[asterisk-users] Where is the Digium DS3 card?

[Alex Balashov]

Steve Totaro wrote:

> 7 HP DL320s, RAID 1 with Quad Sangoma.  Not a dozen but more than
> twice that, 28 T1s.  What is your cheaper solution?  Also, have two
> cold spares in the rack.  DL 320s are cheap and "rarely fail" using
> 1.2.X.  I actually cannot remember a single failure over years of
> operation.

My solution, if we may call it that, is certainly not cheaper.  It is 
not always about price.  There's that whole value thing, too.  :)

The point I was trying to get at earlier is that if one has unused DS1 
carriers on a DS3 and you are debating extra cold-spare PCs with T1 
cards to provide failover in a PRI hunt group because one literally 
cannot afford downtime at the statistical incidence typically incurred 
by the failure of industrial DS3 interface equipment, one is probably 
chasing their tail and needs to rethink one's strategy at a much higher 
level than simply the question of terminating equipment.

> I don't think you have much experience with DS3s, correct me if I am wrong.

I do.

> While pricing many solutions, it is either 14 or 16 T1s where a DS3
> becomes about the same cost for the loop, that is a lot of wiggle
> room.  

A bit of a digression, but:

That is commonly the case, indeed, with "many solutions."  It is also 
commonly not the case.  Sadly, this topic lends itself to generalisation 
not;  if it did, our lives would be considerably simplified and a 
marketplace rationale value chain consisting of a whole slew of agents, 
resellers and brokers would cease to exist.

It all depends on who the transport vendor is, if it's an ILEC, and if 
so, which ILEC, which LATA, applicable tariffs, forebearances, whether 
there is inter-CO mileage, etc.  If it's a CLEC, it's a question of 
whether there are blacklisted COs in the span design, the price of their 
CFA.  If it's a retailer of Bell services it's all a question of what 
kind of pricing and options _they_ get, and whether the DS3 is delivered 
over regulated, UNE-subject copper, etc.

I have been in situations where it is more economical to get a DS3 after 
about 5 T1s because the DS3 was built over leased utility dark fibre in 
a metro area.  I have also been in situations where even 20 T1s are 
cheaper than a DS3 loop because of the particular facilities and various 
pricing/tariff absurdities that are so characteristic of ILECs.  I have 
also seen on more than one occasion where a stupidly large number of 
distinct analog lines (as in, pairs all the way from the MDF, not even 
GR.303/DLC-delivered stuff!) was cheaper than using T1 as a carrier for 
an equivalent number.  Something about USF subsidies in rural areas 
*cough* *cough*.

It all depends.

> Read the specs on the Adtran 2800 MX13.  I don't think it is going to
> fail unless you smash it or pour coffee on it.  Google it and RTFM
> before you spout off about a product you obviously have no knowledge
> of.

I have used the Adtran M13 muxes, and I postulate nothing about them 
save that it has the common liabilities of all electronic devices 
composed of matter and compliant with the laws of physics and the 
discovered properties of the known natural universe.  They can and will 
break.

No, seriously, I agree -- be it an Adtran or a Widebank or whatever, 
it's pretty hard for an M13 mux to blow.  It's almost something you have 
to really want to happen.

But do realise the sort of equipment toward which I am gesturing is 
engineered to a similar level of reliability, proportionally, as much as 
is possible in light of increased complexity and composition.

> We are talking DS3 here, not OC12.  Talk about overkill.

What is fundamentally different?  Both are used as transport facility 
for high-density inter-machine trunking.  One does not need native SONET 
to have a need for extremely high TDM circuit availability.

No, you do not need the level of redundancy I am suggesting in the sort 
applications being discussed.  That's the whole point.  If, on the other 
hand, you do, to the point where you're fretting about a DS3 interface 
on a commercial VoIP gateway failing vs. having a bunch of PCs with 
broken-out T1s, then it might be worth the investment to overengineer in 
a manner that corresponds to telco environment requirements.

> They are essentially small servers, some with solid state and flash,
> others with real hard drives.  Ever open one up?  I would prefer to
> pop a case and replace a T Card, memory, hardrive, powersupply, fan,
> then waiting on an RMA.  Especially when your call center is losing
> $26k an hour.

This is true, PCs are easier to deal with when they fail.  No question 
about that.

On the other hand, Cisco AS equipment is that much less likely to fail. 
  Keep one cold spare around and you're good.

-- 
Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
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