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. > Face it. If you want service that never goes down, you're either able to > pay the hundreds of millions to provide your own networks and build out > your own redundancy, or you're stuck in the same boat with the rest of > us -- be it that you choose a gigantic carrier or a mom 'n' pop ITSP. > > N. h Trevor Hammonds _______________________________________________ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
