Try this out.

use strict;
use warnings;

# See perlvar for why $/ = "" causes $record to contain your entire re
+cord at once. The point is to read your data record-at-a-time instead
+ of line-at-a-time.
local $/ = "";
while ( my $record = <DATA> ) {

    # See perlre for why (.+) fetches everything on the same line as t
+he text being matched but doesn't continue onto the next line. Rememb
+er, $record is a multi-line string.
    my ( $pc_name ) = $record =~ /interface (.+)/;
    my ( $switch_name ) = $record =~ /switchport description (.+)/;

    print "$pc_name: $switch_name\n";
}
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