[atlas] Flow-id of built-in traceroute measurement

Hi,

On 2016/04/05 20:53 , Wenqin SHAO wrote:
> I have some questions concerning the flow-id of built-in traceroute measurements and are seeking for your help.
> 
> As many of you may have already noticed, the flow-id of the built-in traceroute measurement periodically varies form 0 to 15, in a circular manner.
> With this behaviour, it is supposed to reveal the diversity of underlying IP paths.
> 
> In the case that there are more than 16 unique IP paths between a source and destination pair, could this scheme reveal all of these IP paths?
> If it can, which leads to more than one IP paths per flow-id? Is it normal, from a load balancer point of view?
> If it can not, then why not a wider range of flow-id (more nuances in header hash results), say [0, 63]? Is it related to common realisation of load balancer?

Basically, the wider the range, the longer you have to wait for two
traceroute results that take the same path.

Of course, if you want to investigate one particular path, you can just
schedule your own measurement with different parameters.

I have not seen any analysis that estimates what percentage of source,
destinations pairs would have more than 16 different paths. If that
percentage is significant, then it's worth considering raising the value.

Philip