[nmglug] ping -p ff , bad checksums, isp 5GHz wireless, lost packets?

[Nick Frost]

On Jan 9, 2011, at 4:20 PM, a wrote:

> As you can see the md5sum resolve Thanks for the providing the test
> files and usage clarification.

Anthony;

Sure. It's encouraging that the checksums match (at least as far as  
your Internet connection is concerned). I think, given what you posted  
previously (ping tests) and that the checksums match, that I see  
little evidence (at least so far) of an Internet connection problem;

 >Bad checksum,lost packets?

 >Specifics;
 >ISP supplied internet connect this area 5GHz wireless.
 >Repeated, distro download, bad checksums,
 > Ubuntu update manager Kernel errors notice....

More likely (than packet loss or corruption on your 5 Ghz wireless  
link) would be;

-  a problem with your hard disk (might be worth booting from CD and  
running a surface scan or the badblocks program within Linux)
- an upgrade or update problem (software) generating the errors.   
(Cumulative problems from previous upgrades, updates, etc.)

As for why you don't get a good checksum from your home connection in  
contrast to the connections in town as you described here;

 >I have not been able to get a good checksum(8-10
 >tries over several days) for Ubuntu Distro server with laptop wired to
 >router, from my home location through the ISP 5GHz wireless internet
 >connect.
 >While using that same laptop,same server address request, similarly
 >wired connect at ISP  office resulted in good checksum.
 >Santa Fe baking Co.same laptop and reflector wireless 801.11 connect,
 >good checksum.

it could be that you are accessing a different update server (mirror)  
from  your ISP 5Ghz location than the SF Baking Company, a given  
hostname may resolve to more than one IP. I think synaptic usually  
tries to find the closest mirror.  In my experience (having done a few  
long range 2.4 Ghz wireless shots with Tranzeo transceivers and/or  
parabolic antennas) a problem with long range wireless Ethernet,  
particularly at 5 Ghz is that it's susceptible to weather (snow, rain,  
etc)  So one might get dropped packets one day and not another.  You  
can sometimes test for these sorts of 802.11 framing-errors using ping  
but gradually incrementing the packet size (ping -s).

If your machine will not allow normal updates with the specified  
kernel version, then it may be you have something of a broken  
installation.   On that note when I download a 10.04 ISO I usually  
checksum the ISO before burning it to a CD or DVD and that way one  
knows one has a good install (if the underlying hard disk is free of  
errors).  IMHO, since installing and updating an OS is a fair bit of  
work it often merits running Seatools, Western Digital Diagnostics,  
Hitachi Drive Fitness Test on the hard drive or some tool like that  
prior to re-installing.

You could also try cleaning out your cache with apt-get clean and/or  
doing apt-get install netselect to make sure your list of mirrors is  
optimal;

http://www.debian.org/doc/manuals/apt-howto/ch-basico.en.html

If you can't boot except with older kernels, you might check your C  
libraries (libc) and make sure they are current, long with GCC  
matching that version of Ubuntu.   You could also boot from CD and  
generate a new initrd based upon the newer kernel and see if that gets  
you anywhere in terms of fixing the issue whereby you can't use a  
current kernel.

But, from what you have written here below;

 >I have been spurred on recently,toward seeking a solution,after  
noticing
 >the update manager included kernel ending with .22 and apparently
 >installed along with error notation?.After that kernel .22 install?,
 >I could not longer boot except by using kernel ending .16 still  
existing
 >as a boot option.More recently, when doing a new program install, that
 >program did an automatic kernel upgrade to .22 as part of the install.
 >Again I could not boot except using kernel ending .14 another boot
 >option,most apparently,this perspective is  technically limited.

 >Eventually I did a new install,ubuntu 10.10,from disk which noted
 >errors,possible errors from the internet updates.I did not do a  
checksum
 >on the CD from QSDisc,

I would say that while I think it's worth trying some more things  
before suggesting you reinstall your system (a suggestion I don't like  
making, given the effort involved) I would speculate you might need to  
start with a good foundation, that being a system with fully-tested  
disk(s), fully tested memory (Memtest86) and a layout of Ubuntu that  
is know to be error free by virtue of the .iso from which the CD was  
made matching that of the published .iso md5 signature.

At one of my jobs I use Ubuntu 10.04 (Lucid) on a Dell Optiplex 960,  
it was installed with 9.10 (Karmic) or possibly 9.04 (Jaunty)...and in  
1.5 years or so I have not had any issues with updates really (save  
some transient error on two occasions); the system runs fine and the  
updates just work (but I make sure to do them weekly at a minimum).

Good luck,

-Nick

---------------------------------------
Nicholas S. Frost
7 Avenida Vista Grande #325
Santa Fe, NM  87508
nickf at frostitute.com
----------------------------------------

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