10-07-2009 03:48 AM - edited 03-15-2019 07:57 PM
Hello,
We are designing a 520 Ip Phones UCC solution for a client, the LAN Switches we are proposing are 3750G-48PS and the 520 IP Phones we are proposing are 7945G.
On the 7945G Product Overview page:
we see that the phone Power supports IEEE 802.3af PoE (Class 3).
and for the 3750G-48PS POE Switch:
http://www.cisco.com/en/US/products/hw/switches/ps5023/prod_models_comparison.html
we see under the 'PoE Class 2/PoE Class 3 Devices Supported' column that only 24 PoE Class 3 devices are supported.
Does that mean that the 7945G being PoE Class 3, the 48 port PoE LAN Switch will only support 24 7945 phones?
And, if yes, is there a way to 'tweak' the LAN Switch Power settings, or feed in more power to the LAN switch, to make it support all 48 ports for Class 3 PoE devices.
Thanks & Regards,
Kartik Bhatia
10-07-2009 03:53 AM
Correct, you could use the 7942 that are poe class 2, or 2x 2960PS 24 ports instead of the 3750.
10-07-2009 04:42 AM
Thanks ...
1. Using the 2x 2960PS 24 ports will allow me to PoE 48 7945 phones? I mean, does a 2960PS supports all 24 ports for Class 3 PoE?
2. ALso, is there a way to 'tweak' the 37xx LAN Switch Power settings, or feed in more power to the LAN switch, to make it support all 48 ports for Class 3 PoE devices?
10-07-2009 05:46 AM
1 last thing:
I do not see 2960PS or any 29xx switch which supports all ports for Class 3 PoE:
Kindly Assist
10-07-2009 04:44 AM
Hi Kartik,
It's excellent that you picked up on this before moving ahead :) Just to add a note to the great tips from my good friend Paolo (+5 ponts here buddy!)
WS-C3750E-48PD1150W = 48x 7945/7965
WS-C3750G-48PS = 30x 7945/7965
When making these decisions, this is a very valuable tool;
PoE calculator
Use http://tools.cisco.com/cpc/launch.jsp
Cheers!
Rob
10-07-2009 05:12 AM
Hmmmm...
Me confused now, even though it says 48 Ethernet 10/100/1000 ports with PoE BUT the link:
http://www.cisco.com/en/US/products/ps7077/prod_models_comparison.html
clearly says under 'PoE Class 2/PoE Class 3 Devices Supported' as 48/24
???
10-07-2009 05:15 AM
And the same links talks about 3750E-48PD-F to supprt 48 ports
:-)
How can I miss that.
Got it now, thanks Rob and p.bevilacque
10-07-2009 05:20 AM
Hi Kartik,
The bottom line here is that the 7945 is not a "true" Class 3 device in that it actually uses 12w vs 15.4w for Class 3 devices.
If you are looking at putting in 48 (7945) phones you can either uses 2x24 port 2960's as paolo nicely noted or 1x WS-C3750E-48PD1150W = 48x 7945/7965
Hope this helps!
Rob
10-07-2009 05:35 AM
Got ir... one last thing though:
1. I do nto see any 2960 switch which supports all ports on Class 3 PoE:
2. No tweaking possible to make a 3750 G switch support all ports on CLass 3 PoE - coz E series are Class 3 switches - much expensive.
10-07-2009 06:09 AM
Hi Kartik,
No worries :)
1. From the doc you linked;
Cisco Catalyst 2960-24PC-L can support 24 simultaneous full-powered PoE port at 15.4W.
2. Sorry my friend, no "magic" tweaks.
Cheers!
Rob
10-07-2009 06:12 AM
Ya I saw that before but sorry I forgot to tell this - only GIG LAN Switches
Requirement is GIG LAN ata each node - so can not go for 10/100 Phone like 7941/7942 or 10/100 LAN Switches
:-)
10-07-2009 06:28 AM
Right. Want much = spend much.
10-07-2009 06:31 AM
lol... got it
thanks
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