[Gllug] Bank Holiday Monday type question

[Adrian McMenamin]

On Mon, 2005-05-30 at 17:01 +0100, Alain Williams wrote:
> On Mon, May 30, 2005 at 04:52:53PM +0100, Adrian McMenamin wrote:
> > On Mon, 2005-05-30 at 16:36 +0100, Simon Morris wrote:
> > 
> > > 
> > > My guess is that traceroute is trying to resolve the names of the
> > > devices that it comes across and spends some time timing out resolving
> > > the devices on your network.
> > > 
> > > Try running traceroute so it doesn't bother resolving names
> > > 
> > > traceroute -n hostname
> > > 
> > > ~sm
> > no, it's clearly some sort of physical thing...
> > 
> >  1  192.168.62.64  0.554 ms  0.391 ms  0.366 ms
> >  2  172.17.0.1  23.149 ms  22.395 ms  22.712 ms
> >  3  81.1.64.62  23.111 ms  22.677 ms  23.134 ms
> 
> Would I be right in assuming that 172.17.0.1 is the address at the other end of your
> broadband ppp connection ? I find much the same thing ... that most of the time is taken
> getting across the BT collossus network to the ISP, from there things are quite fast.

But what's the physical reason for this? I can see that it takes about
20ms for a packet to cross the continental United States - which is
acceptibly close to c. But why does it takes that long for the packet to
get out across BT's network? Is it really travelling through several
thousand kms of wire and a lot of capacitors, or is it because of some
hidden computational reason (ie a lot of switches storing it and then
resending it?)

-- 
Adrian McMenamin <adrian at mcmen.demon.co.uk>
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