[olug] Network performance analysis

[Rob Townley]

​Care to share how long it has been since the switch was powered down?​

On Sun, Nov 23, 2014 at 10:43 AM, Bill Brush <bbrush at gmail.com> wrote:

> Hey guys,
>
> Thanks for the input.  I have done some wireshark sessions and it
> appears as though there are a number of retransmission packets on my
> tests.  On this test we're just logging into a web page.
> Interestingly enough it doesn't seem slow if I login from the
> internet.  Next week I'm going to do some more packet captures.
>
> I beginning to suspect that my main switch may be having issues.
>
> Bill
>
>
> On Fri, Nov 21, 2014 at 5:08 PM, Matthew G. Marsh
> <olug4mgm at paktronix.com> wrote:
> >
> > Links internally work fine?
> >
> > Links to ISP website work fine?
> >
> > Basically if the "perceived" issue is slowness opening a link, and you
> > suspect networkish issues (DNS, Proxy, Inet, etc) then start local and
> work
> > towards remote.
> >
> > If even local opens up slow then you have either DNS or security software
> > issues.
> >
> > Also - try multiple methods:
> >
> > http://10.1.1.1/index.html  ; if you suspect DNS
> >
> > ftp://ftp.kernel.org  ; if you suspect proxy/security setings
> >
> > and of course you can play around with:
> >
> > smb://10.1.1.1/myfile
> >
> > just for kicks...
> >
> > BTW - better than any speedtest is to download a recent kernel from
> > kernel.org and use a watch... seriously provides a real world latency
> and
> > speed test unless of course you are on the 10G direct fiber link...
> >
> > The other lurking issue is latency. That is best addressed after you rule
> > out DNS/security/proxy/routing issues.
> >
> > in latency some easy tests are:
> >
> > ping -n -v -M time {your local gateway}
> >
> > then move outwards (also good for diagnosing ISP traffic patterns)
> >
> > And of course there is always tracepath if you suspect async routes...
> >
> > HTH.
> >
> >
> > On Thu, 20 Nov 2014, Bill Brush wrote:
> >
> >> Rob I'm painfully (agonizingly) aware of how many variables I'm
> >> dealing with here.
> >>
> >> To go into a little more detail, the raw speed seems fine for the most
> >> part.  We're seeing some traffic spikes on the internet link up to the
> >> limit, but it's rarely sustained.  A speed test at speedtest.net
> >> usually comes back at around 90% of our nominal speed for our link.
> >>
> >> The main "symptom" seems to be a lag in things starting to move.  So
> >> if you click a link it sits there and thinks about it, then moves.
> >> Sometimes this is a few seconds, sometimes it's over a minute.
> >>
> >> I'm going to set up a 30 day trial of Solarwinds bandwidth analysis
> >> pack and hopefully it will show me something.  My forays with
> >> Wireshark have not turned up anything obvious.
> >>
> >>
> >> On Thu, Nov 20, 2014 at 2:22 PM, Rob Townley <rob.townley at gmail.com>
> >> wrote:
> >>>
> >>> Bill,
> >>>
> >>> i feel your pain.
> >>>
> >>> Keep in mind "slowness" can be caused at many layers of the network.
> >>>
> >>> -physical tests to verify Cat6 compliance from (PC) patch cable to wall
> >>> plate thru cable run back to patch panel thru another patch cable (
> >>> network
> >>> switch).  This could be an electrician with a ~$2500.00? Cat6 tester.
> >>> $per
> >>> wall plate
> >>>
> >>> -firmware on NIC / motherboard
> >>>
> >>> -device driver version
> >>>
> >>> -10Mbps half-duplex vs 1000Mbps FullDuplex
> >>>
> >>> -switch
> >>>
> >>> -vPro / IPMI
> >>>
> >>> -IPv6 vs IPv4 issues
> >>>
> >>> -DNS slowness or timing out
> >>>
> >>> -router
> >>>
> >>> -wireless channel (1 ,6, 11)
> >>> On Nov 20, 2014 12:20 PM, "Bill Brush" <bbrush at gmail.com> wrote:
> >>>
> >>>> Hello all.
> >>>>
> >>>> I don't post much, but I've been lurking around here for many years.
> >>>>
> >>>> I'm looking for help investigating complaints that our network is
> >>>> "slow".  I have a rudimentary knowledge of doing packet captures, and
> >>>> the basics, but an in-depth investigation is beyond my current skills.
> >>>>
> >>>> I inherited this network a couple years ago, and I will freely admit
> >>>> that prior to this I had never had to worry about my infrastructure so
> >>>> I have not checked for pre-existing issues.
> >>>>
> >>>> So is anyone in the Omaha area an expert at network analysis?  If it's
> >>>> your day job we can discuss your hourly rates.
> >>>>
> >>>> Thanks!
> >>>> Bill
> >>>> _______________________________________________
> >>>> OLUG mailing list
> >>>> OLUG at olug.org
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> >>>>
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> >
> > --------------------------------------------------
> > Matthew G. Marsh
> > Special Email Addr for OLUG ;-}
> > Phone: (402) 932-7250
> > Email: olug4mgm at paktronix.com
> > WWW:  http://www.paksecured.org
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