SECURITIES AND EXCHANGE COMMISSION
                           WASHINGTON, D.C. 20549

                                SCHEDULE TO
                               (RULE 14d-100)
         TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1)
                   OF THE SECURITIES EXCHANGE ACT OF 1934
                             (Amendment No. 2)


                          Sycamore Networks, Inc.
                     (Name of Subject Company (Issuer))


                          Sycamore Networks, Inc.
                     (Name of Filing Person (Offeror))


       Options under the Sycamore Networks, Inc. 1999 Stock Incentive
          Plan, as Amended, the Sycamore Networks, Inc. 1998 Stock
                        Incentive Plan, as Amended,
            and the Sirocco Systems, Inc. 1998 Stock Option Plan
            to Purchase Common Stock, Par Value $.001 Per Share,
            Having an Exercise Price Per Share of $7.25 or More
                       (Title of Class of Securities)


                                871206 10 8
                   (CUSIP Number of Class of Securities)
                         (Underlying Common Stock)


                             Frances M. Jewels
                          Sycamore Networks, Inc.
                              150 Apollo Drive
                            Chelmsford, MA 01824
                               (978) 250-2900
        (Name, Address and Telephone Number of Person Authorized to
       Receive Notices and Communications on Behalf of Filing Person)

                                  Copy to:

                             Margaret A. Brown
                  Skadden, Arps, Slate, Meagher & Flom LLP
                             One Beacon Street
                              Boston, MA 02108
                         Telephone: (617) 573-4800
                         Facsimile: (617) 573-4822



                         CALCULATION OF FILING FEE

===============================================================================

    Transaction Valuation*                           Amount of Filing Fee
- -------------------------------------------------------------------------------
        $102,293,765                                       $20,459
===============================================================================

*        Calculated solely for purposes of determining the filing fee. This
         amount assumes that options to purchase 24,961,963 shares of
         common stock of Sycamore Networks, Inc. having an aggregate value
         of $102,293,765 as of May 16, 2001 will be exchanged pursuant to
         this offer. The aggregate value of such options was calculated
         based on the Black-Scholes option pricing model. The amount of the
         filing fee, calculated in accordance with Rule 0-11 of the
         Securities Exchange Act of 1934, as amended, equals 1/50th of one
         percent of the aggregate value of this transaction.


|X|      Check the box if any part of the fee is offset as provided by Rule
         0-11(a)(2) and identify the filing with which the offsetting fee
         was previously paid. Identify the previous filing by registration
         statement number, or the Form or Schedule and the date of its
         filing.

Amount Previously Paid:  $20,459       Filing Party:  Sycamore Networks, Inc.
Form or Registration No.:  5-58421     Date Filed:  May 18, 2001

|_|      Check the box if the filing relates solely to preliminary
         communications made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which
the statement relates:

         |_|      third-party tender offer subject to Rule 14d-1.
         |X|      issuer tender offer subject to Rule 13e-4.
         |_|      going-private transaction subject to Rule 13e-3.
         |_|      amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the
results of the tender offer: |_|



                           INTRODUCTORY STATEMENT

         This Amendment No. 2 amends and supplements the Tender Offer
Statement on Schedule TO filed with the Securities and Exchange Commission
(the "Commission") on May 18, 2001, as amended by Amendment No. 1 filed
with the Commission on June 1, 2001 (together, the "Schedule TO"), relating
to the offer (the "Offer") by Sycamore Networks, Inc. (the "Company") to
exchange all options outstanding under the Company's 1999 Stock Incentive
Plan, as amended (the "1999 Incentive Plan"), the Company's 1998 Stock
Incentive Plan, as amended, and the Sirocco Systems, Inc. 1998 Stock Option
Plan to purchase shares of the Company's common stock, par value $.001 per
share (the "Common Stock"), having an exercise price of $7.25 or more for
(1) unvested shares of restricted Common Stock granted under the 1999
Incentive Plan and (2) new options to purchase shares of Common Stock to be
granted under the 1999 Incentive Plan, upon the terms and subject to the
conditions described in the Offer to Exchange and the related Letter of
Transmittal.

         The Company filed an amended and restated Letter of Transmittal as
exhibit (a)(2) to Amendment No. 1 to the Tender Offer Statement on Schedule
TO filed with the Commission on June 1, 2001. The amended and restated
Letter of Transmittal deleted the acknowledgement in previously numbered
paragraph 20 on page 7 that employees have "read" and "understand" all of
the terms and conditions of the Offer. The Company will not rely upon or
enforce this acknowledgement in any Letter of Transmittal distributed to
employees prior to the amendment and restatement of the Letter of
Transmittal and will not include this acknowledgment in any Letter of
Transmittal subsequently distributed to employees in connection with the
Offer.

Item 12.  Exhibits.

