Hardcoded limit on the number of meta-connections

[Etienne Dechamps]

On 07/08/2014 12:13 PM, Guus Sliepen wrote:
> On Sun, Jul 06, 2014 at 09:27:37AM +0200, zorun wrote:
>
>> I was quite surprised to see commmit 332b55d4 ("Change AutoConnect
>> from int to bool").  Is there experimental evidence supporting 3 as
>> the hardcoded maximum number of meta-connections?
>
> Yes. Note that it is not a maximum number, but rather the goal to have
> that number of meta-connections. Simulations show that 3
> meta-connections per node results in a robust graph where the removal of
> any one node will not cause others to be disconnected from the VPN. So 3
> is already providing redundancy, more meta-connections per node will
> just result in more overhead. Setting it lower might result in graphs
> where not all nodes can reach each other.

I'm not sure I agree. That's only true if you can establish a new 
metaconnection immediately after you lost one. In practice that's not 
always the case (e.g. nodes behind NAT, etc.) so it would take an 
extended amount of time to find a node you can actually establish a 
metaconnection to. This means you can very well get into a situation 
where you would lose most metaconnections before you can re-establish 
some of them.

-- 
Etienne Dechamps