Dear Gary, Thank you for your reply. Your comment about dupe IP triggered something that I failed to mention: the interface is aliased. It has two IP addresses. IP address a and it has an alias IP address b. I just tested binding mtr to each of these interfaces separately to measure packet loss.
If I use mtr to measure packet loss from saffron (the stricken machine) to cumin (another machine in a different data center) I see the following: saffron (ip address a) -> cumin: packet loss saffron (ip address b) -> cumin: no packet loss cumin -> saffron (ip address a): packet loss cumin -> saffron (ip address b): no packet loss This is consistent from running mtr for 5 minutes straight. This to me shows that the hardware is fine. Using the alias IP address I can run with no packet loss for as long as I like. Hum.... Could it be that my switch does not support IP aliasing? Then why is there packet loss only on one IP and not on both? This is getting weirder and weirder. Kees Jan On 22 Nov 2011, at 22:15, Gary Gatten wrote: > Well, 1% is not good but I've seen worse for sure! Sounds like you tried the > obvious. I would recommend a different IP to rule out a dupe ip; else it > must be NIC related - either hardware or driver. Also, perhaps swap cables > and ports with a working machine and see if the problem follows or stays put. > > ----- Original Message ----- > From: Kees Jan Koster [mailto:kjkos...@gmail.com] > Sent: Tuesday, November 22, 2011 02:33 PM > To: freebsd-questions@freebsd.org <freebsd-questions@freebsd.org> > Subject: Diagnosing packet loss > > Dear All, > > I am stuck with a machine that shows serious packet loss (about 1% of all > traffic is dropped). I tried the obvious (new network cable, different switch > port, different ethernet interface on the machine), but the problems remain. > > Another machine that sits in the same rack and is hooked up to the same > switch shows no such packet loss issues. The problematic machine is a dual > Opteron with FreeBSD 8.2-STABLE from Thu Aug 11 14:05:47 CEST 2011. > > The machine is lightly loaded. A MySQL slave is running, but the machine is > not serving queries. Plus a Munin server process. > > I am at a loss where to start diagnosing this. Can you advise me where to > look? Are there network buffers that may be overflowing? > -- > Kees Jan > > http://java-monitor.com/ > kjkos...@kjkoster.org > +31651838192 > > Change is good. Granted, it is good in retrospect, but change is good. > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org" > > > > > > <font size="1"> > <div style='border:none;border-bottom:double windowtext 2.25pt;padding:0in > 0in 1.0pt 0in'> > </div> > "This email is intended to be reviewed by only the intended recipient > and may contain information that is privileged and/or confidential. > If you are not the intended recipient, you are hereby notified that > any review, use, dissemination, disclosure or copying of this email > and its attachments, if any, is strictly prohibited. If you have > received this email in error, please immediately notify the sender by > return email and delete this email from your system." > </font> > -- Kees Jan http://java-monitor.com/ kjkos...@kjkoster.org +31651838192 I hate unit tests; I much prefer the illusion that there are no errors in my code. -- Hendrik Muller _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"
