my $var = new SNMP::Varbind( [ $target ] );
my $value = $session->get($var)
      || warn "SNMP ERROR: $session->{ErrorStr}";
print "name: ", $var->name, "\n";
print "type: ", $var->type, "\n";
if ( $var->type eq "IPADDR" ) {
   ... unpack $var->val here ...
}
elsif ( $var->type eq "COUNTER" ) {
   ... unpack $var->val here ...
}
elsif ...