[tahoe-dev] Question about convergence keys

[Drew Perttula]

Jeremy Fitzhardinge wrote:
> More awareness of network topology.  If I have a local lan of machines 
> which are participating in a grid, I'd like them to prefer to replicate 
> to each other, and have a single, more connected, node responsible to 
> sync off-site.  I had two ideas for using zeroconf/bonjour/avahi:
> 
>    1. Use it to discover the correct upload helper for a given network. 
>       No one upload helper is necessarily correct for a mobile node
>       which moves around and connects to different networks.
>    2. Use it to find other nodes on the same lan, so that they can be
>       used for preferential communication.  This would be particularly
>       useful if the network is natted and doesn't give hosts externally
>       routable addresses; they would still be able to locally discover
>       each other.

Bringing in stuff like avahi sounds like a really heavyweight solution 
that might not even pay off. In more exotic networks, VPNs might make 
faraway machines look local, or nearby machines might be on opposite 
sides of a router that doesn't conduct avahi. (I think I have both of 
those effects at my house :)

Why would you want anything other than "prefer to replicate to hosts 
that are currently fast to talk to"? If we're looking for 10 hosts on 
the list of 50, instead of picking at random, we might pick the ones 
with low ping times. Of course that will have side effects regarding how 
fast the nodes fill their disks, etc.