Exhibit 31.2



I, Thomas L. Cronan III, certify that:



1. I have reviewed this annual report on Form 10-K of Redback Networks Inc.;



2. Based on my knowledge, this annual report does not contain
any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this annual
report;



3. Based on my knowledge, the financial statements,
and other financial information included in this annual report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this annual report;



4. The registrants other certifying officer and I are
responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-14 and 15d-14) for the registrant and we have:



| | a) | evaluated the effectiveness of the registrants disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure
controls and procedures, as of the end of the period covered by this report based on such evaluation; and
| | -- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | b) | disclosed in this report any change in the registrants internal control over financial reporting that occurred during the registrants fourth fiscal quarter that has
materially affected, or is reasonably likely to materially affect, the registrants internal control over financial reporting;
| | -- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | c) | presented in this annual report our conclusions about the effectiveness of the disclosure controls and procedures based on our evaluation as of the Evaluation Date;
| | -- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------



5. The registrants other certifying
officer and I have disclosed, based on our most recent evaluation, to the registrants auditors and the audit committee of registrants board of directors (or persons performing the equivalent functions):



| | a) | all significant deficiencies in the design or operation of internal controls which could adversely affect the registrants ability to record, process, summarize and report
financial data and have identified for the registrants auditors any material weaknesses in internal controls; and
| | -- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | b) | any fraud, whether or not material, that involves management or other employees who have a significant role in the registrants internal controls; and
| | -- | ------------------------------------------------------------------------------------------------------------------------------------------------------



|                     |  |  |  |                                                                                                  
|-------------------- |  |  |  | -------------------------------------------------------------------------------------------------
|                     |  | 
|Date: March 15, 2004 |  |  |  | /s/ THOMAS L. CRONAN III                                                                         
|                     |  |  |  |                                                                                                  
|                     |  |  |  | Thomas L. Cronan III Chief Financial Officer, Senior Vice President of Finance and Administration