Protocol Convergence - 8 : H.323
Full playlist of #Protocol #Convergence identifies existing and emerging protocols that support converged communications. Covers Ethernet, #DHCP, IP, SIP, H.323, #Megaco, and more.
• 52 : Protocol Convergence - Fundament...
The H.323 standard started as a specification for videoconferencing. However, as VoIP and IP telephony convergence started to grow, more and more information was added to the specification. H.323 was growing too large to be a single protocol. So now, H.323 has evolved into a specification that is actually an umbrella standard for many other specifications. This means many of the specifications that were at one time part of H.323 have been given their own identifier, and are now separate sub-standards.
Essentially, the H.323 standards are designed to allow IP networks and the circuit-based legacy telephone networks to coexist. What H.323 does is supply the protocols and hardware specifications to allow mixed communication environments to work.
The H.323 standards govern 4 types of communication devices.
First is the terminal. The terminal is the end point of the network. Terminals can be IP phones or computers with integrated phone systems. These computers with built-in phone capabilities are called soft phones, because they are actually software phones.
The next type of H.323 device is the gateway. We have talked about gateways before, and as you should remember, their job is to act as an interpreter to translate communication between legacy switched telephone networks and IP-based networks.
Next we have the gatekeeper. The gatekeeper's job is to keep track of the terminals and gateways, define policies for bandwidth, support the re-routing of calls, and to support mappings of addresses to names.
Finally, H.323 defines the Multi-Point Control Unit, or MCU. This device is responsible for supporting conference calls. When more than two users are connected to one call, there must be some function available to split and/or multicast the call. This is what the MCU does.
All the H.323 functions can be installed on separate devices, or multiple functions can be integrated into a single device.