Il giorno 27/apr/2015, alle ore 12:10, Paolo Valente <[email protected]> ha scritto:
> > Il giorno 27/apr/2015, alle ore 11:57, Toke Høiland-Jørgensen <[email protected]> > ha scritto: > >> Paolo Valente <[email protected]> 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.) > I am sorry, but I realized that what I said was incomplete. The main cause of my concern is that, from outside the node, we do not know whether a VoIP packet departs ad a given time because the application wants it to be sent at that time or because it has waited in the buffer for a lot of time. Similarly, we do not know how long the VoIP application will wait before getting its incoming packets delivered. Of course, if a bufferbloated state can be measured by other external measurements, then we can infer the problem indirectly. Are there flaws in my above considerations? Thanks, Paolo > 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/ -- Paolo Valente Algogroup Dipartimento di Fisica, Informatica e Matematica Via Campi, 213/B 41125 Modena - Italy homepage: http://algogroup.unimore.it/people/paolo/ _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
