> I would like to add some information about the capacity of the USB 2.0 > connection. The USB 2.0 interface provides a theoretical speed of > 480,000,000 bits per second. A typical uncompressed phone conversation > uses about 64,000 bits per second per direction, plus some overhead; in > total less than 200,000 bits per second per phone call is used. Thus, the > theoretical concurrent number of conversations that the USB 2.0 > interface can handle is 480,000,000 divided by 200,000: roughly 2,400 calls for a > single USB 2.0 port. For more info, see > http://www.xorcom.com/astribank-technology/usb2-interface.html
Have you done this in production? Is there an actual case study and/or company that is doing this with the hardware that I can speak with? I'd like to see what performance is like with 256 active channels on a USB bus. > Bottom line...the USB connection is not the bottleneck. >From a bandwidth perspective, yes.. but what about 8 devices interrupting on the bus at the same time? What does that do to latency and jitter? > Finding a PC with the required number of PCI slots would be a problem with the suggested > Sangoma solution. How hard is it to find a piece of server hardware w/ two PCI-E slots? If you are going to be running 200+ channels, you better be running a decent enterprise piece of hardware... > As for the channel banks, since the 1U Astribank supports 32 channels > (as opposed to the typical 2U 24 channels supported by other types), the > Astribank is obviously the better choice. >From a real-estate perspective, yes. It would be much better to have 8 1u boxes connected to a pair of 2u servers. I agree it makes the wiring job a lot less complicated. I've just never actually heard of anyone doing this in production. > For a point-by-point comparison, see > http://www.xorcom.com/astribank-technology/astribank-vs-channel-banks.html This discusses nothing about latency or jitter when using 8 devices on the same USB bus. Other than that, it looks like a nice comparison, and there are certainly some perceived advantages. > I'd be happy to answer any other questions about this technology... OK.. 1. Do you have anyone in the field that I can talk to that is running 8 Astribank 32 port units on a single Asterisk server? 2. How do you deal with latency / jitter issues when you have 8 devices interrupting on the USB bus? _______________________________________________ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-biz mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-biz
