strange result in fping by hobbit and fping by yourstruly

You may have had ap1.foo.com and ap2.foobar.com (two different domain, one
of which is not registered).

On 11/5/07, Dennis Ortsen <user-8b22a8e3a886@xymon.invalid> wrote:

The testping tag solved my problem.

Strange however that with that large number of access points I didn't have
the same issue. Perhaps it's just the additional number of IP-addresses
that
are not resolvable that made this visible?

Anyway, I now get the correct results, thanks guys.

Br.

Dennis

-----Oorspronkelijk bericht-----
Van: Henrik Stoerner [mailto:user-ce4a2c883f75@xymon.invalid]
Verzonden: vrijdag 2 november 2007 18:07
Aan: user-ae9b8668bcde@xymon.invalid
Onderwerp: Re: [hobbit] strange result in fping by hobbit and
fping by yourstruly

On Fri, Nov 02, 2007 at 01:46:44PM +0100, Dennis Ortsen wrote:

I only do a conn test on an ip-address. I use the full path
to fping
in hobbitserver.cfg, without any extra parameters. When
hobbit starts
testing the connection, only 14 terminals respond to a
ping, but when
I execute a fping myself (as the hobbit user) in a shell to
the same
amount of terminals, I get a totally different result,
instead of 14
responding terminals, I get 95 responding terminals with
fping! It's
not just a lucky shot, I can keep on trying these
terminals, the huge
difference remains whether I fping them myself or when
hobbit fpings them.

I'm running hobbit 4.2.0. According to bbtest I have 806 hosts that
are pinged, that takes about 26 seconds to complete. To
complete all
tests (954), it takes about 47 seconds.

Does anyone have a clue why specifically these terminals
have such a
difference in hobbit ping and a ping performed by myself?

What error does the failed ping tests show - DNS error, or
just ping failure ? If it's DNS errors, use the "testip" tag
to avoid doing DNS lookups - I understand from the other
mails in the thread that these systems are not in the DNS.

I suspect it might be an issue with the number of tests
running simultaneously. ICMP packets have lower priority in
most network equipment, and is therefore the first packets to
be discarded when there is a lot of traffic on the network.
Since you're referring to "terminals" they might not have a
lot of memory for network buffers and therefore they might
drop packets more often than "real" computers.

There is also a possibility that the number of hosts tested
is overflowing the ARP cache table on the Hobbit server,
which can lead to packets being lost.

I'd suggest starting with some extra options for bbtest-net (in
hobbitlaunch.cfg): Add --concurrency=32 to the bbtest-net
command, and change the FPING setting in hobbitserver.cfg to
FPING="fping -i150", this will increase the time fping waits
between sending packets from 25 ms to 150 ms, so there is
less ICMP traffic on the network.

You can replicate how Hobbit performs the ping test by
putting the IP's of all your hosts into a text file (one IP
per line), then run
    fping -Ae </tmp/IPlist.txt


Regards,
Henrik

-- 
Josh Luthman
Office: XXX-XXX-XXXX
Direct: XXX-XXX-XXXX
XXXX Wayne St
Suite XXXX
Troy, OH XXXXX

Those who don't understand UNIX are condemned to reinvent it, poorly.
--- Henry Spencer