[hobbit] strange result in fping by hobbit and fping by yourstruly
josh at imaginenetworksllc.com
Mon Nov 5 16:35:18 CET 2007
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 <dortsen at gmail.com> 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
> are not resolvable that made this visible?
> Anyway, I now get the correct results, thanks guys.
> > -----Oorspronkelijk bericht-----
> > Van: Henrik Stoerner [mailto:henrik at hswn.dk]
> > Verzonden: vrijdag 2 november 2007 18:07
> > Aan: hobbit at hswn.dk
> > 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
> > To unsubscribe from the hobbit list, send an e-mail to
> > hobbit-unsubscribe at hswn.dk
> To unsubscribe from the hobbit list, send an e-mail to
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