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Teleco - IP Office Cabling - Cat3 patch panel?

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edhead

IS-IT--Management
May 1, 2002
101
US
My company is having an IP Office phone system installed and I have been asked to install the wiring for the digital phones. Someone else has already run the cable - Cat3 - and our phone vendor says we just need to terminate the cable to a patch panel to interface with the IP Office. My question is do I have to use a Cat3 patch panel (I am having a hard time even finding one) or can I use a Cat5 / 5e patch panel and if I can what would the pin out be. I have pulled data cable before but never telco so I am looking for some help.
 
You can get 6p6c jacks for most of the patch panels that accept modules.
 
To quote a great Dectective-"I also confused"...Cat 5e is speced for new installations of anything these days and the cost difference is not worth mentioning. Did someone in "Sales" say the existing Cat 3 (are these 25 pair) would work or did "someone" go out of their way to pull Cat3? Anyway, last Cisco IP phones I did worked on standard Cat5 jacks and pinning-after all it's data. As far as Cat 3 working, it may-it's not a lot of data. It does makes sense to develop a modern phone system that would work on its predecesors infrastructure. However, distances will be shorter as the old phones would work considerably farther than data nowadays will support. A call to AVAYA or Panasonic "tech support" (or other reseller) would also help you decide if Cat 3 will be a go. Bottom line-why install Cat 3 anyway?
[yinyang] Bob
 
To finish-if you decide Cat 3 will work-punch it down to Cat5 (somebody will need the panel later). The 6p6c jacks have the same pinning on 3456. 8p jacks will work as a 6p plug will center itself in an 8p jack. Check it out but I believe the new phones will have 8p deskset plugs anyway. Check out all the new phone stuff to ensure you get the right ports...
[yinyang] Bob
 
Well, I thought IP office required a 100MBit switched network, which would inherently require Cat5e... at least to be stable.

Furthermore, usually you put it on the same network as your computers use, and then use QOS on your switches to divide the bandwidth appropriately... so I don't understand why Cat-3 is even being mentioned or considered.
 
Ask the guy who sold the phone system why. They may not be brand name and also may run on their own switch's. This is just "an IP Office" vendor- For the sake of getting more info out of him I'm just being general and speculating...Edhead?
 
Since the cable is already placed, I would go ahead and use cat 5 patch panels, just make sure you document that the cabling is only cat 3 and therefore you only have the possibility of a 10 Base T network. You will need to use 8P8C jacks since you will be running data also on this system. Well I assume you would be since it is an IP system.
You have to be careful how many hubs or switches you use when running VoIP.
Most IP systems will only use a max of about 80 Kbps so it will work on a 10 Mbs network.
Cat 5e would be better, but live and learn they say.


Richard S. Anderson, RCDD
 
It may work... but boy, I'd be sketchy on this one. But then again, what can you do if you've already got your prewire complete...

I just never knew that you could even do it over a 10baseT network considering that the priority of the voice packets would really degrade the remaining network capacity.

I think avaya has a calculator for the number of stations assuming a ratio of usage, etc. etc. and it'll tell you how much throughput it will use, I can't remember where I saw that though... maybe in an IP office brochure.
 
Think about what a T1 line is:
A T1 line can carry 24 digitized voice channels, or it can carry data at a rate of 1.544 megabits per second.
So running VoIP over a 10 megabit system should work fine, it just may bottleneck data transmission at times.
All depends on the hardware setup.

Richard S. Anderson, RCDD
 
VoIP does not generate a lot of traffic, what it DOES generate is traffic that can not afford to wait or be dropped. With 1000 phones at my employer, we just barely generate 10 meg of traffic. It can not be put in a 10 meg pipe however as no packet can afford to wait its turn, we run it in 100 meg and gig trunks so it never needs to wait.

I have no trouble visualizing VoIP over a 'modern' 10 meg with QOS and ideally full duplex to end user devices, so long as the upstream aggregate trunks are 100 meg or better.

I do worry that a 10/100 card may (not knowing they are on Cat3) try to acheive 100/full and fail, you may need managed switches to allow you to hard code 10 meg at the switch, but you want switch management to enforce QOS anyway

10/Auto at the switch, and Auto at the card over Cat 3 is ugly but doable, if the switch can't do 10/auto 10/Full at the switch and 10/Full at the card is even uglier but doable. ( you would have to hand configure every station, rather than just the switches)

If I had to accept 10/Half at the Card and Auto at the switch I would start using weasel words with my bosses about how well this would work. (when I started VoIP with Nortel their gear was 10/Half, so it can work, but you need to really eleminate all other traffic)

You need to stress that there can be no hubs or unmanaged switches anywhere in the network that does VoIP, if your company has folks who add to the network without supervision you will start finding them all over when you begin doing VoIP, look for multiple MAC addresses on what you thought was a single port.

I tried to remain child-like, all I acheived was childish.
 
I agree... keeping in mind that any switch that has QOS has managment capability (port speed settings, port lockout... etc, and you can also force one mac address per port if so desired, or if you're using DHCP -- ACL's).

Lots of options...

Point being, which I think jimbo summed up just as well:

If you have a 10MBit network, and you plan on using both data and a fair amount of stations, I think you might be in trouble. Not that you'd encounter any problems on the voice side, but on the data side -- you might see some serious problems if you have a fair amount of voice traffic.

 
The Cat3 wiring is for digitial phones not IP. They are running off of the IP Office Digital station module. We are using IP phones for some remote locations and those are all wired Cat5e at those locations.

The wiring from the IP Office would be patch cable from the Digital Staion Module - to patch panel - Cat3 to do digital handset...

 
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