[atlas] Questions about paris traceroute

>> how close an approximation?  chasing ecmp and lag is bad enough without
>> other changes.  folk need reproducible results.
> 
> As far as I know, the actual hashing algorithms used by load balancers
> are in general not known.
> 
> So the only thing paris-traceroute can do is to try to provide
> consistent results for each variation and try to create enough
> difference between variations that it likely that all paths are tried.
> 
> In this context, it doesn't really matter if you try different
> variations in one measurement or run different measurements. In both
> cases some bits will be different. But it not possible to predict in
> advance what is going to happen.
> 
> Worth pointing out in this context (and it is also documented somewhere)
> is that if a probe reboots, the bits it uses for paris-traceroute are
> likely to be different. So consistent results with a single measurement
> are only achieved for as long as a probe doesn't reboot.

a multi-id measurement needs to be closely clusetered in time or changes
in routing or other network events can create ugly and unreproducible
(in the someone else tries the same experiment) results.

don't know about others, but i don't really care about load balancers.
it's ecmp and lag on big pipes.

randy