[Asterisk-biz] Forklift a 2000 phone PBX

[steve szmidt]

On Sunday 27 March 2005 15:14, Reid Forrest wrote:
> > This seems like a really bad idea. Why lock down into a not only old and
> > outdated technology, but for 2000 users?!!
> >
> > You want to keep the network operating efficiently. Modern switches does
> > a lot
> > better job than yesterdays technology. If you have 250 people on the
> > phone at
> > the same time, and you are using g.729, you have used 10Mb right there.
> > Never
> > mind any other protocol.
>
> Steve, I agree with you that trying to run voice over Cat3 is not the best
> idea. But, I think your math may be off in the calculation above. 250
> people on the phone using g.729, even compensating for protocol overhead of
> 25% is only 2.5Mbit/sec. 

Sorry but we are not talking about a one way conversation. It requires shy of 
20K for a two way conversation.

> In addition, you are assuming that the voice 
> network is completely FLAT, not switched. A fully switched voice network
> would reduce bandwidth consumption at every station. 

No it doesn't. Switched does not lower the needs of a g.729 connection. The 
only savings are in not having collisions, and retransmissions, as with a 
hub. 

> A 2000 user switched 
> voice network over Cat3 is viable, as long as you keep data off of it.

Well, it turned out that he has Cat 3 from the previous phone system 
available, and that is what he is talking about. I missed that point.

As for a dedicated Cat 3 to run a voice leg to a switch that would obviously 
be fully workable. However, if you were to integrate it to a 100Mb network 
then it will switch down the 100 for each 10 packet entering that leg. Of 
course that might still be faster than running a 10Mb network.

-- 

Steve Szmidt

"They that would give up essential liberty for temporary safety 
deserve neither liberty nor safety."
                                Benjamin Franklin