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MDA configured for Linux PCs, but getting err-disable due to security violation

Hi all,

Sorry if this is a well known issue I couldn't find anything.  I am having troubles testing Linux PCs hanging off 797x phones with MDS configured on c3750's running 12.2(55)SE3.

I am working with a variety of PC builds at a customer site and I found when I shut/no shut the switch interfaces to clear the sessions, connect clean built desktop Linux machines to the phones, the 3750 switch ports err-disable themselves and logs say its a security violations, with (correct) machine MAC xxxxxx seen on interfaces fa1/0/x.  So far I've found this happens with RHEL v5 or v6, CentOS v6, and Fedora19.

Switch ports are are configured for multi-domain access and Windows7_x64 boxes and printers connect to the same phone access ports and all is OK. At first I thought I had a problem with _all_ Linux boxes but then Ubunu v12 and v13 worked fine. Retesting the others just shut the switch ports again. 

Yesterday I cleared the mac table shut/no shut the switch ports, even rebooted the phones and connected Windows and it all worked as expected.  I did the same with a Fedora box and the switch err-disabled again which is just nutz!  When I patch any of these boxes directly to a switch and they are all fine, but run them through a phone and the problem returns.  It seems like an MDA issue to me but I can't prove either way yet.

I'm not a big user of Linux but I believe Ubuntu is different in that its Debian-based and I'm told the others are all Red Hat based OS's.  So maybe something there to consider.. maybe?

Has anyone seen this before or can suggest anything please?  I have to go back to this customer in a couple of days and trying to get my head around this in the meantime.  Next I want to try this on their 6500s and see what happens.

Thanks in advance,



Re: MDA configured for Linux PCs, but getting err-disable due to

Hi Paul.
Please attach switch configuration where you recently viewed the issue


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