Question 1.
What Layer 2 encapsulation is used for POS?

a) POS uses HDLC encapsulation at Layer 2.
b) POS uses PPP encapsulation at Layer 2.
c) POS can use any standard Layer 2 encapsulation protocol at Layer 2.
d) POS does not require any Layer 2 encapsulation protocol at Layer 2.

Answer

Question 2.
What QoS can ATM deploy for voice traffic with VoIP technology?

a) ATM can deploy its native QoS.
b) ATM can deploy various queuing algorithms to prioritize voice traffic.
c) ATM cannot deploy any QoS parameters for voice traffic.
d) ATM cannot deploy its native QoS parameters to distinguish voice traffic.

Answer

Question 3.
How does ATM handle compressed voice?

a) ATM cannot handle compressed voice.
b) AAL2 is used to handle compressed voice.
c) AAL1 is used to handle compressed voice.
d) ATM handles compressed voice when it is encapsulated into IP packets.

Answer

Answers

Question 1.
What Layer 2 encapsulation is used for POS?

a) POS uses HDLC encapsulation at Layer 2.
b) POS uses PPP encapsulation at Layer 2.
c) POS can use any standard Layer 2 encapsulation protocol at Layer 2.
d) POS does not require any Layer 2 encapsulation protocol at Layer 2.

Answer
b) POS uses PPP encapsulation at Layer 2.

Explanation
POS uses PPP encapsulation at Layer 2 as specified in RFC 2615. HDLC is a proprietary protocol that is deployed within a vendor-specific environment, be it Cisco or something else. There must be a Layer 2 encapsulation since SONET is Layer 1. This leaves PPP as the correct answer, especially since PPP is a standard.
[3568]

Question 2.
What QoS can ATM deploy for voice traffic with VoIP technology?

a) ATM can deploy its native QoS.
b) ATM can deploy various queuing algorithms to prioritize voice traffic.
c) ATM cannot deploy any QoS parameters for voice traffic.
d) ATM cannot deploy its native QoS parameters to distinguish voice traffic.

Answer
d) ATM cannot deploy its native QoS parameters to distinguish voice traffic.

Explanation
The reason ATM cannot deploy its native QoS parameters for voice traffic is because in VoIP technology voice traffic is encapsulated into IP. So, ATM will simply treat it as data, which is how it treats any other IP traffic. However, ATM does provide its QoS to voice traffic when it is presented to ATM directly.

ATM can indirectly provide QoS to VoIP if the IP paths are manually traffic-engineered over ATM circuits.
[3569]

Question 3.
How does ATM handle compressed voice?

a) ATM cannot handle compressed voice.
b) AAL2 is used to handle compressed voice.
c) AAL1 is used to handle compressed voice.
d) ATM handles compressed voice when it is encapsulated into IP packets.

Answer
b) AAL2 is used to handle compressed voice.
d) ATM handles compressed voice when it is encapsulated into IP packets.

Explanation
When voice is positioned directly over ATM, AAL2 is used to handle compressed voice. On the other hand, VoIP technology typically compresses voice into IP. Thus VoIP over ATM over AAL5 also allows ATM to handle compressed voice.
[3570]