Cisco 6Ks, telnet denied after scan

[Datdamwuf Datdamwuf]

Scanning some Cisco Cat 6000 series and during the scan telnet access was 
denied for about 30 minutes, happened on 4 of the devices.

Supposedly the 6Ks have a limited number of telnet sessions they can handle 
simultaneously , about 10 at once.

Nessus was run pretty much in default config with unneeded plugin groups 
turned off. I've searched the telnet plugins and can't find any that 
*should* cause this behavior. We didn't do any brute forcing.  I also didn't 
see enough Cisco specific telnet plugins that would attempt a login to hit 
the 10 session limit no matter how fast they ran...

Anyone seen something like this?  Any pointers on where to look in the logs 
to see if Nessus could have caused this?  For all we know the engineers were 
making config changes, willing to believe the scan could have been 
responsible but of course: if you are doing an audit and anything goes wrong 
it is always the security auditor that broke it....

TIA,
~D

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