(a)(1)    Offer to Exchange dated May 18, 2001.*

(a)(2)    Letter of Transmittal.*

(a)(3)    Letter to Eligible Option Holders.*

(a)(4)    Form of Letter to Tendering Option Holders.*

(a)(5)    E-mail communication to Sycamore Networks, Inc. Employees
          dated May 18, 2001.*

(a)(6)    Form of Personnel Option Status schedule.*

(a)(7)    Form of E-mail confirmation to Tendering Option Holders.*

(a)(8)    Form of Irrevocable Standing Order to Sell Shares.*

(a)(9)    Sycamore Networks, Inc. Current Report on Form 8-K filed with
          the Securities and Exchange Commission on May 18, 2001 and
          incorporated herein by reference.

(a)(10)   Sycamore Networks, Inc. Quarterly Report on Form 10-Q for
          its fiscal quarter ended January 27, 2001, filed with the
          Securities and Exchange Commission on March 13, 2001 and
          incorporated herein by reference.

(b)       Not applicable.

(d)(1)    Sycamore Networks, Inc. 1998 Stock Incentive Plan,
          as amended.*

(d)(2)    Sycamore Networks, Inc. 1999 Stock Incentive Plan, as
          amended.*

(d)(3)    Sirocco Systems, Inc. 1998 Stock Option Plan.*

(d)(4)    Form of New Option Agreement pursuant to the Company's 1999
          Stock Incentive Plan.*

(d)(5)    Form of Restricted Stock Agreement pursuant to the Company's
          1999 Stock Incentive Plan.*

(d)(6)    Second Amended and Restated Investor Rights Agreement dated
          February 26, 1999, as amended by Amendment No. 1 dated as of
          July 23, 1999.*

(d)(7)    Amendment No. 2 dated as of August 5, 1999 to the Second
          Amended and Restated Investor Rights Agreement dated
          February 26, 1999.*

(d)(8)    Amendment No. 3 dated as of September 20, 1999 to the Second
          Amended and Restated Investor Rights Agreement dated
          February 26, 1999.*

(d)(9)    Amendment No. 4 dated as of February 11, 2000 to the Second
          Amended and Restated Investor Rights Agreement dated
          February 26, 1999.*

(g)       Not applicable.

(h)       Not applicable.


*  Previously filed.



                                 SIGNATURE

         After due inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this Schedule TO is true,
complete and correct.


                       SYCAMORE NETWORKS, INC.

                       By: /s/ Frances M. Jewels
                          ------------------------
                       Name:   Frances M. Jewels
                       Title:  Chief Financial Officer,
                               Vice President, Finance and Administration,
                               Treasurer and Secretary


Date:  June 4, 2001



                             INDEX TO EXHIBITS

EXHIBIT
NUMBER            DESCRIPTION OF EXHIBIT

(a)(1)            Offer to Exchange dated May 18, 2001.*

(a)(2)            Letter of Transmittal.*

(a)(3)            Letter to Eligible Option Holders.*

(a)(4)            Form of Letter to Tendering Option Holders *

(a)(5)            E-mail communication to Sycamore Networks, Inc.
                  Employees dated May 18, 2001.*

(a)(6)            Form of Personnel Option Status schedule.*

(a)(7)            Form of E-mail confirmation to Tendering Option Holders.*

(a)(8)            Form of Irrevocable Standing Order to Sell Shares.*

(a)(9)            Sycamore Networks, Inc. Current Report on Form 8-K filed with
                  the Securities and Exchange Commission on May 18, 2001 and
                  incorporated herein by reference.

(a)(10)           Sycamore Networks, Inc. Quarterly Report on Form
                  10-Q for its fiscal quarter ended January 27,
                  2001, filed with the Securities and Exchange
                  Commission on March 13, 2001 and incorporated
                  herein by reference.

(b)               Not applicable.

(d)(1)            Sycamore Networks, Inc. 1998 Stock Incentive Plan, as
                  amended.*

(d)(2)            Sycamore Networks, Inc. 1999 Stock Incentive Plan, as
                  amended.*

(d)(3)            Sirocco Systems, Inc. 1998 Stock Option Plan.*

(d)(4)            Form of New Option Agreement pursuant to the Company's 1999
                  Stock Incentive Plan.*

(d)(5)            Form of Restricted Stock Agreement pursuant to the Company's
                  1999 Stock Incentive Plan.*

(d)(6)            Second Amended and Restated Investor Rights Agreement dated
                  February 26, 1999, as amended by Amendment No. 1 dated as of
                  July 23, 1999.*

(d)(7)            Amendment No. 2 dated as of August 5, 1999 to the Second
                  Amended and Restated Investor Rights Agreement dated
                  February 26, 1999.*

(d)(8)            Amendment No. 3 dated as of September 20, 1999 to the Second
                  Amended andRestated Investor Rights Agreement dated
                  February 26, 1999.*

(d)(9)            Amendment No. 4 dated as of February 11, 2000 to the Second
                  Amended and Restated Investor Rights Agreement dated
                  February 26, 1999.*

(g)               Not applicable.

(h)               Not applicable.

*  Previously filed.