Ip Video Brochure

IP VIDEOCONFERENCING—AT-A-GLANCE Courtesy of Cisco Enterprise Marketing WHY SHOULD I CARE ABOUT IP VIDEOCONFERENCING? Traditional videoconferencing consisted of room-based systems that connected to other room-based systems via satellite or ISDN connection. These fixed systems were expensive and proprietary and provided little flexibility or data sharing capability. Even with these limitations, videoconferencing provided an alternative to traveling to remote sites for meetings. Alternatively, IP videoconferencing can be conducted from any PC or connected location, and provides application sharing and whiteboard capabilities cheaply and effectively over corporate and public IP networks.

VIDEOCONFERENCING EQUIPMENT End points: The cameras, microphones, and application sharing tools that people use to participate in an IP videoconference. Sometimes, end points are as simple as inexpensive cameras and microphones connected to a PC.

H.323 and Legacy Room Systems

Multipoint conference unit (MCU): Allows multiparty conferences of three or more participants MCU

H.323 Desktop

H.323–H.320 Video Gateway: Allows communication between H.323 and H.320 (legacy) video terminals

IP Videoconferencing

Video Conference

GK

GW Gatekeeper: Address resolution bandwidth management

Proxy: Traffic classification security

MCM Proxy

H.323 The H.323 protocol was developed specifically for multimedia communications over a packet switched network. Multimedia in this case refers to audio, video, and general data communication. H.323 has many benefits including: Conference Manager With videoconferencing, all parties can see each other at the same time. With conference management, all parties can also view and manipulate applications. WHAT PROBLEMS NEED TO BE SOLVED? Bandwidth: IP Videoconferencing requires a great deal of bandwidth. A LAN will typically have sufficient bandwidth to accommodate IP videoconferencing, so the WAN and the physical connection to the WAN are the critical constraints. QoS: Regardless of the amount of bandwidth available, it is always preferable to employ quality of service (QoS) design practices. Most networks are intentionally over-provisioned, but even those that are not are prone to instantaneous congestion. A good QoS design is one of the best ways to most efficiently use the available bandwidth. Legacy systems: Many legacy systems are still in use today. The migration strategy for converting to an IP videoconferencing system must take legacy systems into account.

• Standardized compression of audio and video allowing multivendor equipment and support

SINGLE ZONES When gatekeepers are present in the network, all video end points and equipment must register with the closest gatekeeper which controls traffic on the network. Each cluster of terminals and equipment controlled by a single gatekeeper comprise a zone. Once defined, the gatekeeper acts as the central point for all calls within its zone, providing Zone 1 H.323 address resolution, Gatekeeper Terminals admission control, and call control GK H.323 services to regisMCU QoS Enabled Terminal IP WAN tered end points. GW A single zone is suitable for small to medium-sized campuses or for several small WAN separated campuses.

• Bandwidth management features T.120 The T.120 protocols define the methods for document conferencing and application sharing (also known as data conferencing) within a multimedia conference. The standards specify how to efficiently and reliably distribute files and graphical information in real time during a multipoint, multimedia meeting. T.120 ensures interoperability between end terminals in the absence of prior knowledge about the other terminals. The standard also allows data sharing applications such as white boards, graphic displays, and image exchanges. ZONES If a network has no gatekeepers, end points may directly call each other if the network addresses are known. This approach requires a full-mesh design and is only suitable for very small networks.

ISDN

H.320 Video Unit

MULTIPLE ZONES For large campuses or WAN separated campuses with multiple endpoints, a multizone solution is required. Intra-zone communication follows the same procedure as a single zone solution. However, for communication across different zones, the gatekeepers of each zone must establish a communication link. Zone 2

H.323 Terminals

Gatekeeper Proxy

Zone 1

GK

Gatekeeper Proxy

QoS Enabled IP WAN

MCU GW

• Hardware or operating system independence • Efficient use of bandwidth with multipoint conferencing (multicast)

H.323 Terminal

Gateway

MCU

Gateway

MCU ISDN

GK

H.320 Video Unit

GK Gatekeeper Proxy

H.323 Terminals Zone 3

MCU MCU

H.323 Terminals

More complex networks require a hierarchical gatekeeper scheme in order to provide end-to-end connectivity for all gateways and terminals. The higher-level gatekeeper is known as a directory gatekeeper. The diagrams below illustrate the importance of the directory gatekeeper with regards to network efficiency and simplicity. Gateway

Gatekeeper

Directory Gatekeeper Multiple Gatekeepers

Multiple Gatekeepers with Directory Gatekeeper

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