while (<DATA>) {
	chomp;
	print "\n$1 =" and next if /^(interface\s.+)/;
	print "$1" and next if /^\s+(switchport description\s.+)/;
}

##</code><code>##

my (%data, $last);
while (<DATA>) {
	#~ print STDERR $_;
	chomp;
	if (/^(interface\s.+)/) {
		$last = $1; 
		$data{$last} = '';
		next;
	}
	$data{$last}=$1 and next if /^\s+(switchport description\s.+)/;
}

##now print
for ( sort keys %data ) { print "$_ = $data{$_}\n" }