SIP vs. H.323

[j.eaker]

I have just started reading on VoIP and Video over IP Tech. and I was wondering if SIP could be used for a video conference set up instead of H.323. If not..then why? I think I'm missing something.

[sachon]

Technologically, there is no reason that a SIP based video conferencing network could be built. SIP makes provision for multimedia conferencing and telephony.

In practicality however, SIP can not be used for video confernecing today since no company (that I am aware of anyway) manufacturers the necessary elements of a SIP VC network - most notably endpoints, MCUs, gateways, video enabled SIP servers

[j.eaker]

do you see a manufacturer coming out with that eventually?

[albers]

Jake, It is interesting to read the comment by the guy from Cisco. SIP is an emerging protocol for a variety of applications, one of which is the potential replacement for the H.323 protocol for video over IP.

SIP (Sequential Internet Protocol) is much more straightforward in the definition of how an application uses it - H.323 on the other hand is very complex.

Who will support SIP? Everybody, eventually. H.323 based video products have hit the wall in terms of acceptability due to their complexity and the lack of solutions to address their functionality around/thru firewalls and NAT. SIP will simplify these functions in the long run.

Will SIP totally replace H.323, maybe, eventually, but there is a large installed base of H.323 endpoints, MCUs, Gatekeepers, Gateways, etc. We will live with H.323 for a long time. SIP will just help us move to the next step.

Who supports SIP today? Kind of funny that the Cisco guy said no one - that is because they sell Radvision manufactured video products, and Radvision is the H.323 kings - they own and license most of the H.323 protocol stacks used in other people's products.

SIP is supported with the new version of Windows, Windows XP. Therefore, NetMeeting on XP will be either a SIP client or an H.323 client.

MCUs? MCUs are essential for true video conferencing for enterprises, you have to have multi-point conferences. CUSeeMe Networks, recently merged with First Virtual Communications, has a software-based MCU product called Conferencing Manager, and a full blown video suite called Videoware. the MCU in both products supports SIP today! It has been fully tested with the Microsoft Windows XP SIP client. So, H.323 clients and SIP clients can join a multi-point conference.

Next step, another protocol stack in gateways, to support h.323 to SIP to h.320 to h.321.

Another next step, the use of mpeg4 algorithms rather than G.261 and G.263 for higher resolution video. SIP as the transport...

12 to 18 months, SIP enabled products will be available for all parts of the video networking solution.

Hope this helps.

[rtomlin]

RFC 2543 might help clarify some of this