[ This is a different spin on the same answer. ]

split's first argument isn't matched literally. It's treated as a regex pattern. The regex pattern can be provided as any of the following:

• a string,
• a compiled pattern
• a match operator (which passes a compiled pattern)

The following are equivalent:

my @octets = split('\\.',  $ip);
my @octets = split(qr/\./, $ip);
my @octets = split(/\./,   $ip);
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I always use the last syntax. It avoids confusion.

You might also be interested in Socket's inet_aton (and inet_ntoa).

(Note that split ' ' is special. See split's documentation if you're interested in details.)