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28

The HP ProCurve 1810-8G Switch (J9449A) is an 8-port Gigabit switch that can be powered by an upstream PoE switch. I use it in environments where I can't accommodate a power brick or need to control power from a central location (e.g. a UPS in a central server room). They're also nice when you need to use small switches because of a lack of ethernet drops in ...


8

If the PoE switch is 802.3af compliant (most are, but there are other implementations out there. I believe Cisco has their own) then it's safe to enable PoE on every port. Basically, the PoE switch will check for a certain resistance between two of the pairs of wires on the other end of the device. If the resistance is within a certain tolerance, the device ...


8

I don't know about the standards changing for PoE, haven't heard of any issues there. We run many Cisco VOIP phones and while we do have some issues (the phones are basically computers; they do lock up and resetting them is a matter of unplugging and plugging them back in) we haven't have direct issues due to PoE. If you don't have PoE switches you have to ...


6

Nothing from hard experience, but I would take it as a given that PoE switches draw more current than their regular cousins. Cisco has some numbers for Catalyst 65xx series equipment. To summarize a 48-port 10/100/1000 board dissipates 443 BTU/Hr and the PoE version of that board puts out 518 BTU/Hr (+17%). To be safe I'd inflate the heat load by ...


6

As long as it's reversed on BOTH ends then I can't imagine it would matter at all. Of course, if someone one-day re-terminates one end correctly then you're likely to have issues. Depending on which pair it is (you didn't mention), for 100BASE there's a 50% chance that it won't matter since only 2 pairs are used; 1+2 (Orange) and 3+6 (Green). For the sake ...


5

There are two Power-over-Ethernet standards; IEEE 802.3af-2003 (PoE) which supports 12.95-15.4w (depending on the length/attenuation of the cable) IEEE 802.3at-2009 (PoE+) which supports up to 25.5w (again depending on the cable). So you need to understand what the cameras requirements are and then look at both switches but ensure it'll work but certainly ...


5

No. POE will only be supplied to devices that are directly connected to the POE switch, and only by request. The standard by which this works is described here: http://en.wikipedia.org/wiki/Power_over_Ethernet#Standard_implementation


4

You can get multiport PoE injectors, e.g. this one: http://www.midspans.com/pages/15w/POE370U_15.4W_8-16-24-port_midspan.php (no idea if it's good or bad, first one I found with 16 ports).


4

The PoE switch, if it's 802.3af compatible, will not send power to the device (in any amount worth mentioning) until it requests power. A PoE Injector should either not connect the powered pins to the upstream port, only the downstream port. This would be for 100Mb devices only as 1Gb requires all 4 pairs. For 1Gb devices the PoE injector must protect ...


4

PoE is negotiated between the devices on each end of the link, so there is no danger of the switch supplying power to a device that doesn't request it. http://en.wikipedia.org/wiki/Power_over_Ethernet#Powering_devices


4

I doubt you will find such a product. Instead, I would look for a generic PoE injector/extractor. I think this is one of those products, but I can't get the website to load. http://www.dlink.com/products/?pid=332


4

The PSE (Power Sourcing Equipment) and PD (Powered Device) negotiate to see if the end device is compatible of being powered and at what standard. So plugging in a non PoE device will not damage said device. Here is a good read about the basics of PoE


3

There are 2 standard forms of PoE (there are other forms... but they've never been standardized) ... depending on the kind of PoE required for your device... you may not be using the right flavor. Active PoE (which is what most switches that support PoE does... ) requires some extra hardware on the device which will apply a small amount of resistance ...


3

The Powered Device should recognize it has "local power" and not request PoE power. This assumes that you're talking about 802.3af compliant devices (sometimes called "active" devices) and not "passive" power injectors and their associated devices (they just throw voltage "out there" without regard for necessity, destination, or compatibility). What you ...


3

Yes. You can run 100-megabit PoE devices on a Gigabit PoE-enabled switch.


3

You didn't specify your troubleshooting steps, but we'll have to assume that you plugged the server into another switch to test it. The more plausible cause might be static build up during the cable change. The switch is delivering. Max of 15.4 volts, on the pins that are not used for networking.


3

PoE checks for a resistance between two wires, and if it is within a certain tolerance, it sends power down that port. A faulty network adapter can, in some scenarios, cause the switch to believe the other device is PoE compatible, when it is in fact not (because for whatever reason, it happens to have the right resistance between two wires). We have a ...


3

I'd recommend a low-cost PoE switch or possibly purchasing a higher-end PoE switch/blade along with your switch refresh. The phones will be on their own network/vlan, correct? It may make sense to segregate them and provide a dedicated device (24 or 48 ports).


3

Yes there are extra cooling requirements. POE uses more current, current equals heat - so yes you need more cooling (and power of course, in fact choosing the best PSUs for POE-equipped Cisco Cat 65xx's can be more than a 2 minute decision). As for how much more cooling, well I always say hope for the best but plan for the worst, look at how much power you ...


3

We're facing this exact problem as we're deploying POE switches into our edge in preparation for an eventual VOIP project. We don't know what brand of VOIP we're going with, we just know that in the lifetime of these edge switches we'll need to support POE. In the process we had to upgrade the power outlets in many closets as the POE switches need something ...


3

if the reverse is on both ends then there is no problem. for 100BASE and less, reversing pair polarity on one end will probably not work. however, I have seen chipsets that are tolerant of these wiring errors. I think this has become more common since the introduction of Gigabit Ethernet. for 1000BASE and 10 gig, pair polarity doesn't matter. some ...


3

To add to what's been said for data, it won't matter at all for POE since the voltage is applied across the pairs, not within them (1-2 and 3-6 for Alternative A, 3-4 and 7-8 for Alternative B).


2

plugging in a non-PoE switch in front of a PoE switch will mean that all devices under the non-PoE will not have power That ^^ would be correct. PoE switches in the enterprise are really becoming the norm now, especially edge switches. The cost differences are pretty minimal at least with the big players like Cisco, HP, Extreme, etc. WAPs, VOIP ...


2

Not going to happen. Keep the current setup with the injector or try a switch that can provide more PoE wattage (PoE+) to individual ports.


2

I talked to Cisco support today and they knew the answer right away - Green Ethernet causes problems, and this is turned on by default. The guy said that this happens mostly with Macs. Well, I now know that it happens with the XS35V2's built-in JMicron PCI Express Ethernet Adapter. Once I turned 802.3 Energy Efficient Ethernet off on this port, it started ...


2

The 802.3af and 802.3at standards both specifiy 48 V (actually 44V - 57V for 802.3af and 50V-57V for 802.3at at the PSE side) as the only operational voltage. You always could use your own voltages if you have something proprietary (i.e. provide your own power injector / splitter pair), but if you need standards interoperability, you would need to stick with ...


2

Yes. This would likely work. Are you sure the NVR provides PoE? Will there be a separate PoE switch? Either way, the distances work out and should be fine. Easy to test this, right?


1

If I am reading your question right, you have an edge switch that is both POE-PD (powered device) and is also a POE-PSE (power sourcing equipment). I assume this switch is hooked up to a larger distribution switch which is capable of generating enough power per port to supply the combination of the edge switch and some combination of endpoints like IP ...


1

The PoE spec says that a device that can accept both PoE and power from another source must isolate the power sources so as not to send power back through the Ethernet connector. So if you're using reputable stuff, then your network gear should be OK. That being said, the spec do not address what the device should do when it has power via PoE and another ...


1

There is an update that fix this. https://supportforums.cisco.com/docs/DOC-18337



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