@several of you
Here's some info on how it works, straight from the mouth of someone who worked there for a while last year:
"Would be great if you could use cable on one router and ADSL on the other" - I don't think there's any technical obstacle to this. I don't know what's available in product form though.
"The problems start *because* you have two different WAN (ADSL) connections, and therefore two different IP addresses" - Sharedband handles this by giving you a completely new IP address from a pool that they own themselves. The two separate Internet-visible IP addresses of your two ADSL lines aren't used to communicate with the sites you visit. As a result your publically visible IP address stays the same no matter which of the bonded lines your packets happened to travel through.
"Several UK ADSL ISPs support this", "Unless this is something other than multilink PPP" - It's not multilink PPP, it works at the IP level. The bit that's new is the ability to bond together DSL lines _from different providers_ which as far as I know isn't possible with multilink PPP.
"all packets first have to travel to a 3rd party host before being reassembled and going on to their final destination" - correct, this is exactly how it works. The latency impact is unnoticably small (this isn't speculation, I measured it) because the 3rd party hosts are located in ISP data centres with fast, low-latency connections to high speed backbone pipes. The "single point of failure" issue here is addressed by integration with BGP; if any of the "3rd party hosts" goes down, another can take over by re-routing the affected block of customer IP addresses.
Biting the hand that feeds IT
