[e2e] VJCC vs. Keshav
detlef.bosau at web.de
Thu Apr 18 05:06:50 PDT 2013
Am 18.04.2013 11:45, schrieb Jon Crowcroft:
> I think the point i was trying to convey was that
> packet pair (and packet train) and fair queuing (and other more active
> queue management algorithms) have seen evaluation by
> many people using many tools (including measurement as well as
Yes. And being short and frankly: When it comes to mobile networks, I
don't believe a word of the packet-pair and packet-train stuff.
Even for the radio interface, it simply doesn't make sense to talk about
an "average bit rate" in this case, when this is associated with both, a
reasonable hight throughput and a reasonably low block corruption rate.
However, you can well implement packet pair and packet train stuff and
observe some funny numbers in real networks. That's nice, other people
collect stamps..... .
But when we put those numbers in c-code and derive "serialization
delays" from them, the result is simply fictional.
It took me years to learn this lessen and perhaps, it was one of my most
difficult lessons ever.
So, the question is: What is the reality, which really corresponds to
When I started my work in a project called COMCAR 13 years ago, and I
talked about QoS, the EE colleagues ridiculed at me "You dealt with
wired networks up to now, right?" and a colleague from CE simply
answered my question concerning bit error rates simply and harsh: "There
is nothing like bit error rates."
What I learnt meanwhile: Both were right.
And as there is no such thing like a "bit error rate", there is no such
thing like a (more or less or at least quasi more or less stationary)
And therefore, all this packet pair stuff and packet train stuff is
interesting stuff inspired by the behaviour of wired networks, but with
respect to mobile networks, we talk about pure fiction and artefacts here.
70565 Stuttgart Tel.: +49 711 5208031
mobile: +49 172 6819937
detlef.bosau at web.de http://www.detlef-bosau.de
More information about the end2end-interest