ViewsLetter(SM) on Provisioning

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ViewsLetter on Provisioning         3 Nov 2003        #32
     A fortnightly look at provisioning automation.

   --Linux Server Cluster handles 100,000+ IPphones,
     Points Carriers at Automated Provisioning Steps

    William A. Flanagan, Editor and Publisher

According to IBM, it has put together standard enterprise servers to create a Voice-over-IP call processor with capacity for more than 100,000 IP phones.  As experience increases, IBM expects further expandability of the same technology. 

Supporting  that many subscribers, the server shows the "carrier scale" needed to contend for the switching job in the central office.  With the capacity hurdle behind it, there are several other aspects of this project that will influence how telephone companies operate a decade from now (whatever they will be by then).

Key to the large capacity are multiprocessor and clustering features built into recent releases of Linux.  These features ensure high availability of the call processing software when running on IBM's high-end commercial servers.  This solution doesn't require expensive computers specially designed for reliability, and you can't beat the price of Linux.  

That doesn't mean free:  you can download Linux components at no charge, but assembling and integrating them is a big job.  You probably would prefer to buy a valued-added version for high availability or tailored to a complex application.  The price of the software, however calculated, will be far less than software on central office switches.

Price pressures like these are pushing makers of class 4 and class 5 central office switches away from proprietary hardware.  Their web sites indicate most have ported their call control software from their proprietary switches to standard servers. 

After considering migrations strategies for its 400,000 employees, worldwide, IBM opted to move straight to a solution based on Session Initiation Protocol (SIP).   Despite early doubts by their telecom people, who maintain 900 circuit-switched PBXs, the decision was not to take a cautious approach.  Rather than run VoIP and PBXs in a parallel, they would simply cut over groups when ready.  At the same time, they set a goal to replace the 900 PBXs with one call processor.  Considering latency for signaling packets over global distances, they determined a need for at least three sites. 

To keep the number of processors to three they need a call processor with capacity for more than 100,000 users.  They think they've found it, in Linux clusters and existing SIP proxy agent software (vendor unnamed).

The plan puts staff trained in managing voice calls at only at call processor sites.  With backups and certain legal constraints, telecom-staffed sites may number about ten, down from 900.

That means that almost all IBM locations will lack skilled telecom people.  So who's doing the moves, adds, and changes?  Not a problem, IBM believes.  The SIP protocol allows for automated registration of phones and gateways as they connect to the network.  Whoa!  That sounds like automated provisioning!

If IBM can do it internally, why can't local exchange carriers so something similar?  What about E911 location reporting, you ask? 

Done, IBM says, by DHCP and dynamic DNS, with reports from ARP about which phone is on which switch port.  Your switches not ready for that?  Panduit has an add-on panel that  front ends a switch and reports (via SNMP) the MAC address of devices on each LAN segment.  Just add a data base that matches switch ports to offices and you're done, too.

What about power?  The IEEE power standard, 802.11af, is almost final.  Several firms offer add-ons to deliver power over the LAN cable.  Enterprises also have the option of new Ethernet switches or new interface cards offered for many of the switches installed in their networks.

It will be harder for carriers to provide power for IP phones.  Analog phones draw little power from the central office, and only when in use.  Because phones are used a very small percentage of the time, Local Exchange Carriers (LECs) need to deliver only a low average power.  IP devices are computers.  They need more power, all the time--even when the phone is "on hook" so it can process incoming calls. 

As an industry, we'll solve the power problem:
--The subscriber is responsible for power under normal conditions. 
--LEC power during installation simplifies automated provisioning.  
--The question is how (and if) the LEC will provide power in emergencies to a large number of IP phones. 

Or could we find successors to the hook switch and ringing voltage so IP phones wouldn't need to be powered when idle?  I have a few ideas.  Put on your thinking cap, let me know what you come up with.  We'll compare notes in a future ViewsLetter.

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 Updated: 17 July 2004 2003

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