[Asterisk-Users] Systems Admin; Telecom Newbie - What do I need?

[Tom Rymes]

On Jul 14, 2005, at 12:32 PM, Ed Pastore wrote:

> On Jul 14, 2005, at 11:54 AM, Adam Goryachev wrote:
>
>
>> Use a phone like the polycom IP301/501/600 which has a built-in 2  
>> port
>> 10/100 switch. ie, take the existing cable and plug it into the  
>> phone,
>> then take a second cable, connect one end to the phone, and the  
>> other to
>> your PC. No need for any additional major investment....
>>
>
> Independent of my telephony overhaul, I am planning on migrating my  
> network to gigabit to speed up some core file services (we do a lot  
> of server-based computing). Are there phones with a gigabit switch  
> in them? :)
>
> Or, kludgy though it seems to me, is it realistic to suggest buying  
> an el-cheapo unmanaged gigabit switch for every office? Looks like  
> I could get away with $50 per node...
> http://www.cdw.com/shop/products/default.aspx?EDC=652855
>
> From a network admin's perspective, that seems to me like asking  
> for trouble. But routing packets really isn't my specialty, so I  
> don't know if it would really cause any problems.

I would think that, though less than ideal, you could purchase  
Netgear switches <http://dealmac.com/artclick.html?91089,130404> for  
$35 each and install them at each desk, or each cluster of desks.  
This will almost certainly be faster than 100Mbit, but not as fast as  
if you plugged the computers directly into a higher-end switch (I  
don't know how much traffic the backplane of those little switches  
can handle.). Also, I would not give up entirely on the cat3 cable,  
but it all depends on what you have. If you have 4-pair cat-3, you  
can punch it down into RJ-45 jacks and run 10-baseT over that wire. I  
think it might even work if you don't have the 4-pairs, but I would  
have to research that first. The trick with running 10-BaseT over  
cat-3 is that you have to either use a 10-BaseT hub to force  
everything to the slower speed, or you have to manually set either  
the device (PC, Phone, etc) or the switch port to 10-Mbit. If you  
connect two 100-Mbit devices set to auto-negotiate speed across cat-3  
cable, they will negotiate to 100-Mbit and then fail to work over the  
cat-3. However, if you buy a managed switch, you can set all of the  
ports to 10-Mbit, that will work nicely.  The other option would be  
to use a 10-baseT hub, but as someone else mentioned, that's not a  
good idea. If the only traffic you are sending over the cat-3 is  
voice, 10-Mbit should be plenty of bandwidth, so I wouldn't let that  
stop you.

Another option you could pursue is to use ADSI phones over the  
existing wiring that your comdial uses, instead of using SIP phones.  
This eliminates your wiring problem, but ADSI phones have their own  
limitations. See <http://www.telephonyware.com/telephonyware/scan/ 
fi=products/st=db/co=yes/sf=category/se=Analog%20Phones/op=eq/ 
tf=category%2Cdescription.html?id=TQeJLrQ4> for some examples of  
these phones. Using ADSI would involve hooking up multiple channel  
banks to a multi-port t1 card in the * system to achieve 60 channels.  
The phones are slightly less expensive, but the cost of the channel  
banks and the T1 card makes the cost mostly comparable to a SIP  
phone, but at least you would not have to change your wiring.

All in all, you can definitely make this happen with your current  
situation, but there are a number of different options out there, and  
it's all one sort of tradeoff or another. My preference would be:

1.) Add a second physical port to each location by pulling wire. If  
that is not an option:
2.) Explore running your existing phone wiring at 10-baseT using a  
switch, and barring that:
3.) Look at using the little gigabit switches to share the network  
between your phones and your PCs. Of course, if you share the voice  
and data network, you then have to worry about QOS, because your  
voice quality will degrade if someone makes a large file transfer  
over the network. Since you seem to be putting a lot of data across  
your network, you might think twice about sharing the wires,  
especially because option 1 probably won't cost much more than 60  
small gigabit switches and you won't have to worry about QOS because  
all of your data and voice traffic runs on different physical  
networks. Finally:
4.) Use ADSI screenphones and channel banks.

Phew! Again, you might want to consider contacting someone to help  
you wade through the different possiblities, especially considering  
how important telephone systems are to businesses, and how reliable  
most bosses expect their phones to be.

Tom