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Re: Video Conferencing: Products, and Issues with Network Bandwidth and Security

  • From: Marshall Eubanks
  • Date: Fri Feb 08 14:29:37 2008


There are some things you need to think through. (I am CTO at Iformata Communications, and this
is our core competency.)

- Point to point only, or multipoint ? Multipoint will mean MCU's.
- Webcams or professional gear (like Polycom HDX 8000 HD video) or telepresence ? (Over
an order of magnitude of cost increase between each step.)
- Bandwidth ? - from under 384 Kbps to over 20 Mbps at each endpoint.
- and, of course, the budget, which is tightly coupled to all of the above.

Also, are any sites ISDN only ?

On Feb 8, 2008, at 1:04 PM, Jon R. Kibler wrote:

Hi All,

I have a client that wants to implement video conferencing.
They would like to have multiple video participants and
collaborative whiteboards.

Anyone have any experience with such products? Comments
and/or recommendations on products?

More to the point of this post... what are the network
and security issues associated with VC? For example:

-- Would it be reasonable to expect that a remote user
   on a DSL connection to be able to VPN into a WAN
   and participate?

Why not, if the symmetric bandwidth is (truly) there ? You may need some QOS if the DSL has other
uses (like, say, it's in someone's home).

-- Are most of the products multicast? If so, what are
   the security issues with multicast and will it work
   through, for example, a Cisco VPN client tunnel?

Basically, none of them are, except for some academic products like VRVS or the Access Grid conferencing system.

-- What are the typical network bandwidth requirements?
   Are they per participant based or some other basis?

Generally, it is static for each participant, for a given video quality.

(Typically, if one full screen is 1 Mbps at a given quality, then it can do a
1 Mbps point to point call, a 512 Kbps half screen 3 point call, a 250 Kbps quarter screen 5 point call, etc.)

So the outbound bandwidth may decrease, but the inbound bandwidth is roughly constant for
any number of end-points and a given quality. (You can also mix and match,
1/2 screen for one site and 1/4 screens for two,
for example, but it doesn't change this principle).

Note that all of this multi-point stuff has to go through an MCU and MCU bandwidth frequently
requires more thought than endpoint bandwidth. (If you have a simple star topology, then the MCU may need
N x the endpoint bandwidth. YMMV.)

-- What are the general security issues with VC? Can it
   be run through an IPSec tunnel or does that break it?

You can do IPSEC or you can do application layer encryption or even both.

Note that firewall / NAT traversal is also frequently an issue. Polycom sells
gear for this and it also frequently requires some thought.

Any ideas for good sources of information? Google doesn't
seem to provide me with much usable information when
trying to answer these types of questions.

Hope this is useful. If you are coming to Apricot I would be glad to talk, as I intend to
present on just this topic, for Telepresence.


THANKS! Jon K. -- Jon R. Kibler Chief Technical Officer Advanced Systems Engineering Technology, Inc. Charleston, SC USA o: 843-849-8214 m: 843-224-2494

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