Flow Based Routing/Switching (Was: "Does TCP Need an Overhaul?" (internetevolution, via slashdot))

michael.dillon at bt.com michael.dillon at bt.com
Sat Apr 5 21:59:14 UTC 2008

> The flows are in those boxes, but only for stats purposes 
> exported with NetFlow/IPFIX/sFlow/etc. Apparently it was not 
> as fast as they liked it to be and there where other issues. 
> Thus what exactly is new here in his boxes that has not been 
> tried and failed before?

Roberts is selling a product to put in at the edge of your
WAN to solve packet loss problems in the core network. Since
most ISPs don't have packet loss problems in the core, but
most enterprise networks *DO* have problems in the core, I think
that Roberts is selling a box with less magic, and more science
behind what it does. People seem to be assuming that Roberts
is trying to put these boxes in the biggest ISP networks which
does not appear to be the case. I expect that he is smart enough
to realize that there are too many flows in such networks. On
the other hand, Enterprise WANs are small enough to feasibly 
implement flow discards, yet big enough to be pushing the 
envelope of the skill levels of enterprise networking people.

In addition Enterprise WANs can live with the curse of QoS, i.e. that
you have to punish some network users when you implement QoS. In the
Enterprise, this is acceptable because not all users have the same
cost/benefit. If flow switching lets them sweat their network assets
harder, then they will be happy.

--Michael Dillon

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