my $month = qr{(?<month>\w+)};
# ...etc
my $re_dn = qr{^$month (\d+) (\d{2}:\d{2}:\d{2}) .*: eth(\d): link down};
my $re_dn = qr{^$month (\d+) (\d{2}:\d{2}:\d{2}) .*: eth(\d): link up, (\d+)Mbps, ([^,]+), lpa (\w+)};