- Ping query
- Posted by bof on July 22nd, 2003
If, over the Internet, I ping a destination that's not responding then,
as expected, I get "destination timed out", if that destination starts
responding the message changes to "reply from w.x.y.z", once it closes
down again the message changes to "reply from w.x.y.z TTL expired in
transit" after an hour or two this drops back to "destination timed out"
Just curious as to why "TTL expired" appears for an hour or so before
"destination timed out" returns.
Any advice?
--
bof at bof dot me dot uk
- Posted by John Olechnowicz on July 22nd, 2003
"bof" <nothingread@hotmail.com> wrote in message
news
QmLyWBUIYH$Ew5v@invalid.domain...
And this is the guy that pulled me up on one spelling mistake!
Advice... Yes! Get someone to check your punctuation.
- Posted by bof on July 22nd, 2003
In message <8hgTa.51081$xd5.2930037@stones.force9.net>, John Olechnowicz
<johno@hangar18.co.uk> writes
Ooops didn't realise you'd taken it that way, I certainly didn't intend
it as a spelling pullup it was only posted as light hearted banter, the
spelling just seemed funny juxtaposed against your concern at having got
the comms theory wrong, when you were right.
Anyone recommend email with built in grammar checker?
Any advice on the ping responses?
--
bof at bof dot me dot uk
- Posted by Martin Cooper on July 22nd, 2003
bof <nothingread@hotmail.com> wrote:
<snip>
Hi,
only a guess, but most of the internet runs on routing protocols that
dynamically reconfigure. If someone switches of their ADSL modem / router,
then I suspect that the route is cached for a while by the various routers
within the BT network.
When this happens, sometimes you get routing loops within the BT network, so
if you try a traceroute instead of a ping, you will probably find the
packets get bounced around between two or three routers repeatedly.
Eventually, the TTL will reach a value of 0, and you get the 'TTL expired'
error.
If you leave it for an hour, then the routers will have forgotten that they
knew the route to the network that has been disconnected, so the packets
will bounce back with the 'destination timed out' error.
Although the above is a bit of a guess, I have frequently seen these routing
loops within the BT network when a connection goes offline.
--
Martin
- Posted by Andrew Norman on July 22nd, 2003
On Tue, 22 Jul 2003 21:27:50 +0100, bof <nothingread@hotmail.com>
wrote:
Your grammar isn't that bad, especially when compared to some people
around here. You just need to insert a full stop occasionally.
A five line paragraph with one sentence and six commas is very
difficult to read...
--
Andy Norman andy@norman.cx
http://www.norman.cx/
- Posted by Robert Woolley on July 22nd, 2003
On Tue, 22 Jul 2003 21:42:25 +0100, Martin Cooper
<usenet@martinc.me.uk> wrote:
Yes, the well known 'stale route' problem.
Rob.
--
rob at robertwoolley dot co dot uk
