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Zip file corruption...

Hello all!

Does anyone have any idea what can cause zip files to become corrupted through transfer? I cannot download zips that contain other zips. Or any extractable that contains other extractables, they always corrupted the compressed zip. all other files in the zip file extracts fine, but if the zip or exe or rar, cointains another extractable, that file will be corrupt! It only happens in one location and I can reproduce it everytime, Especiialy on larger files.

The environment is as follows...

3745 router

2950 48port FE gb switch

3508 gb swicth

I have tried from mulitple computers and from multiple os's and from multiple sources, all different vendors and co's,, veritas etc. I have spoken with my Datacenter who is also our isp and we ran a nights worth of packet captures from my pc and they cant see anything out of the ordinary. We are running 2 vlans that the router is handling, as well as the swictehs trunking, but I cant see how that can be a problem. I was reading online about baby giants and MTU size etc. Our MTU on all devices is the default 1500.

any thoughts?



  • Other Network Infrastructure Subjects
Cisco Employee

Re: Zip file corruption...

In my experience, if the network is indeed the problem, it generaly is result of data corruption that occurs at a Layer 3 rewrite boundary. Since, layer 2 rewrites are done at Layer 3 boundaries, the problem could occur there. If the problem was happening at Layer 2, the switches in the network would detect the invalid CRC and drop the frame.

Is this problem actually occuring over IP? IP does have a Layer 3 checksum to prevent from occuring what I mentioned.

MTU should not be an issue if it configured correctly end-to-end.

To troubleshoot, create an extremely large file and place it on your local computer. Make a copy of this file. Send the file to remote computer across the network. Retrieve the file from the remote computer and compare the file against the original file. I would use the MS windows fc command to do the comparison since it does comparison at the binary level. If the files do not compare exactly, then something in the network may be corrupting the file.

Re: Zip file corruption...

I beleive this test will prove this is not a network problem.

I'd try to check if your unzip program works correctly or if your PC doesn't have a problem with lack of memory or something like that.




Re: Zip file corruption...

I have tried to download files from a few different computers in the company, not lessthan 256mb of RAM, mine is a 2ghz laptop with 512, as is a co-workers laptop, but his is 1ghz cpu.Win2k pro or Winxp pro. I have tried to rule out as much as I can. Here is the wierd thing, I can tranfer files without a problem, its when we download them from ftp or http is when we are havign the issue. I wonder if its in my Datacenters filtering devices? hmmm...

Thanks for the replies! I will also work on some packet captures and see if I can detect anything wrong there.

Thanks again!


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