For the following options, which International Telecommunication Union (ITU) standard provides a framework for multimedia protocols for the transport of voice, video, and data over packet- switched networks?
A. Weighted fair queuing (WFQ)
C. Voice over IP (VoIP)
D. Session Initiation Protocol (SIP)
Correct Answer: B
Section: Voice Video Explanation
VoIP Control and Transport Protocols
A number of different protocols are used in a VoIP environment for call control, device provisioning, and addressing.
Figure 14-15 shows those protocols focused on VoIP control and transport.
Some of the most significant protocols are:
Dynamic Host Configuration Protocol (DHCP): Used to provide device configuration parameters such as IP configuration (address, subnet mask, default gateway) and TFTP servers (via DHCP option 150).
TFTP: To obtain ring tones, backgrounds, configuration files, and firmware files.
Skinny Client Control Protocol (SCCP): Used for call control for Cisco IP phones (Cisco proprietary).
Real-time Transport Protocol (RTP): For voice stream (VoIP) station-to-station traffic in an active call.
Real-time Transport Control Protocol (RTCP): For RTP control and reporting (accompanying stream to RTP between endpoints).
Media Gateway Control Protocol (MGCP): A client/server protocol for control of endpoints and gateways. In the MGCP model, intelligence resides on the call agent (server), and the device is controlled by the agent.
H.323: An ITU standard for VoIP networks that is a peer-to-peer system (call processing logic is local to each device) used for gateways and endpoints.
Session Initiation Protocol (SIP): A standard for VoIP networks defined by the IETF and used for gateways and endpoints. SIP is feature rich (native IM, presence, and video support),lightweight, and designed for easy troubleshooting (ASCII-based messages).
Which feature will not transfer packets when there is silence?
A. Ear and mouth (E&M)
B. Voice Activity Detection (VAD)
C. Digital Silence Suppressor (DSS)
D. Dial peers
Correct Answer: B
Section: Voice Video Explanation
VAD – Voice Activity Detection
As we listen and pause between sentences, typical voice conversations can contain up to 60 percent
silence in each direction. In circuit-switched telephone networks, all voice calls use fixed bandwidth 64-kbps
links regardless of how much of the conversation is speech and how much is silence. In multiservice
networks, all conversation and silence is packetized. Using VAD, you can suppress packets of silence.
Silence suppression at the source IP telephone or VoIP gateway increases the number of calls or data
volumes that can be carried over the links, more effectively utilizing network bandwidth. Bandwidth savings
are at least 35 percent in conservative estimates. VAD is enabled by default for all VoIP calls. In real-world
practice, is it suggested that VAD be avoided because it creates quality issues and breaks applications
such as fax and modem transmissions. For G.729 bandwidth is reduced from 26.4 kbps to 17.2 kbps with
VAD and to 7.3 kbps with VAD and cRTP enabled.
Cisco Press CCDA 640-864 Official Certification Guide Fourth Edition, Chapter 14
What does the Cisco SLM define as the component used to specify expected performance between a pair of devices connected by a network?
Correct Answer: C
Section: Management – Operations Explanation
CiscoWorks Service Level Manager
Service Level Manager (SLM) version 2.0 is the server component of the CiscoWorks Service Management Solution (SMS). SLM allows administrators to define and validate service-level agreements in terms common to those written into their Service Provider contract. Through local and remote Collection Managers, SLM interacts with the Cisco IOS. Software to perform synthetic testing and monitoring of Layer 3 and 4 services according to the specified SLA parameters and thresholds. The synthetic testing approach ensures a common understanding between customer and service provider of the endpoints, characteristics, and thresholds of the tests.
NOTE. This product is no longer being sold and might not be supported. View the End-of-Life http://www.cisco.com/en/US/products/sw/cscowork/ps2144/index.html
In a network with Enhanced Interior Gateway Routing Protocol (EIGRP) and IGRP using the same autonomous system number, what will happen on the router configured with both protocols?
A. Redistribution occurs automatically.
B. Redistribution is not necessary.
C. EIGRP assumes IGRP is a less capable protocol and overtakes it.
D. Redistribution does not occur automatically.
Correct Answer: A
Section: Routing Explanation
What is the acronym PDIOO short for?
A. Purpose, design, install, operation, optimization
B. Purpose, design, implement, operate, optimize
C. Plan, design, install, operation, optimization
D. Plan, design, implement, operate, optimize
Correct Answer: D
Section: Design Explanation
PDIOO has now been replaced with PPDIOO
Cisco Press CCDA 640-864 Official Certification Guide Fourth Edition, Chapter 1 (Page 15)
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