|Alon Cohen on:
Version 2 of H.323
By Greg Galitzine
February 6, 1998, the International Telecommunications Union met to discuss (among other
things) version 2 of the H.323 standard.
I had a chance to speak with Alone Cohen, CTO at VocalTec Communications, Ltd.,
regarding the potential impact of the ITTs decision, the differences between the new
and existing versions of H.323, and VocalTec's participation in all of this. The following
is a result of that conversation. I'd also like to thank Marty Querzoli of LNS
Communications for his help in setting up this interview for INTERNET TELEPHONY.
||How will the intended industry
impact of version 2 differ from that of version 1?
||While version 1 dealt mainly at the
LAN level, version 2 creates the playing field for the future of the IP communications
industry, establishing standards for WANs, or large intranets, right up to the full
Internet. In general, it will greatly enlarge the potential market by allowing for larger
installations on behalf of larger organizations.
||What are the main differences
between v1 and v2?
||Version 2 has a very enhanced
addressing capability based on a very enhanced set of verbs defined in its RAS v2
protocol. H.323 v2 has mechanisms to provide high availability and fault tolerant
operation, like support for backup Gatekeepers, and backup clients (end points). H.323 v2
also defines a full security framework to enable equipment vendors to support security
functions like authentication, authorization, and non-repudiation, in addition to call
privacy. H.323 v2 supports a much (7:1) faster call setup time than provided by H.323 v1.
||What was VocalTecs role in all
||Some of the above features were
initiated and driven by VocalTec. The H.323 v2 Gatekeeper basically contains elements from
our existing addressing technology called CMA. The provisioning for fault tolerant
operation, was one of the first elements that VocalTec contributed to the H.323 v2
||What is VocalTecs position
towards the new standard?
||As a company entirely dedicated to
IP telephony, VocalTec believes that the implementation of the H.323 v2 features
especially on the Gatekeeper side is essential in making IP telephony a
large-scale, successful telecommunications tool.
||What was done to improve call
||On top of the reduction of the call
setup time, H.323 v2 is capable of supporting the IETF standard for RTP redundancy, which
is a mechanism that enables the transmitter to add redundant information to help the
receiver reconstruct lost packets. This mechanism has important economical aspects because
it enables IP telephony to work on non-well-behaved but inexpensive networks like the
public Internet, and still provide good audio quality. The new H.323 v2 also supports IETF
protocols like RSVP (Resource ReSerVation Protocol) which will enable the system to
request certain guarantees from the network. This will ensure a guaranteed level of
service from an IP telephony network.
||Can IP telephony become a viable
replacement for traditional telephony?
||Certainly. With the above
capabilities and the economics of using a unified network for voice and data, and the low
price of connection, driven by the large number of IP linked devices (any PC on a
LAN/WAN/Internet), provides a very viable replacement. In addition, the extended
capability exchange and capability negotiation elements of the H.323 standard enable
existing and installed IP telephony networks and platforms to gradually be upgraded, in
order to provide much higher audio quality than available today in any phone system. The
use of an IP network as a base for future telephony enables the implementation of
easy-to-use, new and exciting services, ranging from Web-based applications to much
enhanced intelligent network services.