Exhibit 31.2

CERTIFICATION

I, Timothy D.
Heffner, certify that:

|1. | I
have reviewed this Quarterly Report on Form 10-Q of Foundry Networks, Inc.;
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|2. | Based
on my knowledge, this 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 report;
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|3. | Based
on my knowledge, the financial statements, and other financial information  included in
this 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 report;
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|4. | The
registrants other certifying officers and I are responsible for  establishing and
maintaining disclosure controls and procedures (as defined in  Exchange Act Rules
13a-15(e) and 15d-15(e)) for the registrant and have:
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| | (a) | designed
such disclosure controls and procedures, or caused such disclosure  controls and
procedures to be designed under our supervision, to ensure that  material information
relating to the registrant, including its consolidated  subsidiaries, is made known to us
by others within those entities, particularly  during the period in which this report is
being prepared;
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| | (b) | [Paragraph
omitted pursuant to SEC Release 33-8238];
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| | (c) | 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
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| | (d) | disclosed
in this report any change in the registrants internal control  over financial
reporting that occurred during the registrants most recent  fiscal quarter that has
materially affected, or is reasonably likely to  materially affect, the registrants
internal control over financial  reporting; and
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|5. | The
registrants other certifying officers and I have disclosed, based on  our most
recent evaluation of internal control over financial reporting, to the  registrants
auditors and the audit committee of the registrants  board of directors (or persons
performing the equivalent function):
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| | (a) | all
significant deficiencies and material weaknesses in the design or operation  of internal
control over financial reporting which are reasonably likely to  adversely affect the
registrants ability to record, process, summarize and  report financial
information; and
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| | (b) | any
fraud, whether or not material, that involves management or other employees  who have a
significant role in the registrants internal control over  financial reporting.
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| |                        
| | -----------------------
| | /s/ Timothy D. Heffner 
| | Timothy D. Heffner     
| | Chief Financial Officer
| | November 14, 2003