How to make IEEE802.3af PoE compliant

We are going to move to smaller office.   When we move, we want to improve our network cabling and implement new technology.
Current office
1)  Cat3 & Cat5 mixed wiring
2)  Switches are all over.  Hard to identify which cube is connected to which port.
3)  Sometimes switch is connected to another switch, then connect to switch in Computer Room

New office
1)  Cat6 cable only
2)  Install Cisco SRW248G4P 48-Port Switch in Computer Room  (Switch supports IEEE802.3af PoE standard.)
3)  Single cable is extended directly from SRW248G4P switch in Computer Room to each workstation in cubicle.  Each cubicle has RJ45 jack.
4)  Implement VoIP IP Phone (Polycom IP331, which has PC connection)

Polycom IP331 will be plugged into RJ45 jack in cubicle.  Ethernet cable form desktop will be plugged into Polycom IP331.

Based on above scenario, I am not sure that RJ45 jack in cubicle is IEEE802.3af compliant or not, because cable is not connected to Cisco SRW248G4P switch directly.  In this environment, what do I need to do to make RJ45 jack in cubicle IEEE802.3af compliant?   Otherwise, I believe I need to purchase power adaptor for Polycom IP331 for each IP phone.

I apologize for being novice.  I have never used IP phone and PoE.  I am worrying if it does not work correctly.  I appreciate your any comments regarding this issue.  Thank you very much in advance.  / hb
kg6lfzAsked:
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Rick_O_ShayCommented:
With cat 6 wiring systems you should be good.
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Rick_O_ShayCommented:
I am not saying you need cat6 because cat5 is fine too but you mentioned you were re-wiring with cat6. Even existing Cat3 may be used with poe but only for lower power levels.
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TheExpertTakerCommented:
No, POE to 1 device will not follow to another device connected to the integrated switch on the initial telephone.  i.e if I have POE to my IP PHone and the IP phone has 2 LAN Ports, the 2nd LAN port will act as a switch but not provide POE.    You will need a POE injector.  The Polycom will come with a power supply, if not it will be easier to get a POE injector for your IP Phone (or local power supply).

failing this you need 2 direct feeds from your POE switch for the 2 devices.

CAT3 will be troublesome, particularly if you intend of having a lot of network traffic, and worse, if you share the lans with your data.
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aleghartCommented:
>I am not sure that RJ45 jack in cubicle is IEEE802.3af compliant or not, because cable is not connected to Cisco SRW248G4P switch directly.
You can traverse across patch panel and RJ-45 jack, plus patch cables to connect them.  You don't need a patch cable straight to the PoE switch.

>In this environment, what do I need to do to make RJ45 jack in cubicle IEEE802.3af compliant?
Track it backwards:
device (phone, computer, etc.)
stranded core patch cable
RJ-45 jack
solid core cable to server room
rated patch panel with RJ-45 jacks
stranded core patch cable
PoE switch

The signal can take this path end-to-end with no problems, as long as all components are rated Cat5 or better, and are installed properly.

>Otherwise, I believe I need to purchase power adaptor for Polycom IP331 for each IP phone.
Don't bother.  I have boxes of them on a shelf...you won't need them with PoE.

The biggest caveat...how many ports of PoE can you run off of your switch.  I've heard horror stories of people who end up re-purchasing twice as much switch equipment because they could only power up 1/2 the ports.

I have Netgear PoE switches that can run power on all ports at the same time.  Check the specs on yours.
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TheExpertTakerCommented:
agreed, if you are just extending the cable it will work fine, as long as you extend with >=cat5.  but as I read it I think you only have 1 port and wanted 2 devices.
re the POE power, switches that support Full POE give 15W per port, where some only give 7.5W per port, although if you want you can have full 15w for 12 ports, leaving 12 ports as normal switch ports.
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kg6lfzAuthor Commented:
Thank you very much to all of you.  

The switch has 48 ports, but only half (24) can be powered up with 15.4W.  Is it better for me to purchase non-compliant Switch 48-port and buy AC power adaptor for each IP phone, so that I have full 48 port, and no worry to purchase another PoE switch?  I should consider buying PoE switch that can run power on all ports at the same time, however, it sounds very costly.  Any suggestions?  Thank you.
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TheExpertTakerCommented:
what IP phones are you installing?  I use Avaya 16X series and 56X series and they only use 4-5W.  To use 15W per port is very high!  7.5W per port is good enough.  The switch will also let you program which ports get extra power, if needs be.

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aleghartCommented:
In theory, the 1/2 PoE switches are to accomodate 1 phone + 1 computer for each user.  I never liked the idea of running a computer through the built-in switch in a phone.  One more thing to break...especially when the user decides to rearrange things on the desk and starts pulling plugs.

In our case, we have gigabit connections to the desktops, so all are connected to a separate switch stack.

We bought PoE switches that can run all ports powered up.  Reduces the plugs at the desk.  Also, provides phone service for a short time if/when the power goes out.  With locally powered phones, a power dip or loss could render the phone useless.  No way to call for help.

So, if you're using 1/2 PoE switches, use the other half of the plugs for your computers & printers.

If you're using gigabit to the desktop, then get more appropriate switches.  I don't know if Cisco makes any 100% PoE switches.  Ours are from Netgear:

FSM7352PS - 48 ports PoE + stackable
FSM7352P - 24 ports PoE (not stackable)

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kg6lfzAuthor Commented:
Thank you for comments.  It is very helpful.  I never thought ports on switch should be used for particular purposes.  Now I can manage that.  I also did not think that built-in switch in a phone may cause the troubles.  Is it very inconvenient to use built-in switch?  I plan to get Polycom IP331.  Thank you.  
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aleghartCommented:
>Is it very inconvenient to use built-in switch?

Depends if you're using VLANs or running your phones on a separate physical network.  Our phones terminate in different patch panels and use their own switch stack.  There is some routing so that there is access to the LAN for things like FTP and NTP (time sync).

For VLAN passthrough, you need to configure the phone and switch.

Also, our desktops go to a gigabit switch.  Our Polycoms (430, 650) only have a 100BASE-T port.
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kg6lfzAuthor Commented:
Thank you to all.  One last question.  How does desktop plugged  into IP phone get IP address?  I think IP phone has to be fixed, but I want desktop to be DHCP.  Thank you.
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Rick_O_ShayCommented:
If the switches support it you can assign addresses via DHCP relay for both phones and PCs by using a voice VLAN and data VLAN.

Here is a good example of setting it up:

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080114aee.shtml
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TheExpertTakerCommented:
we have many sites with IP phones using 1st connection to POE switch on vlan dhcp with desktop PCs connected to LAN port on phone passthrough on 2nd vlan with dhcp.  
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kg6lfzAuthor Commented:
Thank you very much for all of you.  It was very helpful.  I appreciate it very much.  With all the information, I have better understanding how to configure it.  Many "Thank You" to all.  / hb
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kg6lfzAuthor Commented:
I needed to add another comment to increase points.  I apologize if this is not a correct way of doing this.
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