A little off topic but.... I need to put a 24 port Gig PoE switch into a small office - no computer room / rack etc. All CAT5 terminates near the owners desk (smart huh?). I want to put a PoE switch in place, with 24 ports and Gig speed. Everyone I've researched so far is LOUD... Anyone know of a quiet one? Thanks -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20090131/af546930/attachment.htm
Hello,> I need to put a 24 port Gig PoE switch into a small office ? no computer > room / rack etc. All CAT5 terminates near the owners desk (smart huh?).I had a similar problem some days ago. 24-port GBit Switch in the middle of a classroom... I ended up with a kind of "semi-loud" setup: I bought a 3Com 3CBLSG switch (this is without PoE, but there is a PoE version of it). There are two quite noisy 40x40x10 fans inside. I replaced the two with one 40x40x20 ebmPapst silent fan (model 412/2, 18dB), left the other fan offline and mounted the whole thing vertically so that convection supports the remaining fan. I tried with two silent fans (enough space inside), but this still was too noisy. Some measurement indicates the cooling is sufficient this way. But understand that I've no long term data, as I installed this setup just two weeks ago. And of course your warranty is void ;-) Greets, Claus -- CHECON EDV-Consulting und Redaktion Claus Herwig * Barer Stra?e 70 * 80799 M?nchen +49 89 27826981 * Fax 27826982 * c.herwig at checon.de
OCG Technical Support wrote:> A little off topic but.... > > > > I need to put a 24 port Gig PoE switch into a small office ? no computer > room / rack etc. All CAT5 terminates near the owners desk (smart huh?). > > > > I want to put a PoE switch in place, with 24 ports and Gig speed. > Everyone I?ve researched so far is LOUD...Chances of finding a PoE switch that is quiet out of the box is about as good as finding a government 'worker'. It's kind of an oxymoron. Of the switches I've used, the Linksys/Cisco line was the loudest. Dlink's were quieter, but still not something you'd want sitting next to a desk. About the only fanless PoE switches I've seen are the smaller Netgear's, but they are not Gigabit. Darrick
2009/1/31 OCG Technical Support <support at ocg.ca>> A little off topic but.... > > > > I need to put a 24 port Gig PoE switch into a small office ? no computer > room / rack etc. All CAT5 terminates near the owners desk (smart huh?). > > > > I want to put a PoE switch in place, with 24 ports and Gig speed. Everyone > I've researched so far is LOUD... > > > > Anyone know of a quiet one? > > > > Thanks > > > > _______________________________________________ > -- 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 >I can't remember the exact model but I used a Cisco catalyst switch for a class and after reboot, it was very quiet. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20090201/467d8795/attachment.htm
> How are you getting these 80 or 120mm fans in a 1U chassis? Remember you > got barely 45mm to play > with at the back and front of the switch. How are you going to mount a > 80mm or 120mm fan on there? Are you assuming that the units mounted > above (or below) your switch is a short 1U? You can't assume that... > >I guess one shouldn't assume as a rule, but... If I were concerned about noise, it would be because I am positioning this near people, and not in a densely-packed rack. Thus I would be OK eliminating the 1U constraint. I think these tend to be distinct deployment scenarios. And thinking about that, do PoE switches tend to be deployed near people? You tell me. I'd like to find a quiet 24-port PoE switch - even at 100 Mb. -------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/x-pkcs7-signature Size: 3234 bytes Desc: S/MIME Cryptographic Signature Url : http://lists.digium.com/pipermail/asterisk-users/attachments/20090202/3614acad/attachment.bin
"Wilton Helm" <whelm at compuserve.com> wrote:>>A modern switched mode PSU ought to be more than 90% efficient,>In theory, yes, in practice, not likely. It is harder to get high >efficiency from an isolated supply than a non-isolated one. I get ads >from IC manufacturers all the time about there 90 to 95% efficient >solutions, but these are boost or buck regulators--non-isolated. State >of the art in commercial practice for isolated supplies is around 80 to >85%, and typical commercial practice is more like 70 to 80%.The per-port regulators would be non-isolated. Probably feeding off an internal 48V bus.>Now you >have more like 60 watts of heat radiating from this power supply. Go >stick a 60 watt light bulb (incandescent) in a small metal box and see >how easy it is to keep cool.Well, the bulb has a peak permissible operation temperature of about 160 degrees C ... so likely no extra cooling required. :-) -- /"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia \ / ASCII ribbon campaign | Religion is regarded by the common people X against HTML mail | as true, by the wise as false, and by the / \ and postings | rulers as useful. -- Seneca the Younger
>The per-port regulators would be non-isolated. Probably feeding off >an internal 48V bus.Yes, so that will be 90 to 95% efficient, but it is fed from an isolated supply that at best will be 90%, probably less. Those numbers must be multiplied, giving 81 to 86% overall efficiency--and I am assuming best in class, which only a switch at a high price point would offer.>Well, the bulb has a peak permissible operation temperature of about >160 degrees C ... so likely no extra cooling requiredTrue in open air. However, inside a metal enclosure as I described to make it applicable to the situation, the enclosure would probably get warm enough to be a fire hazard. The light bulb might still be fine after the building burned down! :-) I've designed products and put them through UL, CSA and CE safety testing.>It'd still be a 400W PSU if it supplies 400WYou can play various games with the numbers, such as choosing input versus output power to write in the spec. The label will have to indicate 500 W of power consumed, by law. No matter how one plays with the numbers, an 80% efficient supply that delivers 360 watts will consume 450 W, and turn 90 W into heat. If it is rated for 400 W output, it is probably in a portion of its range at 360 W where it is achieving near optimal efficiency and the above math would apply. In cases where half the loads drew less power and/or were not POE loads, the consumption would go down, and so would the heat. However the manufacturer can't design for that case and if they don't provide automatic fan control (which apparently most switches don't have), the fan must be designed for worst case, which in the above example is 100 W of heat. Also, at 25 to 50 % load, the efficiency will probably be lower because it was optimized for a larger load, and because some losses are fixed (not load dependent).>This whole thread is getting stupidIf some increase in understanding occurs, then it isn't a waste. No it won't change the behavior of any switches, but it might help people understand why. Wilton -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20090203/5eff1596/attachment.htm