[NTLUG:Discuss] Network 'passthru' viewer

[Gilbert Morrow]

DSLreports will do a line test and suggest the best MTU if you would like to
check your line and see what they say just for kicks.

Linux free is always better.
On Jan 26, 2011 2:50 PM, "David Simmons" <dave at dgnal.net> wrote:
> Just a 'report back'....since my issues were intermittent with FIOS, I'll
> have to use/try it for a few days - but I will say, saying the MTU to 1400
> has really made the network / internet noticeably peppier!
>
> Thanks - great insight and suggestion,
>
> -dave
>
> On Wed, Jan 26, 2011 at 1:20 PM, David Simmons <dave at dgnal.net> wrote:
>
>> Preston - wow...that's some great intel to try...thanks! - dave
>>
>>
>> On Wed, Jan 26, 2011 at 11:49 AM, Preston Hagar <prestonh at gmail.com
>wrote:
>>
>>> On Mon, Jan 17, 2011 at 9:44 PM, David Simmons <dave at dgnal.net> wrote:
>>> > Guys/Gals,
>>> >
>>> > Help me to understand what software/hardware is necessary to compete
the
>>> > following task.
>>> >
>>> > I have Verizon FIOS...recently the quality of service has been bad
>>> (meaning
>>> > I try to go to a website and it times out)..but at times of the it
works
>>> > great. Even when I believe it's not working well (as indicated by
>>> trying to
>>> > log into the local Verizon router and it taking ALONG time to respond)
I
>>> see
>>> > the lights flickering. SO, I think to myself, "Who's fault is this?"
>>> Do I
>>> > have a hacked machine that's spitting out spam/junk? Is it my side or
>>> their
>>> > side?
>>> >
>>> > So I figure if I had a system/laptop/whatever with two network cards -
I
>>> > could setup network pass-through or bridging so that I could
>>> > see/categorize all of the packets that are flowing through (seeing
their
>>> > source & destination IP address.....and having some sense of the
content
>>> of
>>> > the packet - beit email, web, etc, etc).
>>> >
>>> > I was originally thinking an IPCop setup...but realized that I don't
>>> want
>>> > ANY firewalling going on...just want the data to flow through and
>>> > watch/sniff/see what it is?
>>> >
>>> > Any help / ideas / webpages would be appreciated,
>>> >
>>> > -dave
>>> >
>>>
>>> At the company I work for, we have Verizon "Business" Fios on a 35
>>> down / 35 up plan. A few months back, seemingly random (we figured
>>> out later they weren't random) webpages seemed to load, time out or
>>> have other weird issues. We were, at the time, using a custom built
>>> FreeBSD router that had a Cat 5 run from the ONT to the router. We
>>> figured maybe something was wrong with the router, or DNS or our LAN
>>> and spent forever trying to find the answer. Finally, we came across
>>> it, MTU.
>>>
>>> Apparently on the peers that our Verizon FIOS hops through, there is a
>>> MTU black hole. The peer with the black hole was part of the route
>>> for a lot of major sites, but the most reliable (to break that is)
>>> that I found were provantage.com, newegg.com, and microsoft.com. We
>>> found empirically (we ran traceroutes and pings, gradually increasing
>>> the packet size until it it would be dropped) that by setting the MTU
>>> of our router and machines to 1400 (instead of the default 1500) the
>>> issues went away. To confirm it wasn't faulty hardware anywhere under
>>> our control, we tried using our Logix T1 connection and would have no
>>> issues accessing any site (including the 3 mentioned) with the same
>>> router and same hardware. We also tried using Verizon's Actiontec
>>> router and it experienced the same issues as our FreeBSD router. We
>>> tried talking to tech support and generally just got "we'll look into
>>> it, or everything looks fine on our end". In the end, we just set the
>>> MTU to 1400 for everything and gave up trying to get Verizon to fix
>>> it. We haven't noticed any major decrease in performance using a
>>> smaller max packet size and now all sites load quickly and normally.
>>>
>>> Anyway, if you experience issues with time outs again, you might try
>>> lowering the MTU of your machine and router to 1400 (or somewhere
>>> along those lines) and see if that helps.
>>>
>>> For Linux machines, the command to change the MTU is
>>>
>>> ifconfig <network device> mtu 1400
>>>
>>> where <network device> is eth0 or whatever your network card is named.
>>> Where to configure it permanatly depends on your distro.
>>>
>>> If it doesn't help or make any difference, you can always set it back
>>> to 1500 and no harm done.
>>>
>>> Preston
>>>
>>> _______________________________________________
>>> http://www.ntlug.org/mailman/listinfo/discuss
>>>
>>
>>
>>
>> --
>> Those with sight believe what's believable. Those with vision know what's
>> unbelievable.
>>
>
>
>
> --
> Those with sight believe what's believable. Those with vision know what's
> unbelievable.
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