<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM XIRCOM,
INC.'S FORM 10-K FOR THE YEAR ENDED SEPTEMBER 30, 2000 AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> 12-MOS
<FISCAL-YEAR-END> SEP-30-2000
<PERIOD-START> OCT-01-1999
<PERIOD-END> SEP-30-2000
<CASH> 113,284
<SECURITIES> 195,205
<RECEIVABLES> 62,780
<ALLOWANCES> 9,577
<INVENTORY> 24,483
<CURRENT-ASSETS> 412,271
<PP&E> 121,290
<DEPRECIATION> 46,556
<TOTAL-ASSETS> 541,549
<CURRENT-LIABILITIES> 73,456
<BONDS> 0
0
0
<COMMON> 30
<OTHER-SE> 450,929
<TOTAL-LIABILITY-AND-EQUITY> 541,549
<SALES> 496,199
<TOTAL-REVENUES> 496,199
<CGS> 279,318
<TOTAL-COSTS> 279,318
<OTHER-EXPENSES> 185,122
<LOSS-PROVISION> 0
<INTEREST-EXPENSE> 97
<INCOME-PRETAX> 41,091
<INCOME-TAX> 16,063
<INCOME-CONTINUING> 25,028
<DISCONTINUED> 0
<EXTRAORDINARY> 0
<CHANGES> 0
<NET-INCOME> 25,028
<EPS-BASIC> .87
<EPS-DILUTED> .82
</TABLE>