<div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>Date: Tue, 7 Mar 2006 18:26:12 -0500<br>From: "Jason Adams" <<a href="mailto:jadams@sumosystems.net">
jadams@sumosystems.net</a>><br>Subject: [Asterisk-Users] System Design<br>To: "Asterisk Users Mailing List - Non-Commercial Discussion"<br> <<a href="mailto:asterisk-users@lists.digium.com">asterisk-users@lists.digium.com
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<br><br>Hey Everyone,<br><br>We are in the works of planning a new * installation for our company.<br>We have 20 users in our main office and 5 users in a remote office a<br>couple of states away. Our call volume for the main office will be
<br>anywhere from 5-10 concurrent calls. The remote office will have about<br>3 heavy users with two users making calls occasionally.<br><br>Right now we have an existing PBX. We have a T-1/PRI coming into the<br>main office and a DSL connection at the remote office. We have a Cisco
<br>2610/PIX 501 at the main office a cheesy linksys router at the remote<br>site.<br><br>We are planning on purchasing new Cisco IP phones for everyone.<br><br>My main question is this: What type of hardware/network design would be
<br>best for this situation? Would a full T-1 at the remote site work with<br>a VPN between the offices? Or would a higher bandwidth DSL work with a<br>VPN? Or should we move to a Point-to-Point connection? What type of
<br>hardware would be best for the end-to-end communication in regards to<br>QoS? I know the PIX 501 doesn't support it.<br>Would it be best to have two * servers in each office or for that call<br>volume at the remote office does it make sense? I was thinking of a
<br>Dell Power Edge server with 4GB of ram and a dual processor.. is that<br>enough?<br><br>Sorry for all the questions!<br><br><br> - Jason<br><br>-------------- next part --------------<br></blockquote></div><br>Jason-<br>
<br>You're right, that's a lot of questions. Let me try to net it out a little for you.<br><br>First off, it sounds as if you're using the Internet to connect the two offices. Understand- nothing presently there will provide QOS over the Internet- from that perspective, your existing equipment is just fine. If you're considering making changes, and budget is not an issue, a private WAN setup- Frame Relay, for instance, that provides low latency between the two points, is what you're looking for, as you can perform QOS on it. Speedwise, however, depending on the level of compression you go with, at 5 simultaneous calls (my assumed maximum with 5 remote users- YMMV), you really dont need anything faster than a 256K connection between the two points- assuming the latency can be kept in the 60ms range or less. DSL, specificall aDSL is notoriously awful for high-bandwidth VoIP applications, as it's asymetric (faster download than upload in general), and the speed will vary at random based on the carrier and time of day. If you compress, you can get away with 128K for the voice portion of the link (Remember, that's 256K for the Voice side, not counting whatever other traffic is going on at the time)- and if you trunk IAX, you can potentially get even smaller. The big question is- at 20 users and 5 users- how many calls are going on across the VoIP link?
<br><br>Secondly, consider your PSTN connections. Are you using a PRI at the main office, and some POTS lines at the remote? Do you need to use a VoIP provider for all of it? Want to get rid of those POTs lines and use the PRI for the remote office as well? All of which will change the equations as far as how much bandwidth and what kind of hardware you need in each office.
<br><br>Finally, hardware. That dual CPU machine is a cadillac for 20 users- even 25 users. I won't go in to my opinion of Dell, that's a theological discussion- but I'd sandbox that setup on something far smaller- a 1Ghz Celeron should be more than up to the task for Asterisk, depending on what else you're doing at the time, even with transcoding going on. I personally would recommend two low cost servers- look in to astlinux and a Soekris box for the remote office (might be pushing it, but again, it depends on your apps and transcode requirements), and a cheap commodity machine for the main branch- it should be just fine for what you're looking to do. Trunk the two machines together, and you've got all the power in the world- Dundi or IAX switched dialplans will take care of most of the headache for you.
<br><br>If you want to dig deeper into details, I'd be happy to offlist- I'm posting this here as more of a general selection/architecture guide.<br><br>-Paul Davidson<br> PlanCommunications, LLC<br>