[olug] Network performance analysis

[Bill Brush]

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
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>>>>
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>
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