What percentage of the Internet Traffic is junk?

[discussing the traffic statistics reported at http://netflow.internet2.edu/ ]

#Note that this is biased by a very significant factor - we're looking here at
#Internet2 traffic *only*, which basically ends up meaning that email isn't seen
#unless both the sender *and* recipient are at one of the 200 or so universities
#that are members, or one of the 50 or so corporate/associate members.

Actually, that understates the relevant population. The traffic seen on Abilene
represents traffic associated with the groups you mentioned, PLUS:

-- all the foreign R&E networks that peer with Internet2 (Canarie, Geant, etc,
   see http://abilene.internet2.edu/peernetworks/international.html )

-- the federal R&E networks that peer with Internet2 (ESNet, DREN, NREN/NISN,
   etc., see: http://abilene.internet2.edu/peernetworks/domestic.html),

-- the 30+ state K12 networks that now connect to Abilene as "sponsored
   educational group participants (SEGPs)," (many of which dwarf their
   affiliated state university systems by a factor of ten or more in size)
   (see http://abilene.internet2.edu/community/segp/list.html )

-- the smaller schools, museums, hospitals, observatories, etc. that are
   connected as "sponsored participants" (see
   http://abilene.internet2.edu/community/sponsored/list.html )

-- event-related traffic associated with things like SC2003 and similar

-- intra-Abilene traffic associated with backbone performance/conformance
   testing, etc.

#For starters, if the sender *or* recipient is at a commercial ISP, it won't
#have been included in those numbers.

That's true for IPv4 unicast trafifc, but Internet2's conditions of use allow
it to carry IP multicast traffic and IPv6 traffic regardless of whether the
source is R&E or commercial.

So yes, it is true that Abilene's traffic doesn't accurately reflect the
activities of the greater Internet, but it does reflect the activity of a
wider base of folks than you might think. What it does not reflect is the
traffic to and from popular destinations such as Google, Yahoo, MSN, CNN,
eBay, etc.