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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 MtWkOP/2b0vklpjvuM0pK0vtp11seVqjuhPABn+jgF1nJIm9qMetsgSuIWjQanOG
 6c/gN2CdN+5naGOK38M9PA==

<SEC-DOCUMENT>0001209191-03-035930.txt : 20031219
<SEC-HEADER>0001209191-03-035930.hdr.sgml : 20031219
<ACCEPTANCE-DATETIME>20031219123214
ACCESSION NUMBER:		0001209191-03-035930
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031219
FILED AS OF DATE:		20031219

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			FERRI PAUL J
		CENTRAL INDEX KEY:			0001012501

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-27273
		FILM NUMBER:		031064251

	MAIL ADDRESS:	
		STREET 1:		C/O MATRIX PARTNERS
		STREET 2:		1000 WINTER STREET, SUITE 4500
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SYCAMORE NETWORKS INC
		CENTRAL INDEX KEY:			0001092367
		STANDARD INDUSTRIAL CLASSIFICATION:	TELEPHONE & TELEGRAPH APPARATUS [3661]
		IRS NUMBER:				043410558
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0731

	BUSINESS ADDRESS:	
		STREET 1:		220 MILL ROAD
		CITY:			CHELMSFORD
		STATE:			MA
		ZIP:			01824
		BUSINESS PHONE:		9782502900

	MAIL ADDRESS:	
		STREET 1:		220 MILL ROAD
		CITY:			CHELMSFORD
		STATE:			MA
		ZIP:			01824
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>b48869pf.xml
<DESCRIPTION>MAIN DOCUMENT DESCRIPTION
<TEXT>
<XML>
<?xml version="1.0"?><ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2003-12-19</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0001092367</issuerCik><issuerName>SYCAMORE NETWORKS INC</issuerName>        <issuerTradingSymbol>SCMR</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001012501</rptOwnerCik><rptOwnerName>FERRI PAUL J</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1>C/O MATRIX PARTNERS</rptOwnerStreet1><rptOwnerStreet2>1000 WINTER STREET, SUITE 4500</rptOwnerStreet2><rptOwnerCity>WALTHAM</rptOwnerCity><rptOwnerState>MA</rptOwnerState><rptOwnerZipCode>02451</rptOwnerZipCode><rptOwnerStateDescription></rptOwnerStateDescription></reportingOwnerAddress><reportingOwnerRelationship><isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDeri
vativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>100818</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Partnership</value><footnoteId id="F1" /></natureOfOwnership></ownershipNature></nonDerivativeHolding><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>294735</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeTransaction><securityTitle><value>Non-Qualified Stock Option (right to buy)</value></securityTitle><conversionOrExercisePrice><value>4.59</value></conversionOrExercisePrice><transactionDate><value>2003-1
2-18</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>30000</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2003-12-18</value></exerciseDate><expirationDate><value>2013-12-18</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>30000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>120000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership></ownershipNature></derivativeTransaction></derivat
iveTable><footnotes><footnote id="F1">By Matrix V Entrepreneurs Fund, L.P.  Affiliated partnership under common control.  The reporting person disclaims beneficial ownership of the securities indicated to the extent to which such person does not have an actual pecuniary interest in such securities.  The reporting herein of such securities shall not be construed as an admission that the undersigned is the beneficial owner of any such securities for purposes of Section 16 of the Securities Exchange Act of 1934 or for any other purpose.</footnote></footnotes><ownerSignature><signatureName>\s\ Paul J. Ferri</signatureName><signatureDate>2003-12-19</signatureDate></ownerSignature></ownershipDocument>

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