I think the desired goal here is to separate the access SLA from the backbone SLA. That is, consider a simple picture: Network Cloud------Provider Edge Router-----Local Loop-----Customer Router Network availability is the % of the time the customer router and provider edge router can communicate, and is designed to measure if the local loop is up. For instance, let's say the provider edge router looses all its uplinks to the Network Cloud, your local loop is up and functioing but you have 100% packet loss to all destinations. The "packet loss" SLA kicks in on a per-destination basis. Everything is up and working, but the provider has a full circuit and is dropping 20% of the packets on that link. You catch it, you get a credit. I think the technical reason why these are separate has to do with the expectations. If my local loop is dropping 0.5% of the packets due to errors, it is broken and must be fixed. If some random destination on the Internet is dropping 0.5% of the packets well, that's a normal day in the life of the network. Plus, if your local loop takes errors then you get a credit. However, if there's a full link in the backbone but none of your packets take it, and thus you are unaffected, you don't. Now, having said all that, and having been one of the people who've attempted to communicate sane, rational, technical ideas to marketing and legal the chance that anything sane made it in the actual contract is, well, nil. -- Leo Bicknell - bicknell@ufp.org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/