[NTLUG:Discuss] Network 'passthru' viewer

[Gilbert Morrow]

On Wed, Jan 26, 2011 at 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.
> >
>
> MTU optimization <http://www.dslreports.com/faq/695> try this , seems 1472
> + 28 is for most .
>
> --
> Those with sight believe what's believable. Those with vision know what's
> unbelievable.
> _______________________________________________
> http://www.ntlug.org/mailman/listinfo/discuss
>



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