[e2e] Packet reordering in Internet

[Marco Mellia]

Hi Manish,

We did some measurements about TCP anomalies, among which we also 
identify network reordering.
It turned out that reordering is marginal, but sometimes it can be very 
high, e.g., when you hit a strange path.
Details can be found on

M. Mellia, M. Meo, L. Muscariello, D. Rossi
Passive analysis of TCP anomalies
Computer Networks, Vol. 52, No. 14, pp. 2663-2676,

http://www.tlc-networks.polito.it/mellia/papers/comnet08_TCP.pdf

Also, more recent measurements we are doing on different networks show 
that reordering is today limited.
For example, this picture shows the percentage of anomalies identified 
when monitoring our campus network at Politecnico di Torino.
Yellow is network reodering...
http://tstat.tlc.polito.it/cgi-bin/tstat_rrd.cgi?template=normidx&var=tcp_anomalies&dir=rrd_data/Polito/LIVE&bigpic=true&ymax=10&direction=both&ymin=-10

Other measurements (not available on line due to NDA) show similar 
behavior...
For example,
http://tstat.tlc.polito.it/rrd_napa_images/rrd_napa_data.NW-6.tcp_anomalies.normidx.1m.png
shows results from a BRAS aggregating more than 30.000 ASDL customers 
from a ISP ;)
You can see that reordering on those path is less than 1% on average. 
But some single connections can suffer from much higher problems (e.g., 
when going through some load balancing router).

Ciao
Marco

> Hello,
>
> I was wondering if there are measurement studies of Internet traffic
> quantifying the magnitude of packet reordering within a TCP flow. Is
> reordering a common problem for TCP in the current Internet? How about
> the load balancing features in the routers from major vendors : is it
> per flow basis or per packet basis, and if flow based load balancing
> is done, then how is the flow classification is done these routers?
> What could be/are other sources of reordering withing a TCP flow?
>
> Thanks,
> Manish
>
>   


-- 
Ciao,                    /\/\/\rco

+-----------------------------------+
| Marco Mellia - Assistant Professor|
| Skypeid: mgmellia                 |
| Tel: +39-011-564-4173             |
| Cel: +39-331-6714789              |   /"\  .. . . . . . . . . . . . .
| Politecnico di Torino             |   \ /  . ASCII Ribbon Campaign  .
| Corso Duca degli Abruzzi 24       |    X   .- NO HTML/RTF in e-mail .
| Torino - 10129 - Italy            |   / \  .- NO Word docs in e-mail.
| http://www.telematica.polito.it   |        .. . . . . . . . . . . . .
+-----------------------------------+
The box said "Requires Windows 95 or Better." So I installed Linux.