Re: [Bloat] Detecting bufferbloat from outside a node

[Paolo Valente <paolo.valente@unimore.it>]

Thanks for the pointers. As for the epistemological implications of to my concerns, I must admit that I find them a little bit frightening :)

After browsing some of the presentations, the relevant component for my problem seems to be the variability V. However, it is not clear to me how I can measure or infer it in my situation, i.e., if I cannot:
1) have any feedback on the user experience;
2) measure the time that elapses between when a time-sensitive application puts a message in a socket and when that message is actually sent by the node in a packet;
3) in the opposite direction, measure the time that elapses between when a packet arrives to the node and when the application receives the message contained in the packet.

On which documents should I concentrate more to better understand this point?

Thanks,
Paolo
 
Il giorno 27/apr/2015, alle ore 11:54, Neil Davies <neil.davies@pnsol.com> ha scritto:

> Paolo
> 
> Yes, it is - there is a whole methodology for detecting this and associated algebra for manipulation. It has been used at CERN, in various telcos and in various large scale, real time distributed systems to relate end user outcomes to the delay/loss characteristics of the network.
> 
> Take a look at http://www.pnsol.com/publications.html, you may find http://www.pnsol.com/public/PP-PNS-2009-02.pdf as a good starting point.
> 
> Neil
> 
> On 27 Apr 2015, at 10:48, Paolo Valente <paolo.valente@unimore.it> wrote:
> 
>> Hi,
>> a network-monitoring company got curious about bufferbloat issues and asked me to investigate a little bit the following issue (quite interesting in my opinion). Is it possible to detect, from outside a node, if the node is bufferbloated? In particular, the only action allowed would be to observe the packets entering and leaving the node (plus, of course, their timing).
>> 
>> If such a general problem is to hard or impossible to solve, do you think it is still possible at least to understand, for some type of application, if the application is experiencing a high latency because of bloated buffers inside the node? (As above, by just observing packet flows from outside the node.)
>> 
>> Thanks,
>> Paolo
>> 
>> _______________________________________________
>> Bloat mailing list
>> Bloat@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/bloat
> 


--
Paolo Valente                                                 
Algogroup
Dipartimento di Fisica, Informatica e Matematica		
Via Campi, 213/B
41125 Modena - Italy        				  
homepage:  http://algogroup.unimore.it/people/paolo/