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List:       voipsec
Subject:    Re: [VOIPSEC] Voipsec Digest, Vol 8, Issue 7
From:       Bill Flanagan <bill () flanagan-consulting ! com>
Date:       2005-08-30 14:47:33
Message-ID: 43147185.2020806 () flanagan-consulting ! com
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Well said, Geoff.

My clients seldom understand how much VoIP differs fundamentally from the 
traditional TDM PBX.  When contemplating VoIP on an existing data network, I 
usually need to point out the upgrades that will be needed to even approach the 
level of availability afforded by the cheapest key system or or miniPBX.

One of the most difficult aspects is getting router managers and engineers to 
count "scheduled maintenance" as an outage when it affects service.  They would 
never accept such outages on their home phones--too risky in case of an 
emergency.  Worse, it's not that they don't want the same availability for VoIP 
in the office, it's that they don't seem to connect that concept with taking 
routers and Ethernet switches out of service.

When was the last time you sent an email to the help desk because your phone was 
out?

Bill

> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Tue, 9 Aug 2005 08:49:43 -0400
> From: "Geoff Devine" <gdevine@cedarpointcom.com>
> Subject: [VOIPSEC] RE: TLS as the SIP security mechanism
> To: <Voipsec@voipsa.org>
> Message-ID:
> 	<9CDE330E7358724EA30D93598D24DE4A010E5D@exchange.cedarpointcom.com>
> Content-Type: text/plain;	charset="iso-8859-1"
> 
> I think you fail to grasp the requirements of primary line telephony.  The \
> telephone network has been designed to avoid outages since it's good public policy \
> to have telephone service available... even when the power goes out.  In my voice \
> over cable space, residential VoIP devices have battery backup.  The network has \
> battery backup and diesel generators.  Everything is engineered so the core \
> maintains five 9's up time.  This is required so when someone needs telephone \
> service in an emergency, they'll get dialtone.   
> The telephone network is, of course, imperfect and doesn't achieve true five 9's at \
> the core.  If the intent hadn't been to engineer a five 9's system, it would \
> certainly be an order of magnitude less stable than it is.  If you design a network \
> where you have restart avalanches after every bounce of a SIP proxy, you can't \
> possibly achieve these objectives.  You have a moral and ethical obligation to \
> engineer them out. 
> You ask why anyone would want to have hundreds of thousands of subscribers on a \
> proxy?  In my voice over cable space, you'd be laughed out the door if you didn't \
> have a scaling story that looked like that with product that can do 100K today.  \
> Nobody wants to manage a wall of equipment racks full of machines to service a \
> city.  The operators don't have the space in the head end for all the equipment.  \
> Problems like restart avalanches certainly go away if you can limit a SIP proxy to \
> 1000 subscribers but you wouldn't sell any in my space. 
> Geoff
> 
> ________________________________
> 
-- 
____________________________________________
William Flanagan        Ph:  +1.703.242.8381
Flanagan Consulting     Fx:  +1.703.242.8391
45472 Holiday Dr. #3, Sterling, VA 20166 USA
www.flanagan-consulting.com

"Beware of false knowledge; it is more dangerous than ignorance."
                                         --George Bernard Shaw


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