On Tue, 7 Nov 1995, Steven J. Richardson wrote:
Of course you are correct; if you observe the links over a long enough time, you will see loss. I hope that the orders of magnitude between 10% loss and 1E-4/1E-5 make an impression on persons saying that the first number is acceptable.
You are misinterpreting my statements and I think this is because you are forgetting the time element. Even 100% packet loss is acceptable and was frequently occurring on the old NSFnet. If you measure over the time interval that a 1500 byte packet takes to traverse a gateway then loss of a single packet will register as 100% loss. So in order to state what percentage of loss is acceptable and be unambiguously understood, you need to specify the time element. Of course, I am also guilty of not explicitly stating this time element. Then there is the difference between what loss is acceptable and what loss is desired. It is likely that most core NSP's would consider a DESIRABLE packet loss rate over an hour of time to be .001% but it is also possible to simultaneously consider 10% packet loss over the same time period to be ACCEPTABLE as long as it does not occur during more than one hour out of 24. Note the similarities between my statement re 10% and the familiar refrain from polling companies, "accurate to within 2 percentage points 19 times out of 20". To get a REASONABLE standard of packet loss you have to qualify your numbers by saying that a loss rate of .001% 23 hours out of 24 is desirable but a loss rate of 10% 1 hour out of 24 is acceptable. This recognizes the reality of today's global Internet which is not anywhere near fully meshed and which is experiencing sustained surges of growth. Just like in a race condition, sometimes the NSP's will fall behind due to line failures and equipment failures and new equipment shipping failures and so on. We don't get anywhere by slamming NSP's for aberrations even if those aberrations recur on a daily basis for short periods of time because the Model T Ford level of network technology that we are using just doesn't allow them to do much better. Michael Dillon Voice: +1-604-546-8022 Memra Software Inc. Fax: +1-604-542-4130 http://www.memra.com E-mail: michael@memra.com