FastPath - worth it?

[KerbMav]

By accepting the loss of some kind of error correction the ISP can activate FastPath to reduce latency.

How critical is the possible packet loss etc. without interleaving? What might happen?

[Renegrade]

Er, FastPath? Do you mean DSL fast channel?

If yes, then the answer is, 'it depends on your line'. I had a handful of errors on my old line on occasion (the building I lived in back then was an expensive dive), and the LEC would change it over to interleaved. I'd call them up and escalate four or five times, and have it switched back to fast channel. Interleave puts on a great deal of latency even when it's doing nothing, and when I had it off, the handful of errors didn't cause any significant problem, vs. a fairly massive spike in latency with it on.

If your line has a lot of errors though, you might spend more time re-transmitting at higher levels of the protocol stack, and it may not be worth it to force a change back to fast channel. (the higher levels generally ALSO have error detection/correction)

Note that if your line is kinda thin on the margins, you might get better responsiveness by going to a slower profile.

And of course, whether or not any sort of tradeoff like this is worthwhile depends on usage. If bulk transfers are your main thing, fast channel isn't going to help much. On the other hand, if you do online gaming, especially with twitchy games, shaving 20-30ms off your ping might be worthwhile...

(the massive escalation is required as the telcos around here are usually using script-readers overseas, and if you escalate there, you speak to a senior script-reader, and then to the guy who manages script readers before being transferred to something local, in which case you have to escalate past THAT script-reader to speak to someone on the test board)