[Gllug] Bank Holiday Monday type question

[Ian Norton]

On Mon, May 30, 2005 at 05:12:12PM +0100, Adrian McMenamin wrote:
> 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?)

I would say its because that when it comes from you, it has to undergo lots of
hops in ATM which will be invisible to you, also, the 
routing from when it arrives at your isp and goes elseware is down to your isp,
thier servers may be overloaded when it comes to re-assembling your ip packets
from atm cells

i may have the wrong end of the stick tho
 

-- 
Ian Norton-Badrul

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