> Even the telco's breakout of a DS-3 takes more space than you think.How would you troubleshoot one DS0? (Very carefully I'd imagine)
In software, naturally. A physical DS0 needn't exist.
(I can all ready imagine the Inermod/crosstalk, RFI of all those DSP's crammed into a confined space..brrr)
Why would you do something that crazy? You could put 8 high-end DSPs on a half-height PCI card and have each one handle a DS2's worth of channels (up to 96) and then have the 8th do general housekeeping of the entire DS3 and PCI interface. Why would you use one DSP per channel?
-A.
Andrew's points are correct.
There exist already cards that will do this, that are even PCI (CPCI, though.) They tend to be crazy expensive despite relatively inexpensive parts, as has already been noted. They also tend to be surrounded in marketing gobbledy-gook that makes it impossible to determine the true capabilities of the equipment without getting a 'sales engineer' to cut through the BS and tell you what the card actually does. And as a last nail in the coffin, typically these boards are part of larger "architectures" which are impossible to purchase in individually useful or programmable components. ("OH! You want the SOFTWARE LICENSE, then, as well! That's a separate contract and price sheet!")
We here in the Asterisk community sometimes fail to see the larger possibilities that surround us, and focus only on what the hobbyist or single IT person working alone can afford and understand. The telephony hardware market is huge, and has an impressive array of vendors producing some really nice cards. Alas, most of them are overpriced because of the niche nature of some of this gear - if you spend $300,000 developing the hardware, software, and certifications for a card then you can't charge $750 for it, even though that might be the cost of the chips and manufacturing.
We (the * community) have this single-minded focus because of the items I mention in paragraph 1. If it's too difficult to understand, purchase, or if it's too much money to afford experimentation, we won't use it. That's a shame, since I think there could be some really cool parallel-CPU stuff done with third party cards (encryption, transcoding, echo cancellation, faxing) if they became more available and approachable by the open-source community. Look at the neat stuff that OpenBSD does with the PCI-based encryption cards.
I expect a DS-3's worth of physical and transcoding traffic can be pushed through a PCI bus machine and into Asterisk, if the appropriate amount of 'real' development was put towards the effort. ('real' in this context equals a team of developers working full time, for money.) I have some doubts if it could be marketed and sold in a cost-effective manner by anyone other than Digium at this point, though, so it's a moot point.
There have been discussions here on this list already on the availability of boards like SBEI's channelized DS-3 card (they've been a reasonably approachable vendor.) All that we need is what Andrew describes (a few high-end DSP's on a card) and the software extensions to glue all of that into Asterisk. Markets exist for such a combination(I know - I've been in three firms now that would have bought such a system) but the real revenues are out there in the land of slick salespeople and big trade show booths, which jack up the prices out of the range where anyone running Asterisk would be interested. I think if that could be delivered for $5000 (not including the PC) then there would be some buyers. Compare against buying a used (not new) Cisco DS-3 card for a 58xx or a Quintum or a Nuera with the same capacity. I will say that the big problem with this whole discussion is that when you reach DS-3 levels, running PRI just isn't elegant (but certain it's possible.) Implementing SS7 on Asterisk is a much larger issue, and more fraught with danger. That being said, I can also get M-13 DS3-to-T1 muxes pretty cheap these days, so just the space savings of a DS3 into a single Asterisk box still makes it look appealing versus a slew of PRI's and associated card madness.
I don't expect any real comments to come out of this post, and I'm uncertain why I even made it. The people reading this list (you know who you are - Hi, guys!) who have an interest in high-density Asterisk installations have not and will not ever post to this list directly. There are dozens of companies in this situation (ssssssh! It's a secret that they run Asterisk! What embarrassment that an RBOC was using <gasp> OPEN SOURCE!) and it's a shame that this type of platform will not be developed due to everyone's reluctance to practice what they preach with open source information.
Anyone want to fund an egg or a chicken?
JT
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