Before asking anyone to take a look at this please consider

• adding use strict; use warnings;
• define those variables
• is SNMP_util something you've rolled your own or is this a cpan module?
• Use open the three argument open (as per the docs), and report $! on failure (... or die "can't open file: $!";)
• Consistent indentation wouldn't go a miss (Perl::Tidy)
• Not a Cisco guy, but is there something on cpan to make this easier for you, e.g. Cisco::UCS?