Just swap the if block with the elsif block and everything works fine.
However, the regular expressions are not very good written.

You might want something like this:

#!perl

my @lens;
while (<DATA>) {
    /\S/ || next;

    my $pos   = tell(DATA);
    my $nline = <DATA>;
    if ($nline =~ /-/ && $nline =~ /^[-\s]+$/) {
        @lens = map { length() + 1 } split(' ', $nline);
        next;
    }
    else {
        seek DATA, $pos, 0;
    }

    my @values = map { s{^\s+}{}; $_ } unpack(join('', map { "A${_}" }
+ @lens), $_);
    if (@lens == 5) {
        print "================= IF 1 =================\n";
        print "SLOT: $values[0]\n";
        print "PORTAS: $values[1]\n";
        print "DESC: $values[2]\n";
        print "Model: $values[3]\n";
        print "Sw: $values[4]\n";
        print "\n";
    }
    elsif (@lens == 6) {
        print "================= ELSIF =================\n";
        print "<> Slot: $values[0]\n";
        print "<> Desc: $values[1]\n";
        print "<> Model: $values[2]\n";
        print "<> Sw: $values[3]\n";
        print "<> Hw: $values[4]\n";
        print "<> Status: $values[5]\n";
        print "\n";
    }

}
close(DATA);

__DATA__
Mod Ports Card Type                              Model              Se
+rial No.
--- ----- -------------------------------------- ------------------ --
+---------
  1   24  CEF720 24 port 1000mb SFP              WS-X6724-SFP       SA
+L1434RA09
  3   20  7600 ES+T                              76-ES+T-20G        JA
+E14530455
  5    2  Route Switch Processor 720 (Active)    RSP720-3CXL-GE     JA
+E14330N9B
  6    2  Route Switch Processor 720 (Hot)       RSP720-3CXL-GE     JA
+E14330NA6
  7    4  CEF720 4 port 10-Gigabit Ethernet      WS-X6704-10GE      SA
+L1433QVJQ
  8    4  CEF720 4 port 10-Gigabit Ethernet      WS-X6704-10GE      SA
+L1433QVJW

Mod  Sub-Module                  Model              Serial       Hw   
+  Status
---- --------------------------- ------------------ ----------- ------
+- -------
  1  Distributed Forwarding Card WS-F6700-DFC3CXL   SAL1434RLPY  1.6  
+  Ok
  3  7600 ES+ DFC XL             7600-ES+3CXL       JAE14520N29  1.2  
+  Ok
  3  7600 ES+T 20x1GE SFP        76-ES+T-20GQ       JAE145301XM  1.1  
+  Ok
  5  Policy Feature Card 3       7600-PFC3CXL       JAE14330E6J  1.1  
+  Ok
  5  C7600 MSFC4 Daughterboard   7600-MSFC4         JAE14320QBE  1.6  
+  Ok
  6  Policy Feature Card 3       7600-PFC3CXL       JAE14330EAO  1.1  
+  Ok
  6  C7600 MSFC4 Daughterboard   7600-MSFC4         JAE14320QA8  1.6  
+  Ok
  7  Distributed Forwarding Card WS-F6700-DFC3CXL   SAL1433QHBR  1.6  
+  Ok
  8  Distributed Forwarding Card WS-F6700-DFC3CXL   SAL1433QXF9  1.6  
+  Ok
[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.