> <[EMAIL PROTECTED]> wrote: > > Unfortunately, 2 ADSLs/SDSL cannot provide high availability due to > the same > > infrastructure being used. > > > > If you need redundancy, try a DSL and a cable TV broadband or leased > line. > > Ensuring that the leased line goes through different exchanges to the > ADSL circuit....
...and that they don't all cross the country on the same fibre route. (though, you probably won't be able to determine this in the case of these consumer-grade connections). Multiple ADSL, even on copper from just one telco, can easily have: 1. different kit terminating PPP sessions 2. different modem/router at your end 3. different interconnect point with the telco 4. in areas with unbundled connections, different dslams. In the case of the UK using BT, putting them on different contention ratios is meant to help too (aaisp mention this, istr). These measures don't always help (e.g. in the case of a telco using radius proxies which are malfunctioning) but probably are worthwhile for some users. The problems I personally have seen the most of are 1 and 2, which are solved quite nicely by natting a connection with a source address of whichever of two providers is functional (or tunnelling to a 3rd point on a highly-reliable network if you want to use real addresses).
