VoIP Overview Flashcards
Provides IP endpoints for voice communications.
IP Phones
Provides Call Admission Control (CAC), bandwidth control and management, and address translation.
Gatekeeper
Interfaces with public switched telephone networks (PSTNs) and VoIP networks. They also provide physical access for local analog and digital voice devices, such as telephones, fax machines, key sets, and private branch exchanges (PBX).
Gateway
Provides real-time connectivity for participants in multiple locations to attend the same videoconference or meeting.
Multipoint Control Unit (MCU)
Provides call control for IP phones, CAC, bandwidth control and management, and address translation. Unlike a gatekeeper, which in a Cisco environment typically runs on a router, a call agent typically runs on a server platform. Cisco Unified Communications Manager is an example of a call agent.
Call Agent
Provide services such as voicemail, unified messaging, and Cisco Communications Manager Attendant Console.
Application Servers
Provides access for end-user participation in videoconferencing. Also contains a video capture device for video input and a microphone for audio input. A user can view video streams and hear audio that originates at a remote user station.
Videoconference station
Required VoIP functionality includes these functions:
Signaling
Database services
Bearer control
Codecs
Known also as triple-play services networks, are networks that can transmit data, voice, and video, or any combination of these services over the same networks
Converged Network
The set of techniques that are used to manage network resources by controlling the bandwidth, delay, delay variation (jitter), and packet loss parameters.
Quality of Service (QOS)
Cisco collaboration components can be organized into five areas:
Infrastructure
Call Control
Collaboration applications (IM and Presence, Voice messaging and Customer contact)
Conferencing (Cisco Webex, Cisco Meeting Server)
Endpoints (Phones, Cisco TelePresence and Software clients)
An action sequence formed by a series of images, and each image in the series succeeds the previous one in the timeline of the action sequence to be displayed
Video Frame
A process by which the overall size of the video information is compacted
Compression in IP Video Solutions
Compression reduces the video size so that it can be transmitted more easily. The primary compression methods for IP video are?
Lossless
Lossy
Both video compression methods can use the following techniques to reduce the video size so that it can be transmitted more efficiently:
Intraframe
Interframe
IP video compression produces, on the decompression end, an exact copy of the image that was originally submitted at the input of the compression process. Lossless video compression is rarely used in IP video solutions, because it creates a large quantity of information that poses difficulties for streaming.
Lossless
Video compression is based on the premise that not all the video information is relevant or capable of being perceived by the viewer. Therefore, some video information is intentionally discarded during the compression process.
Lossy
This technique consists of compressing the contents of a single video frame at a time, without considering previous or succeeding video frames.
Intraframe
Is a complete image, like a JPG or BMP image file.
I‑frame (intracoded picture)
Holds only the changes in the image from the previous frame
P‑frame (predicted picture)
Saves even more space by using differences between the current frame and both the preceding and following frames to specify its content.
B‑frame (bidirectional predicted picture)
The key features of Cisco TMS include the following:
Scalable provisioning Centralized administration Flexible scheduling One-Button-to-Push (OBTP) Phone book management
