[asterisk-users] PoE switch recommendations?

[David Gibbons]

Obviously we don't need 1Gb connections for VOIP :)

Phones support pass through to the desktop and VLAN tagging.

The need for 1Gb ports comes from wanting to have 1Gb at the desktop.

Dave

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Gordon Henderson
Sent: Monday, October 06, 2008 11:29 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [asterisk-users] PoE switch recommendations?

On Mon, 6 Oct 2008, Ken D'Ambrosio wrote:

> Hey, all.  We're rolling out VoIP, and I'm wondering about PoE
> recommendations, as we're going to have to replace our current network
> equipment.  My first inclination would be to just plunk down the cash and
> do a Cisco system, but I'm relatively certain that would get shot down by
> finance.  Any recommendations for a couple-hundred-port solution with
> VLANs, PoE, and QoS?  Don't care much if it's in a single chassis or not,
> so long as it has Gbit uplinks.

I'm curious as to why you want Gb uplinks on the switches?

If we assume 100Kb/sec per phone .. (gross rounding, using 100Kb/sec per
phone, rather than ~80 - make the sums easier and builds in a margin) 10
calls per Mb/sec.

So for a 24-port switch, 24 phones all talking to 24 extensions off that
switch, the max the uplink port is going to be pushing out is 2.4Mb/sec.

For 200 extensions, say 9 x 24 port switches, with a single top-level (non
PoE switch) switch with the PBX plugged in along side the 9 downlinks,
that single PBX link will be carrying 2.4*9 = 22Mb/sec if all phones are
in-use at the same time (and the PBX is carrying media)

Now you may not want to build the network like that, but it seems that Gb
is overkill just for the VoIP side of things. (And with that many
extensions, I would suggest keeping all the phones on one set of switches)

(Then again, it might not be possible to get big PoE switches without Gb
uplinks, so it might be a moot point!)

So satisfy my curiosity - why Gb uplinks?

Cheers,

Gordon

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