• Network Videoconferencing and H.323
  • H.323 is the International Telecommunications Union (ITU) standard for real-time multimedia communications and conferencing over packet-based (IP) networks. Sending videoconferences over standard ISDN lines is expensive and prone to connectivity problems. Because of specialized, dedicated equipment needs, ISDN-based videoconferencing is often restricted to special sites and rooms. Network-based H.323 videoconferencing is the next-generation standard. H.323 is more cost-effective, offering greater flexibility and scalability: wherever there is a LAN connection, H.323 videoconferencing equipment will operate.

• H.323 Network Components
  • The H.323 specification defines a number of new network components that interoperate with other standards-compliant endpoints and networks by virtue of an H.323/H.32X gateway.

• Following are the network components defined by the H.323 standard:

• Terminals are the endpoints on the LAN which provide for real-time, two-way communications. Most H.323 terminals are desktop computers running H.323 compliant software. All terminals must support voice communications while video and data are optional. However, if these other media are supported, H.323 specifies what modes of operation are required so that all terminals supporting video and/or data can work seamlessly together.
• Multipoint Controller Units consist of a required multipoint controller (MC) and an optional multipoint processor or processors. The MC is the conference controller. The MC handles negotiation between all terminals to determine common capabilities and controls conference resources such as multicasting. The MC does not deal directly with any of the media streams. This is left to the MP, which does the mixing, switching, and other processing of audio, video, and/or data bits.
• Gatekeepers perform crucial control and administration tasks for H.323 entities while providing network administrators the ability to incorporate management and security policies into the network. Although the H.323 recommendation describes the gatekeeper as an optional component of a functional H.323 system in practice the gatekeeper is essential. The H.323 gatekeeper is responsible for providing address translation between LAN aliases and IP addresses, call control and routing, basic telephony services such as directory services and PBX functions, H.323 traffic bandwidth usage control and total network usage control and the implementation of overall system management and security policies.
• Gateways are devices that provide the translation services between H.323 conferencing endpoints on the IP network and other ITU-compliant terminals (for example, H.320 room systems) on other circuit switched networks.

• Cisco IP/VC 3500 Series Product Family
• The Cisco IP/VC 3500 Series consists of the following products:

• IP/VC 3510 Multipoint Control Unit (MCU)
  • The MCU enables conferences between three or more endpoints. Multiple participants in multiple locations can attend the same meeting with full real-time interactivity. The MCU is designed to allow users to spontaneously initiate full multimedia, multipoint conferences, including data conferencing. It runs unattended and there is no need to schedule conferences in advance. With the MCU, a user simply dials the conference number and the MCU automatically sets up the session. Others wanting to join dial that same number and are immediately connected to the conference. Alternatively, the person initiating the conference can add users to the conference.
    Each MCU can support up to 15 simultaneous users. Its compact design also provides a way to cascade multiple MCUs together to support larger conferences. For small videoconferencing networks, the MCU features built-in gatekeeper functions. It is based upon a highly reliable RISC architecture and is simple to install.

• IP/VC 3520 and IP/VC 3525 Gateways
  • The IP/VC 3520 and the IP/VC 3525 Gateways are self-contained systems that translate between H.323 and H.320 protocols, and convert multimedia information from circuit switch (ISDN) to H.323 IP packets. They let you connect your legacy ISDN-based H.320 systems to IP-based H.323 videoconference endpoints.
    The IP/VC 3520 Gateway offers two or four BRI or V.35 WAN ports or a combination of both BRI and V.35 ports. It supports up to four calls at 128 kbps (BRI interfaces) or 384 kbps (V.35 interfaces). All ports include audio transcoders for optimal video/audio quality and bandwidth utilization. The BRI ports come standard with echo cancellation. The V.35 ports support EIA/TIA-366 signaling for call setup.

• IP/VC 3530 Video Terminal Adapter
  • The IP/VC 3530 Video Terminal Adapter (VTA) is a self-contained video interface that connects one H.320 system to an IP network. It allows companies to protect their investment in legacy technologies while implementing new IP-based multimedia communications. The IP/VC 3530 VTA connects an H.320 room-based system or small-group system to a LAN. It offers two V.35 WAN interfaces, EIA/TIA-366 signaling, a low-profile compact design, and RISC architecture to ensure reliability and easy installation.

• About the Cisco IP/VC 3520 Video Gateway
  • The Cisco IP/VC 3520 Video Gateway is a network hardware solution that allows audio, video and data conferencing to occur between H.323-compliant LAN endpoints and H.320-compliant terminals. The Cisco IP/VC 3520 Video Gateway translates H.323 and H.320 protocols so that LAN users can communicate with ISDN and PSTN users.
  • The Cisco IP/VC 3520 Video Gateway is also referred to throughout this document as the Video Gateway.

• Cisco IP/VC 3520 Video Gateway Features
• The Cisco IP/VC 3520 Video Gateway has the following features:
  • One 10/100BaseT LAN port.
  • Up to 4 BRI ports depending on the model.
  • Up to 4 V.35 DTE ports depending on the model.
  • Four audio transcoding ports supporting G.711 ´ G.723.1 and G.728 ´ G.711.
  • Supports up to 8 simultaneous voice calls.
  • Support for up to 4 simultaneous high-quality video calls (384Kbps) through the V.35 port.
  • Support for up to 4 simultaneous high-quality data calls (384Kbps) through the V.35 port.Supports direct inward dialing (DID) for routing incoming calls to H.323 endpoints without operator intervention through one of the following:
    • o Multiple Subscriber Numbering (MSN).
    • o TCS4 for H.320 video and data calls.
    • o Default Extension when an H.323 endpoint is defined as the default extension.Modifiable and replaceable internal interactive voice response (IVR) with dual tone multiple frequency (DTMF) detection of up to eight simultaneous calls for indirect inward dialing.
  • EIA/TIA-232 console port (serial port), supporting local or remote connection for monitoring, configuration and diagnostics.
  • Supports echo cancellation.
  • Front panel LED display.
  • Self test during power on.
  • No user intervention required for operation.
  • Simple configuration and setup via a Windows application.
  • Diagnostics feature.
  • Easy software upgrades from a remote site using TFTP into Flash memory.
  • T.120 support.
  • Auto detection of call bit rate (the V.35 module).
  • Internal H.323 Gatekeeper, supporting up to 100 registered H.323 endpoints.

• Cisco IP/VC 3520 Video Gateway Physical Description
• Your Cisco IP/VC 3520 Video Gateway is one of five models:
  • IPVC-3520-GW-2B
  • IPVC-3520-GW-4B
  • IPVC-3520-GW-2V
  • IPVC-3520-GW-4V
  • IPVC-3520-GW-2B-2V

   

• Cisco IP/VC 3520 Video Gateway LEDs