POE Injector cause network issues?

I troubleshot a network recently that had some very inconsistent network issues. At times during the day most user's network access was very bad. Ping times were very high with a lot of request time outs.

After ruling out servers and switches I had the cables tested. We found a couple data jacks with shorts in the cabling.

I have never seen a couple bad connections cause these kinds of problems for an entire network. The difference is all workstations have IP phones with POE injectors. Cable runs from the wall jack to the POE injector, POE injector to phone and phone to PC.

Could POE injector with bad cabling cause more problems than bad cabling without POE injectors?

I have no idea why they have a POE injector at each workstation, there are plenty of power outlets. Is there any reason someone would have recommended POE injectors instead of power supplies when there are plenty of power outlets?
ajdratchAsked:
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TimotiStDatacenter TechnicianCommented:
I'd say the problems caused by bad cabling depend a lot on the protection configured on the switches. Flapping ports can cause a lot of issues.
If you have faulty cables between injector and phone, that would be even worse.

There could be political/sales reasons for the injectors:
- Somebody wanted to sell excess injectors,
- Power adapters would have been more expensive,
- Nobody told the installer that there's no POE on-site and he forgot about power bricks completely,
- The injectors were planned in the comms rooms to be supplied with UPS, just somehow ended up with the users.

Tamas
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Dave BaldwinFixer of ProblemsCommented:
Also it is possible that the POE injectors are not rated or designed for the speed of your network.
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wyliecoyoteukIT directorCommented:
The IP phones have a builtin 2 port PoE splitter and switch to provide power and data for the phone and  data for the PC, so PoE with a short, is putting up to 12V into the data port on a switch. Or maybe you are getting SIP phone data on the network ports, or both. No wonder you got problems.
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TimotiStDatacenter TechnicianCommented:
Standard POE is 48V, but it should be facing away from the switch...
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wyliecoyoteukIT directorCommented:
There is a switch in the Phone.
I expect that the shorts in the sockets caused a lot of crosstalk that would go through the transformer to the switch in the phone, or maybe the short caused problems with the 2 powered pairs.
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wyliecoyoteukIT directorCommented:
I have no idea why they have a POE injector at each workstation, there are plenty of power outlets. Is there any reason someone would have recommended POE injectors instead of power supplies when there are plenty of power outlets?

How are these wired? Wouldn't the injectors need power supplies anyway?
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wyliecoyoteukIT directorCommented:
Could these unitas be PoE splitters, not injectors?
If so, it changes the whole scenario, and they may not even be required, if the phones support PoE.
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