while(<DATA>){
     if(/port-channel\s+(\d+)/ .. /]\s+\*/){
        $1 and $section = $1;
        $section || next;
        if(/\s+Ports:/ .. /\n\n/){
            /(\S+)\s+(\[\S+\])/
              and $data->{$section}{$1} = $2
        }
     }
}

use Data::Dumper; die Dumper($data)

__END__

$VAR1 = {
          '1' => {
                   'fc2/5' => '[up]',
                   'fc1/5' => '[up]'
                 },
          '3' => {
                   'fc1/1' => '[up]'
                 }
        };