my @data = qw( workstation_1_1 workstation_1_2 
               voiceserver_1_2 voiceserver_1_1 );
my @sorted = map {
               join('_', @{$_} ) # put the data back together again
             }
             sort {
                  $a->[2] <=> $b->[2] # first sort by the final digit
               || $b->[0] cmp $a->[0] # then by the name, descending
             }
             map { 
               # seperate the data out into seperate "fields" for easy
               # sorting (typically called a "Schwartzian Transform")
               [ split(/_/,$_) ] 
             } 
             @data; # the operation starts here (believe it or not)