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

[Wiley Siler]

Let me expand on the bandwidth point HTH made and maybe shed light on
your requirements....

A 100baseT switched (no hubs) network has a lot of bandwidth when you
think in terms of VoIP.  The uLaw stream (uncompressed) from an IP500
phone to the Asterisk box is not going to take more than 80K of bandwith
from the bandwidth pool.  That means 60 phones ALL in a single call
would only be using around 5 megs of throughput.  At that point packet
scheduling becomes far more important than bandwidth.  Gigabit is nice
but the value of QoS in comparison is very evident.  If cost becomes a
driving factor, you may want to focus on upgrading port count and remain
at 100baseT instead of going to Gigabit.  A properly configured 100baseT
network with good QoS rules will yield great performance over an
unregulated 100baseT network.  Do you know your real traffic needs?  I
would check how much traffic is via user download, www browsing,
streaming, email, etc, etc...  You may find that some simple rules save
you quite a bit of cash.  Just a thought and alternative... Gigabit is
also very tempting so that whole spiel may have been for not.  8)

Also, pay heed to the PoE stuff you are hearing about.  I may be wrong
but I am pretty sure you want to be careful what you connect to a PoE
port.  Otherwise you wind up with fried PoE injectors and end devices.
I believe PoE ports would only be used for a PoE phone in essence.  Just
as a reminder and warning.

Cheers,
Wiley





-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Colin
Anderson
Sent: Thursday, July 14, 2005 8:47 AM
To: 'Asterisk Users Mailing List - Non-Commercial Discussion'
Subject: RE: [Asterisk-Users] Systems Admin; Telecom Newbie - What do I
ne ed?

>But currently, I only have one ethernet jack per office. Routing  
>another 60 or so ports would add a very substantial expense in both  
>cabling and backbone expansion (what category ethernet is required,  
>BTW?).

Most decent phones have an ethernet passthrough (2 port) so you can plug
in
your PC. As long as your LAN is decent (Cat5 100baseT switched) the
overhead
using VoIP is negligible. 

I have used the 3Com NJ wall jacks with good success:

http://www.3com.com/products/en_US/detail.jsp?tab=features&pathtype=purc
hase
&sku=3CNJ90

It's basically a 4 port switch that you replace your wall jack with. I
used
the NJ200, it allows you to set priority per port, although I think they
are
discontinued now. In combination with a 3Com power over Ethernet
injector, I
was able to expand a 24 port LAN to a 96 port LAN with a per-port cost
of
$62 Cdn. And, 24 ports of those 96 are PoE, so I can plug my phones
right in
to port 1 and they power up, no external power supply needed. 

hth
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