Common operational misconceptions

Masataka Ohta mohta at necom830.hpcl.titech.ac.jp
Fri Feb 17 00:24:42 CST 2012


Valdis.Kletnieks at vt.edu wrote:

> No, you said specifcially that it can be restored by end system*S*
> plural.

Yes, end to end connectivity is restored.

However, that end to end connectivity is restored does not
mean your boxes can use 131.112.32.132 nor port 49734.

> Yes, I can get one box listening.  Now tell me how to get
> the second and third boxes listening on the same port.

Perhaps, you misunderstand how end systems behind NAT
must interact with UPnP or something like that to be
able to restore the end to end connectivity.

End systems behind UPnP boxes are allocated disjoint
sets of global port numbers, only among which, end
systems can use as their global port numbers.

End systems can obtain information on port numbers
they can use through UPnP or something like that.

Thus, there is no port number collision at the global
side of the UPnP box.

Similar mechanism is described in draft-ohta-e2e-nat-00.txt

						Masataka Ohta



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