[Gllug] Demon Service (ha!)

[Nix]

On Tue, 27 Nov 2001, will at hellacool.co.uk uttered the following:
> Andy Loates wrote:
> 
>> Is it me, or is Demon's normally reliable service being decidedly pants at
>> the moment.
>> No e.mail service over the weekend, Now I cant even PING their Nameservers.

I had mail delivered from punt-11 and -21 throughout the weekend, and no
routing failures at all; it's probably your setup(TM). Now last
Wednesday was a different matter :( (and a first; I've never known email
to be down for everyone before. Sticky punts, yes, but that's somewhat
different.)

> Their mail servers are available about 2/3 of the time it seems.  A

?!! *boggle*

Inbound mail kicks mail down to me every ten minutes without fail.
Outbound I don't know, because I've never used their

> few traceroutes seem to show sporadic timeouts at their mailservers

Another person misunderstanding how traceroute works :(

Traceroute cannot show timeouts; traceroute cannot reliably show packet
routes, as they can change while the traceroute is occurring; traceroute
is merely indicative.

In particular, sporadic timeouts at a router merely means that the
router is (sensibly) throttling the relatively expensive operation of
generating ICMP TTL Exceeded packets in favour of routing packets. All
decent routers do this. (Kieran, if I'm talking balls and some do not
do this, speak now!)

(And likewise for all points beyond such routers, too; ICMP TTL Exceeded
messages are unreliable and can be dropped on the floor without notice.)

-- 
`The situation is completely under control. All of them were killed.'
     --- Alim Razim, for the Northern Alliance, demonstrating fine
         command of traditional Afghan prisoner control techniques.

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