How Skype uses the network [was: News item: Blackberry services down worldwide]

Alex Brooks askoorb+nanog at
Sat Oct 15 13:17:54 UTC 2011


On Fri, Oct 14, 2011 at 8:11 PM, Patrick W. Gilmore <patrick at> wrote:
> On Oct 13, 2011, at 7:26 PM, Matthew Kaufman wrote:
> > On 10/13/11 3:30 PM, Patrick W. Gilmore wrote:
> >> In fact, Skype, just as a for instance, is worse on hotel wifi as launching the app on a laptop makes you a middle node for some conversations.
> >
> > Per the Skype IT administrator guide, a Skype node will not become a supernode unless it has a public IP address and meets the memory, bandwidth, and uptime requirements. It will not become a relay node unless it has a public IP address and is directly reachable from the Internet.
> >
> > It is very unlikely that launching the Skype app on a laptop on hotel wi-fi would meet these requirements.
> In the last 5 seconds, without touching Skype or having any active voice or chat sessions open, my computer has had communication with 14 IP addresses.  Here is a sample of some:

For "IT administrators" (which probably qualifies most people on this
list) there is a detailed 26 page guide to how Skype communicates on a
network, when you may become a supernode, and how to configure the
program (including to never become a supernode) using GPO (registry
switches) or XML files at

There is a summary of the Supernodes section (concentrating on how to
stop supernodes happening if you have no control of the client) at

Anybody who might end up with Skyoe clients on their network might
want to give it a gander, as it has some useful info on things like
network impact (along with a lot of stuff that nobody cares about and
you can skip).



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