[asterisk-users] Teliax Quality of Service

[SIP]

Trevor G. Hammonds wrote:
> From: SIP
> Sent: Saturday, August 04, 2007 2:57 PM
>
>   
>> Stephen Bosch wrote:
>>     
>>> Douglas Garstang wrote:
>>>   
>>>       
>>>> I confused by this. Don't ITSP's have redundancy? Don't they have
>>>> multiple edge systems for accepting incoming calls? Don't their multiple
>>>> edge systems have multiple interfaces, connected to multiple subnets,
>>>> via multiple switches? And, don't they have multiple upstream providers?
>>>> About the only thing that could go wrong that affects all service like
>>>> this would be a badly pushed out software update, affecting all systems?
>>>>         
>>>     
>>>
>>> Don't be confused. The answer to most of your questions is no.
>>>
>>> Barriers to entry are too small for ITSPs, and there are lots of
>>> basement operations masquerading as big carriers.
>>>
>>> -Stephen-
>>>
>>>   
>>>       
>> There are also lots of big carriers masquerading as big carriers. ;)
>>
>>
>> If the ONLY people who could get into the business were the ones who 
>> could, before offering any services to customers, afford to build out 
>> multiple edge systems for accepting incoming calls, each with multiple 
>> interfaces connected to multiple subnets via multiple switches using 
>> multiple upstream providers, you would have ONE single choice for an ITSP.
>>
>> And AT&T doesn't have that amount of redundancy in their network. 
>> Working in the carrier networking business, I can assure you that we've 
>> NEVER run across a SINGLE carrier network (not from the largest to the 
>> smallest) that has redundancy in ALL aspects (or even MOST aspects) of 
>> its network. This is why there are uptime policies that allow a 
>> percentage of outages to occur. Triple 9 uptime (Exceedingly rare, but a 
>> purported goal -- 99.999%) still allows 15 full hours of downtime a 
>> year. And that rarely includes the occasional lost packet or latency.
>>     
>
> Your math is incorrect.  FIVE nines (99.999) allows only 5.26 MINUTES of
> annual downtime.  Triple nine (99.9%) allows for 8.76 hours of annual
> downtime.  Keep in mind that most SLAs do not include "planned" maintenance
> in their guaranteed uptime.
>   
You are quite right, sir. I've no idea what I was doing with my math 
there. I can't even REPLICATE what I was doing with my math there.

N.