Re: [Bloat] Detecting bufferbloat from outside a node

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

Il giorno 27/apr/2015, alle ore 11:57, Toke Høiland-Jørgensen <toke@toke.dk> ha scritto:

> Paolo Valente <paolo.valente@unimore.it> writes:
> 
>> 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).
> 
> Sure. Just measure the timing when the network is unloaded and compare
> it to when it is loaded to capacity. We do that all the time.
> 
> The details of course depend on what you define by a 'node', what role
> it plays in the network (does it forward or originate packets?), and
> what control you have over the traffic flowing through it. :)
> 

Let us consider, for example, a host with a VoIP call and a large-file transfer in progress. My concern is: from inside the host, we can measure the delays experienced by the VoIP application, but, form outside, how can we detect that the application is experiencing a high latency, or, indirectly, that there is bufferbloat and hence that the application is likely to be experiencing a high latency? (Of course, I am also about to read the documents suggested by Neil.)

Thanks,
Paolo

> -Toke


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