my %hoh  = ( '111' => { switch  => 'on',
                        ip      => '10.1.1.1',
                        version => '12.1(SAG1)'},
             '222' => { switch  => 'off',
                        ip      => '12.1.1.1',
                        version => '12.4(FCL5)'},
             '333' => { switch  => 'null',
                        ip      => '13.1.1.1',
                        version => '12.1(5)'},
             );
# $hoh{333}{switch} = 'null';

##</code><code>##

            '333' => { switch  => 'null',
                       ip      => ['13.1.1.1','13.2.2.2','13.3.3.3'],
                       version => '12.1(5)'},