In my case I have found that some devices return strange output, it is in case no mgmt IP is available in sh cdp nei detail (CSS11501), older IOS or different platform. 
DB<69> p $_[0]
DB<70> x $_[0]
0  "\c@\c@\c@\c@"

[download]
My dirty hack for that was just check for valid hex-like input 
          #if (substr($hex_ip,0,1) eq ""){
          if ($hex_ip !~ m/0x.*/){
          $ip = "0.0.0.0";
            }

[download]

In reply to Re^3: Cisco SNMP CDP Poll by Anonymous Monk
in thread Cisco SNMP CDP Poll by fingers

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