[asterisk-users] PoE switch recommendations?

[Robert Augustyn]

Most phones support only 100M switching though .... Unless you run separate
cabling for VoIP and data but then you would not need the 1G uplink. 

> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com 
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of 
> David Gibbons
> Sent: Monday, October 06, 2008 11:48 AM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [asterisk-users] PoE switch recommendations?
> 
> 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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