[wellylug] Re: Can't access linux conf site

[Jamie Baddeley]

On Sun, 2005-11-13 at 20:53 +1300, Mark Foster wrote:
> > did the ping -s 1500.
> >
> > I found that the address 203.63.130.250 drops anything over 1400.
> > Anything below that has around 20% packet loss.
> >
> > This address is just before the common address.
> >
> >
> > I'll do some more playing in the morning when I'm more awake. ;-)
> >
> 
> Jethro - excellent, You have identified the problem or at least the 
> location of it.
> 
> Step 1: Adjust your MTU up to the highest MTU that works - 1400 or 1399 or 
> whatever.
> 
> Step 2: Provide the test information to Ihug tech support and ask them to 
> escalate to their international carrier.  This is an ISP level issue that 
> obviously exists in the upstreams.  Likely that other people in your IP 
> netblock have similar issues...
> 
> Mark.
> 
> Oh, Step 3: Once the situation is restored put your MTU back to the 
> default. MTU adjustment is usually a 'bad thing' (tm) unless its really, 
> really necessary.
> 

My guess on all of this is there's some asymmetric routing that's hiding
the cause. I tried the same test on the forward path and it seems ok. If
you can, get the LCA guys to send you a traceroute from their host
towards your host. As a result, you can supply a list of return path
networks to your ISP, then you'll speed up the process if you want it
to.

jamie