Inline power options for VOIP phones

Archived from groups: comp.dcom.voice-over-ip (More info?)

hal@nospam.com wrote:




> Has anyone taken a close look at cost comparisons between using inline
> powered switches vs. UPS power backup at the client station? It is
> cost effective to use inline power? Per port costs seem to be close
> to 3X with Cisco modules. Are there stand alone units installed
> inline between the switch and client device that provide power or is
> the present only option to use powered switches or switch modules? I
> had heard that if using Cisco powered modules and non-Cisco phones you
> need a converter dongle. Is that still true?

> thanks

> Hal

You can buy a device designed specifically to sit between your regular,
non IEEE 802.2af - compliant switch and supply power to a 802.3af -
compliant terminal device, such as VoIP phone. They are called mid-span
power supplies. PowerDsine makes those (as well as other people) and sells
under OEM to lots of other (bigger name) manufacturers. They come in
different port quantities between 1 and 24.

As far as costs are concerned, it has been a conventional wisdom that it
is cheaper to have a UPS-protected mid-span power supply to send the
inline power to the phones than to have a UPS installed at every phone
location (and much more elegant if you ask me). However, with the prices
of low-end UPSes falling, I'm not sure the common wisdom would survive
scrutiny if someone was actually to look at the price difference. Besides,
distributed UPSes help to get rid of the single point of failure problem.
Anyways, I can buy a 350VA UPS that would power a VoIP phone for as much
as 45 minutes to an hour for $35, and every IEEE 802.3af port (midspan or
switch upgrade) costs on the order of $50. So, customer's convenience
aside, I think remote UPSes may be a cheaper solution, and less prone to
failure.

--
Dmitri Abaimov, RCDD
http://www.cabling-design.com
Cabling Forum, color codes, pinouts and other useful resources for
premises cabling users and pros
http://www.cabling-design.com/homecabling
Residential Cabling Guide
-------------------------------------





##-----------------------------------------------##
Article posted with Cabling-Design.com Newsgroup Archive
http://www.cabling-design.com/forums
no-spam read and post WWW interface to your favorite newsgroup -
comp.dcom.voice-over-ip - 12188 messages and counting!
##-----------------------------------------------##

Archived from groups: comp.dcom.voice-over-ip (More info?)

"Dmitri(Cabling-Design.com)" <info_at_cabling-design_dot_com@foo.com> wrote
in message news:1098301727.fSJZz8nB2WCq4rkWQYzNiQ@bubbanews...
> hal@nospam.com wrote:
>
>
>
>
> > Has anyone taken a close look at cost comparisons between using inline
> > powered switches vs. UPS power backup at the client station? It is
> > cost effective to use inline power? Per port costs seem to be close
> > to 3X with Cisco modules.

Depends on what you compare - chassis blades are a small uplift (most of the
recent ones use a daughtercard on a non 802.3af module), but inline power is
not available on the cheaper cisco stackable switches, so that could affect
the relative cost.

Are there stand alone units installed
> > inline between the switch and client device that provide power or is
> > the present only option to use powered switches or switch modules? I
> > had heard that if using Cisco powered modules and non-Cisco phones you
> > need a converter dongle. Is that still true?

ignoring exactly which inline power system you use - you will still need a
UPS on the ethernet switch and other central kit.

Cisco are starting to support 802.3af on their kit - but i am not sure if
any of the phones have migrated yet - you need to check the spec.
>
> > thanks
>
> > Hal
>
> You can buy a device designed specifically to sit between your regular,
> non IEEE 802.2af - compliant switch and supply power to a 802.3af -
> compliant terminal device, such as VoIP phone. They are called mid-span
> power supplies. PowerDsine makes those (as well as other people) and sells
> under OEM to lots of other (bigger name) manufacturers. They come in
> different port quantities between 1 and 24.

last time i checked power dsine costs - a patch panel was about the same as
buying a cisco inline power switch with the same number of ports. given that
it sounds like you have to buy the switch anyway.....

an inline power switch is simpler since you avoid the wiring complications
for the in span system,

> As far as costs are concerned, it has been a conventional wisdom that it
> is cheaper to have a UPS-protected mid-span power supply to send the
> inline power to the phones than to have a UPS installed at every phone
> location (and much more elegant if you ask me). However, with the prices
> of low-end UPSes falling, I'm not sure the common wisdom would survive
> scrutiny if someone was actually to look at the price difference. Besides,
> distributed UPSes help to get rid of the single point of failure problem.

standard practice is use a dual power switch, and use UPS on 1 feed, so loss
of UPS doesnt kill the switch.

this tends to push you onto chassis switches with the cisco range (none of
the stackables comes with dual power - you use an external dual feed power
system) - Catalyst 4500s is the common choice for a chassis switch for a
wiring closet.

> Anyways, I can buy a 350VA UPS that would power a VoIP phone for as much
> as 45 minutes to an hour for $35, and every IEEE 802.3af port (midspan or
> switch upgrade) costs on the order of $50. So, customer's convenience
> aside, I think remote UPSes may be a cheaper solution, and less prone to
> failure.
>
> --
> Dmitri Abaimov, RCDD
> http://www.cabling-design.com
> Cabling Forum, color codes, pinouts and other useful resources for
> premises cabling users and pros
> http://www.cabling-design.com/homecabling
> Residential Cabling Guide
> -------------------------------------
>
>
>
>
>
> ##-----------------------------------------------##
> Article posted with Cabling-Design.com Newsgroup Archive
> http://www.cabling-design.com/forums
> no-spam read and post WWW interface to your favorite newsgroup -
> comp.dcom.voice-over-ip - 12188 messages and counting!
> ##-----------------------------------------------##
--
Regards

Stephen Hope - return address needs fewer xxs