jhawk@bbnplanet.COM (John Hawkinson) writes:
Most carries have "performance objectives" which they adhere to, and they specify some number of errored seconds per day per circuit, and those numbers may vary based on route-milage.
Unfortunately I think most of those numbers are covered under NDAs, but I can safely say that 1 errored second/day would be well under the criteria and 1,000 would be well over, and anything in between depends on your carrier and route miles, etc., etc.
In most cases, DS3's are sold by carriers as a tariffed service. The carrier may not like disclosing the numbers, but buried in the public tariff's "incorporated by reference" list of documents are the performance objective for that carrier's DS3 service. Most carriers' tariffs refer back to either Bellcore(telcordia), ANSI/T1 or ITU specifications (generally in that order). However, I'm not sure knowing them will do you much good. I tracked down the numbers for DS1 once upon a time. Like any good-one-sided telco tariff, the circuit could be very bad and still meet the "acceptable" performance objectives for the service. If I recall correctly, a DS1 could have several thousand error seconds a day, and be considered "acceptable" according to the tariff. I've never looked up the DS3 numbers, so I don't know the official tariff numbers. As always, the tariff overrides anything the sales person told you, or anything written in your contract. However after saying that, digital lines usually only have 'noise' for a reason. The question is how bad does it have to be before you can get the telco to track it down. Here are my rules of thumb for most digital circuits: Error seconds/15 minutes Classification 0 Perfect 1-5 Look at the circuit during the next maintenance window if it doesn't clear up 6-29 Open a ticket 30+ Immediate action required (its likely the circuit is bouncing or 'down' at this point) Other people prefer to use a long-term bit error-rate, or packet/cell errors. But then you have to explain to the telco what a packet or bit is. For those ISPs which own their facility provider, they may be able to get the facility folks to monitor the circuits. But for the rest of us, you have to monitor your own circuits. The facility provider is never going to tell you about a potential problem. -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation
I wanted to pipe in and repeat something I heard. It might have been written in a local ILEC tariff or something I heard as a verbal explanation. You will find availability (% uptime or % error free) numbers in some/most/all? tariffs. The "fine print" is that the availability number given is calculated across everyone's circuits, not yours. So any "guarantee" you might infer is probably much weaker than you might originally have thought. -Mark (not speaking for my employer or anyone else in particular) (btw, last I checked aal5 reassembly errors - which are usually due to dropped cells - show up as CRC errors on a cisco router interface) At 05:37 PM 6/14/99 -0500, Sean Donelan wrote:
However, I'm not sure knowing them will do you much good. I tracked down the numbers for DS1 once upon a time. Like any good-one-sided telco tariff, the circuit could be very bad and still meet the "acceptable" performance objectives for the service. If I recall correctly, a DS1 could have several thousand error seconds a day, and be considered "acceptable" according to the tariff. I've never looked up the DS3 numbers, so I don't know the official tariff numbers. As always, the tariff overrides anything the sales person told you, or anything written in your contract.
participants (2)
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Mark A. Cnota -
Sean Donelan