<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Verdana; font-size: 10pt; color: #000000'>http://www.cisco.com/en/US/docs/ios/solutions_docs/voip_solutions/TA_ISD.pdf<span><br><br><span name="x"></span>---<br>Lelio Fulgenzi, B.A.<br>Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1<br>(519) 824-4120 x56354 (519) 767-1060 FAX (ANNU)<br>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^<br>Cooking with unix is easy. You just sed it and forget it. <br> - LFJ (with apologies to Mr. Popeil)<br><span name="x"></span><br></span><br><hr id="zwchr"><b>From: </b>"gr11" <grccie@gmail.com><br><b>To: </b>"Lelio Fulgenzi" <lelio@uoguelph.ca><br><b>Cc: </b>cisco-voip@puck.nether.net<br><b>Sent: </b>Tuesday, November 22, 2011 9:58:15 PM<br><b>Subject: </b>Re: [cisco-voip] Voice Gateway router size<br><br>Thanks Lelio and all.<br><br>Yeah i meant to say ISR G2 sizes. I will try finding and using the Erlang calculator. Does anyone has the link from Cisco, Lelio is referring to.<br><br>Thanks<br><br><div class="gmail_quote">
On Wed, Nov 23, 2011 at 10:53 AM, Lelio Fulgenzi <span dir="ltr"><<a href="mailto:lelio@uoguelph.ca" target="_blank">lelio@uoguelph.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
The key value you need here is utilization. The number of people or phones at a site isn't the best number to use since it may not reflect how much they use off-net resources. If you have access to records off the current PBX, this will give you a better idea. Once you have these numbers, you can use Erlang calculations to let you know how many PRIs (and if billed separately, how many active channels) you will need. Someone recently posted a link to a Cisco doc that summarizes things very well. It was that document that I used recently to give me a clue to our utilization.<br>
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The DSP calculator will tell you the DSP resources you need. (<a href="http://www.cisco.com/go/tools" target="_blank">www.cisco.com/go/tools</a>)<br>
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As far as the routers are concerned, you should be looking at 2900/3900s at the minimum. 2800/3800 are end of life.<br>
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Each model has it's advantages, but mainly it will be max calls, SRST capacity and expandability. Picking from one model to the next is hard because if the small incremental costs between them most of the time. Stick to what you need for the next two or three years and you should be fine. We really like to have redundant power supplies because of electrical maintenance that goes on and the fact that you can feed them from separate circuits/UPS units.<br>
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There are docs on Cisco that will compare the router units.<br>
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Sent from my iPhone<br>
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On Nov 22, 2011, at 6:25 PM, gr11 <<a href="mailto:grccie@gmail.com" target="_blank">grccie@gmail.com</a>> wrote:<br>
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> Hi all,<br>
><br>
> can you guys advise what approach normally you follow while calculating the below requirements:<br>
><br>
> 1) Router size - 2801/2811/2821/3845 - any best practice<br>
> 2) ISDN Channel calculation - Ratio of Users to ISDN channels calculation<br>
> 3) DSP Resource calculation<br>
><br>
> I have few sites (with size varying from 50 upto 1000 users) lined up for migration from PABX to VoIP. Was calculating the requirements, thought it would be good to have second opinion.<br>
><br>
> CUCM is running on 8 and all gateways will be MGCP.<br>
><br>
> If anyone can please share the best practices or their experiences.<br>
><br>
> gr<br>
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