642-813 Q&A – Prepare infrastructure to support advanced services (61-65)

Section4 – Prepare infrastructure to support advanced services

QUESTION NO: 61
Refer to the exhibit. Which switch interface configuration command would automatically configure quality of service (QoS) for voice over IP (VoIP) within a QoS domain?
 

A.auto qos voip cisco-phone
B.mls qos trust
C.switchport priority extend cos 7
D.switchport priority extend trust
Answer: A
Explanation:
You can use the auto-QoS feature to simplify the deployment of existing QoS features. Auto-QoS makes assumptions about the network design, and as a result, the switch can prioritize different traffic flows and appropriately use the ingress and egress queues instead of using the default QoS behavior. (The default is that QoS is disabled. The switch then offers best-effort service to each packet, regardless of the packet contents or size, and sends it from a single queue.)
When you enable auto-QoS, it automatically classifies traffic based on the traffic type and ingress packet label. The switch uses the resulting classification to choose the appropriate egress queue.
When you enable auto-QoS by using the auto "qos voip cisco-phone", the "auto qos voip ciscosoftphone", or the "auto qos voip trust" interface configuration command, the switch automatically generates a QoS configuration based on the traffic type and ingress packet label and applies the appropriate commands automatically.

QUESTION NO: 62
Which two statements about WLAN components are true? (Choose two.)
A.Cisco Aironet autonomous access points cannot be supported by the Cisco Unified Wireless Network.
B.Cisco Aironet lightweight access points cannot be supported by the Cisco Unified Wireless Network.
C.In the autonomous access point solution, control is provided by the Wireless Domain Services (WDS).
D.In the autonomous access point solution, control is provided by the WLAN controller.
E.In the lightweight access point solution, WLAN management is provided by the WLAN Solution Engine (WLSE).
F.In the lightweight access point solution, WLAN management is provided by the WLAN Control System (WCS).
Answer: C F

QUESTION NO: 63
Which two Aironet enterprise solution statements are true? (Choose two.)
A. A Cisco Aironet AP handles the transmission of beacon frames and also handles responses to probe-request frames from clients.
B. A Cisco Aironet solution includes intelligent Cisco Aironet access points (APs) and Cisco Catalyst switches.
C. In the Cisco Aironet solution, each AP is locally configured by the use of either a web interface or the command line interface.
D. The Cisco Aironet AP handles real-time portions of the LWAPP protocol, and the WLAN controller handles those items which are not time sensitive.
E. Virtual MAC architecture allows the splitting of the 802.11 protocol between the Cisco Aironet AP and a LAN switch.
Answer: AD

QUESTION NO: 64
Refer to the exhibit. Which statement is true about where trust boundaries should be established in a network?
A.Endpoint 1 is the only acceptable place to establish a trust boundary.
B.Endpoint 1 is the optimal place to establish a trust boundary. Endpoints 2 and 3 are acceptable places to establish a trust boundary.
C.Endpoint 2 is the only acceptable place to establish a trust boundary.
D.Endpoint 2 is the optimal place to establish a trust boundary. Endpoints 1 and 3 are acceptable places to establish a trust boundary.
E.Endpoints 1 and 2 are optimal places to establish a trust boundary. Endpoint 3 is an acceptable place to establish a trust boundary.
F.Endpoints 2 and 3 are optimal places to establish a trust boundary. Endpoint 1 is an acceptable place to establish a trust boundary.
Answer: E
Explanation:
Trust Boundaries:
When connected by a single cable, the IP phone is the edge of the managed network. An integral part of the Cisco network design architecture has always been the classification, or coloring, of traffic as close to the edge of the network as possible. As such, the IP phone can and should classify traffic flows.
Try to maintain the trust boundary in the wiring closet. If necessary, move it down to the distribution layer on a case-by-case basis, but avoid moving it to the core of the network. This advice conforms to the general guidelines for keeping the trust boundary as close to the source as possible.
By default, Cisco IP phones mark all VoIP traffic with CoS =5 and DSCP=46. However, it is critical to make sure that the PC connected to the access port of the IP phone is not also classifying traffic. The recommended method for ensuring this is to extend the trust boundary of the Ethernet switch to the IP phone and not beyond, meaning the IP phone will re-classify all traffic coming from the PC with CoS=0.

QUESTION NO: 65
Which statement is true about utilizing a data network for voice traffic?
A. Adding bandwidth to the data network is the primary solution to provide for the needs of voice traffic.
B. Because voice traffic volume cannot be calculated, network bandwidth requirements must be determined from an existing installation.
C. Voice traffic will require some form of QoS mechanisms in most networks.
D. Voice traffic will require some form of QoS implementation only in congested networks.
E. Network congestion must be totally e
Answer: C
Explanation:
For VoIP to be a realistic replacement for standard public switched telephone network (PSTN) telephony services, customers need to receive the same quality of voice transmission they receive with basic telephone services-meaning consistently high-quality voice transmissions. Like other real-time applications, VoIP is extremely bandwidth- and delay-sensitive . For VoIP transmissions to be intelligible to the receiver, voice packets should not be dropped, excessively delayed, or suffer varying delay (otherwise known as jitter).
VoIP can guarantee high-quality voice transmission only if the voice packets, for both the signaling and audio channel, are given priority over other kinds of network traffic. For VoIP to be deployed so that users receive an acceptable level of voice quality, VoIP traffic must be guaranteed certain compensating bandwidth, latency, and jitter requirements. QoS ensures that VoIP voice packets receive the preferential treatment they require. In general, QoS provides better (and more predictable) network service by providing the following features:

Supporting dedicated bandwidth
Improving loss characteristics
Avoiding and managing network congestion
Shaping network traffic
Setting traffic priorities across the network