

Which statement is incorrect about the Frame Relay technology?

A) It uses permanent virtual circuits for data delivery.
B) Its popularity has dropped, overtaken by Carrier Ethernet.
C) There is no error control during packet delivery and the correction of transmission errors is left to host stations.
D) It is designed to be low overhead (simple header structure) and therefore efficient in frame delivery.
E) It is available exclusively for data delivery (not for voice) service function.

Question 27

How many different DLCIs (data link connection identifiers) are used for the Frame Relay-based virtual circuit from Houston HQ to Toronto Branch? Assume that the virtual circuit goes through B, C, and D WAN switches.

A) 1
B) 2
C) 4
D) 8
E) 16

Question 28

Below figure must represent the general structure of _______ table maintained by WAN intermediary nodes such as WAN switches.

A) Carrier Ethernet
B) Frame Relay
C) MPLS (Multi-Protocol Label Switching)
D) PPP (Point-to-Point)
E) SONET

Question 29

A firm wants to build a full mesh WAN connections to interconnect its four business locations through AT&T's Frame Relay WAN infrastructure. The client firm needs to order AT&T _____ different virtual circuits.

A) 24
B) 3
C) 4
D) 8
E) 12

Question 30

Which of the following is INCORRECT in describing Carrier Ethernet?

A) Compared with other WAN platforms, service costs of Carrier Ethernet are very competitive.
B) Carrier Ethernet offers high bandwidth such as 100Gbps.
C) Corporate customers can purchase bandwidth incrementally to meet their needs.
D) Carrier Ethernet offers flexible WAN design choices, which include point-to-point and multipoint-to-multipoint connections.
E) A carrier Ethernet's limitation is that clients are unable to build global scale WAN connections.

Question 31

Imagine WAN connections of an enterprise network running on the AT&T's PSDN as follows.


-What IP address-Virtual Circuit mapping information would R1 need to maintain to deliver packets to R2 and R3?
$\begin{array}{|ll|c|}\hline &{\text { IP address of }} & \text {Virtual circuit} \\&{\text { Destination Routers }} & \text { Identifier } \\\hline \text { (1) } & 10.10 .10 .2 & \text { VC1 } \\\text { (2) } & 10.10 .10 .2 & \text { VC2 } \\\text { (3) } & 172.16 .10 .2 & \text { VC3 } \\\text { (4) } & 172.16 .10 .2 & \text { VC4 } \\\text { (5) } & 192.168 .10 .1 & \text { VC5 } \\\text { (6) } & 192.168 .10 .1 & \text { VC6 } \\\hline\end{array}$

A) (1) and (2)
B) (1) and (3)
C) (1), (3), and (5)
D) (1), (2), (3), and (4)
E) (1), (2), (3), (4), (5) and (6)

Question 32

Imagine WAN connections of an enterprise network running on the AT&T's PSDN as follows.


-What is a right entry of the IP address-Virtual Circuit mapping table on R1?
$$\begin{array} { | l c | c | c | } \hline & \begin{array} { c } \text { IP address of } \\\text { Destination Routers }\end{array} & \begin{array} { c } \text { Virtual circuit } \\\text { identifier }\end{array} & \begin{array} { c } \text { Exit interface } \\\text { (or sub-interface) }\end{array} \\\hline \text { A) } & 10.10 .10 .2 & \mathrm { VC } 1 & \mathrm {~S} 0 / 0 / 0.10 \\\text { B) } & 172.16 .10 .0 / 24 & \mathrm { VC } 3 & \mathrm {~S} 0 / 0 / 0.20 \\\text { C) } & 10.10 .10 .2 / 24 & \mathrm { VC } 1 & \mathrm {~S} 0 / 0 / 0 \\\text { D) } & 172.16 .10 .2 & \mathrm { VC } 3 & \mathrm {~S} 0 / 0 / 0 \\\text { E) } & 10.10 .10 .0 / 24 & \mathrm { VC } 1 & \mathrm {~S} 0 / 0 / 0.10 \\\hline\end{array}$$

A) A
B) B
C) C
D) D
E) E

Question 33

The cloud, as an ISP network, is running on the MPLS (multi-protocol label switching) technology.

-Which router(s) need(s) to be MPLS technology-enabled to fast track the packets between the two hosts?

A) All routers
B) R1 and R6 only
C) R2 and R5 only
D) R3 and R4 only
E) R2, R3, R4, and R5 only