"Does TCP Need an Overhaul?" (internetevolution, via slashdot)

Steven M. Bellovin smb at cs.columbia.edu
Sat Apr 5 09:54:27 UTC 2008

On Sat, 5 Apr 2008 01:02:24 -0400
"Christopher Morrow" <morrowc.lists at gmail.com> wrote:

> On Fri, Apr 4, 2008 at 9:51 PM, Paul Vixie <paul at vix.com> wrote:
> >  (i'd hate to think that everybody would have to buy
> > roberts' (anagran's) Fast Flow Technology at every node of their
> > network to make this work.  that doesn't sound "inexpensive" to me.
> I suppose he could try to sell it... and people with larger networks
> could see if keeping state on a few million active flows per device is
> 'expensive' or 'inexpensive'. Perhaps it's less expensive than it
> seems as though it would.
> Oh, will this be in linecard RAM? main-cpu-RAM? calculated on
> ASIC/port or overall for the whole box/system? How about deconflicting
> overlapping ip-space (darn that mpls!!!) what about asymmetric flows?
> I had thought the flow-routing thing was a dead end subject long ago?
And you can't get high speeds with Ethernet; you get too many
collisions.  Besides, it doesn't have any fairness properties.
Clearly, you need token ring.

Oh yeah, they fixed those.

I have no idea if it's economically feasible or not -- technology and
costs change, and just because something wasn't possible 5 years ago
doesn't mean it isn't possible today.

It does strike me that any such scheme would be implemented on access
routers, not backbone routers, for lots of good and sufficient
reasons.  That alone makes it more feasible.

I also note that many people are using NetFlow, which shares some of
the same properties as this scheme.

As for the need -- well, it does deal with the BitTorrent problem,
assuming that that is indeed a problem.

Bottom line: I have no idea if it makes any economic sense, but I'm not
willing to rule it out without analysis.

		--Steve Bellovin, http://www.cs.columbia.edu/~smb

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