A Michael F. Schwartz 

T The Great Disconnection? 

I Department of Computer Science, University of Colorado,
Boulder, Colorado 

R Technical Report CU-CS-521-91 

D February 1991 

X Available from
ftp:ftp.cs.colorado.edupubcstechreportsschwartzDisconnection.ps.Z
or
ftp:ftp.cs.colorado.edupubcstechreportsschwartzDisconnection.txt.Z 

X Abstract: "In this paper we present measured data about the
types of sites reachable by upper layer services (such as mail
and "finger") on the global TCPIP Internet.  We analyze changes
in this type of reachability by comparing data from two world
wide measurements, conducted 6 months apart.  Our impetus for
this analysis is to examine the extent to which sites are
reducing their accessibility from the Internet, in response to
increasing security concerns.  We consider upper layer service
connectivity instead of basic IP connectivity because the former
indicates the willingness of organizations to participate in
inter-organizational computing, which will be an important
component of future wide area distributed applications.
Surprisingly, we find that while some sites are disconnecting or
otherwise distancing themselves from the Internet, the vast
majority of sites have retained full or nearly full Internet
connectivity. Moreover, we estimate that the number of sites
accessible via the Internet has grown  approximately 31

 in the past 6 months, significantly outpacing the rate at which
sites are distancing themselves from the Internet.  Our
measurements are broken down by distancing mechanism and
institution typelocation."