[asterisk-users] FXS channel banks

[Steve Totaro]

On Fri, Mar 7, 2008 at 8:02 PM, Tzafrir Cohen <tzafrir.cohen at xorcom.com> wrote:
> On Fri, Mar 07, 2008 at 03:00:03PM -0500, Jay R. Ashworth wrote:
>  > On Fri, Mar 07, 2008 at 02:14:57AM +0200, Tzafrir Cohen wrote:
>  > > >    http://www.voipon.co.uk/xorcom-astribank32-32-fxs-channel-bank-p-530.html
>  > > >
>  > > > Trouble is, you'll need 7 32-port units to cover your needs and I'm not
>  > > > sure if USB2 is up to driving that many ... Tzafrir?
>  > >
>  > > One USB connector can take a number close to that easily. But even if
>  > > USB were the bottleneck, you would just add another USB controller in
>  > > the form of PCI card and get extra bandwidth.
>  >
>  > Is there any reason you'd want to do that on a system of that scale
>  > instead of just using Ethernetted FXS boxes on a dedicated 100Base?
>  >
>  > Even if you didn't want to use reinvite, seems you'd still win just
>  > from the less expensive host interface (I can't understand people using
>  > T-1 interfaces for FXS channels either, honestly, in the current
>  > environment).
>
>  USB is very cheap. It's in every computer. A dedicated ethernet segment
>  costs more to set up that an extra USB segment (a 10$ for an extra USB
>  controller? 20$ for a USB hub? a bit more for the wiring?).
>
>  TDMoE is more complicated as the latency is higher and the jitter is
>  larger.
>
>
>  Now both thing have been (T1 channel banks, and TDMoE) have been done by
>  others. People do use and buy them. I don't intend to say that they
>  don't. But ours does as well :-)
>
>
>  --
>                Tzafrir Cohen
>  icq#16849755              jabber:tzafrir.cohen at xorcom.com
>  +972-50-7952406           mailto:tzafrir.cohen at xorcom.com
>  http://www.xorcom.com  iax:guest at local.xorcom.com/tzafrir
>

Ethernet/SIP is going to be by far the most flexible.

You can have much longer cable runs without some kind of USB repeater
device.  Switches are cheap, CAT5/6 is cheap.

You could put a Quintum Tenor AX 48 Port (for instance) in one section
of a building, campus, LAN (WAN if you are daring) and the server
could be anywhere, not tied by 15 or 30 foot USB cables.  Then if you
are doing new wiring, you can run the shortest distance from the
location of the SIP FXS device to the phones.

You can have redundant, self healing links as well as link aggregation.

I cannot see how TDMoE or USB come anywhere close to this flexibility
and certainly don't see it being a fit for high port densities like
discussed.

I see TDM0E as something that a tech guy thought would be cool (and it
is but not very practical) and a USB device something suited for the
SoHo (but missing the scalability, redundancy, and flexibility that IP
gives.)

Thanks,
Steve Totaro