<PAGE>
 
                                                                    EXHIBIT 11.1

                         NEWBRIDGE NETWORKS CORPORATION

                        COMPUTATION OF EARNINGS PER SHARE

             (Accounting principles generally accepted in Canada) 
        (Canadian dollars, amounts in thousands except per share data)
                                  (Unaudited)
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                                                              Fiscal quarter ended
                                                            ------------------------
                                                             Aug 3,          Jul 28,
                                                              1997            1996
                                                            --------        --------  
<S>                                                         <C>             <C> 
BASIC EARNINGS PER SHARE                                               
                                                                       
    Net earnings                                            $ 64,354        $ 60,801
                                                            ========        ========
    Common Shares outstanding                                          
       at the beginning of the period                        171,859         168,676
                                                                       
    Weighted average number of Common Shares                           
       issued during the period                                1,105             552
                                                            --------        --------  
    Weighted average number of Common Shares                           
       outstanding during the period                         172,964         169,228
                                                            ========        ========
                                                                        
    Basic earnings per share                                $   0.37        $   0.36    
                                                            ========        ========
                                                                       
FULLY DILUTED EARNINGS PER SHARE                                       
                                                                       
    Earnings before imputed earnings                        $ 64,354        $ 60,801
                                                                       
    After tax imputed earnings from the investment                     
       of funds received through dilution                      3,979           2,883
                                                            --------        --------  
                                                                       
    Adjusted net earnings                                   $ 68,333        $ 63,684
                                                            ========        ========
    Weighted average number of Common Shares                           
       outstanding during the period                         172,964         169,228
                                                                       
    Weighted average common share                                      
       equivalents based on conversion of                              
       outstanding stock options                              16,118          12,482
                                                            --------        --------  
    Weighted average number of Common                                  
       Shares and equivalents outstanding                              
       during the period                                     189,082         181,710
                                                            ========        ========
                                                                       
    Fully diluted earnings per share                        $  0 .36        $   0.35    
                                                            ========        ========
EARNINGS PER SHARE EXPRESSED IN U.S. DOLLARS                           
                                                                       
    Daily average exchange rate of a Canadian                          
       dollar for U.S. dollars as reported by the                      
       Federal Reserve Bank of New York                     $ 0.7242        $ 0.7309
                                                                       
    Basic earnings per share, in U.S. dollars               $   0.27        $   0.26    
                                                            ========        ========
                                                                       
    Fully diluted earnings per share, in U.S. dollars       $   0.26        $   0.26    
                                                            ========        ========
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