SF-200-24P switch -PoE on Older C-7960 IP Phones

[scunning]

Question regards PoE on older devices

PoE works fine with C 1131/1141 Access Points and C-7975 IP phone

but PoE does not seem to work on 7960 Phones nor on the C-1121 Access points

All devices work properly with the Cisco power injectors or on a Cisco Cat-29XX switch

Is there a trick to make PoE work for older devices ?

   Thank you

steve

[Leo Laohoo]

Hmmmm ... Don't know about those switches but on older Catalyst switches the command "power inline delay shutdown 20 initial 30" sometimes works.

[scunning]

Nice thought thank you

but no Command Line on these small Biz switches

and nothing in the GUI looks like this commend

steve

[Ivor Diedricks]

7960 does not support the 802.3af POE standard (it supports Cisco pre-standard POE) while the switches support the 802.3af standard exclusively. All the newer Cisco phones and APs support the standard.

Ivor

[scunning]

Ivor

I feared that, .  I wonder if there is a wiring or dongal way around this issue ?   I have run Cisco 7960 phones on AF power devices using a dongal or specialcable in which the standrd 568B cable is construtced at one end and on the other end the Blue Pair and Brown pair are swapped.   This worked well with Power Dsine equipment and in fact they manufatured a dongal.   Unfortunately I tried one and no luck.  Somehow this Cisco switch does not act the same way as the Power Dsine power injector.

It's a shame that every current Cisco brand switch will happily support  pre-802.3af but the small business model does not !  A Cat-2960 or Cat-3560 will power up these older units without any issue, and no dongal either

Thank you for the insight I must do some further fiddling.

[Ivor Diedricks]

Unforunately you cannot get around it with a dongle. You can use an Aironet Power Injector which supports pre-standard POE as well as 802.3af - AIR-PWRINJ3. The SF200 switches are 802.3af standards-compliant exclusively. The standard was ratified back in 2003 and all products Cisco has delivered from that time supports the standard. There are numerous Cisco phones supporting the standard as shown in the following link:

http://www.cisco.com/en/US/products/hw/phones/ps379/products_qanda_item09186a00808996f3.shtml

[Leo Laohoo]

Ivor's right.  You either get a power brick or a power injector (PWR-INJ3)+power brick to get this working.  Not sure if you can still find PWR-INJ3 for sale but if you want we got alot of surplus PWR-INJ3 (plus the power brick) and PWR-INJ4.  

[scunning]

I am afraid that both of your are correct

I am just surprised that Dongels work with outer PoE (802.3AF compliant ) power supplys but not Cisco's own Small Biz switches

I wonder what they did to remove the possibility of a dongal to make things works.

Yes I do have some Power Bricks and also some injectors and they work fine but thank you so much for the offer.   I was hoping for an Injector Free installation . . .  Oh Well

Do you guys happen to know if the Small Business ESW-540 switches are just as "broken" ?

thanks

steve