Fair enough, I guess I was concentrating on this line in Jerry's message :) > The only reason I can think of not to is to eliminate the cost of the second > cable.
I believe you're mistaken about the QOS though. > QoS is not required on lightly loaded links and will do nothing for you on > over loaded ones. QOS will absolutely allow voice traffic to pass with priority over heavily loaded links -- this is in fact the reason that it would be implemented. Obviously giving priority to the voice traffic on these heavily loaded links serves to mitigate both latency and jitter. > The concern is almost never one of taking bandwidth away from the desktop, > but one of the desktop taking bandwidth > (especially by introducing latency) away from the phone. Agreed -- but with VLAN tagging and QOS, the issue of how much bandwidth the desktop uses and/or needs becomes moot since the phone is given priority. Dave David Gibbons wrote: > Two separate networks? Did I miss something? I feel like I'm taking crazy > pills! Two separate physical networks means twice the hassle, twice the > maintenance, twice the cost, twice the headache. Not to mention the fact that > the whole idea of VOIP is to simplify IT and focus on converging data and > voice networks. > > This is what VLANs and QOS do best. I dare say it's what they were designed > foe. I can't think of any reason that I would ever recommend two ports per > desk to support telephony -- ever. It's ludicrous to think that two ports > will be better than one if we're setting up our VLANs and QOS properly. A > phone takes very, very little bandwidth away from the desktop and a decent > one will support tagging its frames for the alternate voice VLAN. > > --snip-- > In almost all cases it is much better to have two seperate networks. > This may be impractical in some smaller installs, but in any office > setting we always do this. The only reason I can think of not to is to > eliminate the cost of the second cable. > --snip-- > That's two _logically_ separate networks. The key point is that the "last yard" cable to the phone is not shared with the computer. The issue is not a lack of bandwidth but that the phone has to try and get its little packets inserted between the massive packets of a database lookup or file transfer in a timely manner (latency and jitter). You might get away with a single logical network on a smaller site or a larger one with very light traffic. QoS is not required on lightly loaded links and will do nothing for you on over loaded ones. I only use it on WAN links where bandwidth is more expensive. regards, Drew -- Drew Gibson Systems Administrator OANDA Corporation www.oanda.com _______________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users _______________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users