Table of Contents
Introduction
This chapter provides a general overview of the Cisco IP/VC 3500 series product and architecture and describes the physical features and functionality of the Video Terminal Adapter (VTA) product.
Videoconferencing is helping organizations make the transition to an Internet-driven world with instant worldwide connectivity. Spurred by changes in communications technology, low-cost bandwidth, plus continuous improvements in hardware and performance, videoconferencing solutions provide large and small enterprises, government institutions, and educational environments with the tools they need to be more productive, to make decisions faster, to train and educate more effectively, and to save time and avoid the burden of travel.
The Cisco IP/VC 3500 Series product family is Cisco's videoconferencing solution. It is comprises several products that are developed for enterprises and service providers who want a reliable and easy to manage network infrastructure for videoconferencing applications deployment. Cisco videoconferencing products enable video applications over IP networks, and integrate legacy H.320 system, thus protecting enterprises' original investment in videoconferencing.
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.
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.
- Terminals, gateways and multipoint controller units are also known as H.323 endpoints. The collection of all terminals, gateways, and MCUs managed by a single gatekeeper comprise an H.323 Zone.
The Cisco IP/V 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 (MC), 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.
- 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.
Note EIA/TIA-232 and EIA/TIA-366 were known as recommended standards RS-232 and RS-366 before their acceptance as standards by the Electronics Industries Association (EIA) and Telecommunications Industry Association (TIA).
- The IP/VC 3525 Gateway offers a single PRI interface to the ISDN network. It supports T1 and E1 connections, making it suitable for deployment anywhere in the world. The IP/VC 3525 Gateway supports three calls at 384 kbps, four calls on E1, or up to eight calls at 128 kbps. Audio transcoding is also supported as a standard feature for optimal audio quality.
- Like the IP/VC 3510 MCU, the IP/VC Gateways offer built-in gatekeeper functions for small videoconferencing networks, a compact design and reliable RISC architecture.
- 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.
The VTA is a self-contained terminal adapter that translates between H.320 and H.323 communications protocols. The VTA connects your H.320 video conferencing system (room system or group system) to an IP network (LAN, Internet, or intranet) and provides complete end-to-end interoperability between the room system and all other H.323 devices on the network. By opening up your room system to the previously inaccessible world of H.323 networking without losing any H.320 functionality, the VTA protects and enhances your room system investment.
VTA features include the following:
- Interoperates with gateways.
- An EIA/TIA-232 modem connection port for remote diagnostics.
- Dialing signals (for incoming calls) and address translation.
- Session speeds up to 384 kbps.
- One IEEE 802.3 LAN (Ethernet) UTP connection.
- Dual V.35 DCE interface with EIA/TIA-366.
- Far End Camera Control (FECC) support.
- SNMP-based configuration program.
- Front panel LED display.
- Dialing profiles to set bandwidth utilization.
- Audio: G.711, G.728 (transparent support).
- Video: H.261 CIF and QCIF.
The VTA is built in a low-profile unit designed to comfortably fit in the cabinet of your H.320 video conferencing system or in a 19-inch rack.
The VTA front panel contains LEDs and an asynchronous EIA/TIA-232 serial port that you can connect to a PC or a modem. Use this port to run a terminal session for defining IP addresses or running diagnostics.
Figure 1-1: VTA Front Panel
Table 1-1 indicates front panel LEDs device status and LAN and WAN activity.
Table 1-1: Front Panel Activity
| LED
| Color
| Indicates
|
PWR
| Green
| Power is switched on.
|
TEST
| Red
| VTA is powering up or is being configured. This turns off after the VTA successfully powers up.
|
WAN
| ---
| ---
|
SESSION (1)
| Green
| Indicates video conferencing activity
|
SESSION (2)
| Green
| Indicates video conferencing activity for two-channel (2B) calls only.
|
LAN
| ---
| ---
|
LINK
| Green
| LAN link is present; port is connected to the network.
|
SESSION
| Green
| Indicates video conferencing activity on the LAN.
|
For information on using the LEDs for problem solving, see the "LED Indications" section in the "Tips and Troubleshooting" chapter.
You can connect the EIA/TIA-232 console (serial) port directly to a terminal or to a remote terminal via a modem for diagnostics, monitoring, and configuration. The console port has a female DB9 connector. For information on connecting this port, see the "Cable Connectors and Pinouts" appendix.
The VTA rear panel contains one LAN port, two serial ports (to connect the VTA to the room station), and a power plug and switch.
Figure 1-2: VTA Rear Panel
This is a 10BASE-T IEEE 802.3 Ethernet connection (RJ-45 socket) tjat supports 10 mbps bandwidth.
Each of the two high-speed 26-pin serial ports (female) connects to a V.35/EIA/TIA-366 Y-cable, which connects to a corresponding cable on the room system. Use port 2 only when running 2B calls.
The VTA automatically adjusts to the supply voltage ranging from 100 to 240V AC,
50/60 Hz.
Posted: Fri Nov 12 19:46:23 PST 1999
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