SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                   FORM 8-K

                                CURRENT REPORT
                    Pursuant to Section 13 or 15(d) of the
                        Securities Exchange Act of 1934


                               October 18, 2001
               Date of Report (Date of earliest event reported)

                            SYCAMORE NETWORKS, INC.
            (Exact name of registrant as specified in its charter)


                       Commission file number: 000-27273


           DELAWARE                                      04-3410558
(State or other jurisdiction of                       (I.R.S. Employer
incorporation or organization)                       Identification No.)



                               150 APOLLO DRIVE
                        CHELMSFORD, MASSACHUSETTS 01824
                    (Address of principal executive office)
      Registrant's telephone number, including area code: (978) 250-2900


                                NOT APPLICABLE
         (Former name or former address, if changed since last report)





ITEM 5: OTHER EVENTS

On October 18, 2001, the Registrant issued a press release providing revised
guidance as to its revenue and earnings for its fiscal first quarter ending
October 27, 2001. A copy of the Registrant's press release dated October 18,
2001 is attached as Exhibit 99.1 hereto and incorporated by reference herein.

ITEM 7: FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS

(c) Exhibits.

        99.1   Press Release dated October 18, 2001








                                 SIGNATURE


Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.


Sycamore Networks, Inc.


/s/ Frances M. Jewels
-----------------------------------
Frances M. Jewels
Chief Financial Officer
(Duly Authorized Officer and Principal
Financial and Accounting Officer)


Dated: October 19, 2001





                                EXHIBIT INDEX

Exhibit
Number                          Description

99.1                            Press Release dated October 18, 2001.




                                                                   EX-99.1


SYCAMORE NETWORKS, INC. UPDATES FINANCIAL OUTLOOK

CHELMSFORD, Mass., October 18, 2001 - Sycamore Networks, Inc. (NASDAQ: SCMR)
announced today that its financial results for the fiscal first quarter ending
October 27, 2001, will be lower than previously anticipated due to the
continued deceleration of spending in the telecommunications sector. Sycamore
currently anticipates that fiscal first quarter revenue will be in the range
of $20 to $25 million.

Based on current business conditions, the Company is implementing a
restructuring of its operations. In the first quarter, Sycamore expects to
record restructuring and other charges in the range of $200 to $210 million.
These charges comprise the following:

o        A $100 to $105 million charge associated with excess inventory and
         purchase commitments;

o        A $7 to $8 million charge related to workforce reductions of
         approximately 240 employees; and

o        A $93 to $97 million charge for consolidation of facilities and the
         write-down of certain impaired assets as well as certain strategic
         equity investments.

The Company expects to report a pro forma net loss for the fiscal first
quarter, which excludes amortization of deferred stock compensation, payroll
taxes on stock option exercises, restructuring and other charges, in the range
of $40 million, or $(0.16) per share, to $44 million, or $(0.18) per share.

"The downturn in capital spending in the telecommunications sector continues
to impact Sycamore's business," stated Dan Smith, Sycamore's president and
chief executive officer. "Without clear signs of a turnaround in customer
spending, Sycamore is taking action to reduce expenses and resize the business
for this new economic environment. We made a difficult but necessary decision
to reduce our workforce and we are in the process of transitioning the
individuals impacted by our business decision. We remain focused on providing
resources to critical technology initiatives and sales and support services so
that we may capitalize on opportunities as market conditions improve."


Conference Call and Webcast

Sycamore plans to review the items contained in this press release during a
conference call today beginning at 5:00 p.m. EDT. To participate
telephonically, please dial (877) 330-4539 (domestically) or (416) 641-6449
(internationally) at least 15 minutes prior to the start of the call. The call
also will be broadcast live over the Internet. To listen to the Webcast, visit
the investor relations section of Sycamore's Web site, located at
www.sycamorenet.com. Interested investors are encouraged to log onto the
Webcast at least 15 minutes prior to call. Participating in the call will be
Sycamore's president and chief executive officer Daniel E. Smith and chief
financial officer Frances M. Jewels. A rebroadcast of the call will be
available through audio archiving on Sycamore's Web site. In addition, a
telephone replay will be available for 48 hours, beginning at 8:00 p.m. EDT on
October 18, 2001, and continuing until 8:00 p.m. EDT on October 20, 2001. To
listen to the telephonic replay, dial (800) 633-8284 (domestically) or (858)
812-6440 (internationally), and designate reservation number 19894377.

About Sycamore Networks

Sycamore Networks (NASDAQ: SCMR) develops and markets intelligent optical
networking products that transport voice and data traffic over wavelengths of
light. The Company combines significant experience in data networking with
expertise in optics to develop intelligent optical networking solutions for
network service providers. Sycamore's products are based on a common software
foundation, enabling concentration on the delivery of services and end-to-end
optical networking. Sycamore's products and product plans include optical
transport, access and switching systems and end-to-end optical network
management solutions. Contact Sycamore Networks at www.sycamorenet.com.

Except for the historical information contained herein, we wish to caution you
that certain matters discussed in this news release constitute forward-looking
statements that involve risks and uncertainties. The Company's actual results
could differ materially from those stated or implied in forward-looking
statements due to a number of factors, including but not limited to the rate
of product purchases by current and prospective customers; general economic
conditions including, stock market volatility and capital market conditions;
uncertainty resulting from recent terrorist acts; conditions specific to the
telecommunications, Internet and related industries; the commercial success of
the Company's line of intelligent optical networking products; the Company's
reliance on a limited number of customers; new product introductions and
enhancements by the Company and its competitors; the length and variability of
the sales cycles for the Company's products; competition; manufacturing and
sourcing risks; variations in the Company's quarterly results and the other
factors discussed in the Company's most recently filed Annual Report on Form
10-K and the other reports filed by the Company from time to time with the
Securities and Exchange Commission. The Company disclaims any intention or
obligation to update or revise any forward-looking statements, whether as a
result of new information, future results or otherwise.
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SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                   FORM 8-K

                                CURRENT REPORT
                    Pursuant to Section 13 or 15(d) of the
                        Securities Exchange Act of 1934

                               October 18, 2001
               Date of Report (Date of earliest event reported)

                            SYCAMORE NETWORKS, INC.
            (Exact name of registrant as specified in its charter)

                       Commission file number: 000-27273

           DELAWARE                                      04-3410558
(State or other jurisdiction of                       (I.R.S. Employer
incorporation or organization)                       Identification No.)

                               150 APOLLO DRIVE
                        CHELMSFORD, MASSACHUSETTS 01824
                    (Address of principal executive office)
      Registrant's telephone number, including area code: (978) 250-2900

                                NOT APPLICABLE
         (Former name or former address, if changed since last report)

ITEM 5: OTHER EVENTS

On October 18, 2001, the Registrant issued a press release providing revised
guidance as to its revenue and earnings for its fiscal first quarter ending
October 27, 2001. A copy of the Registrant's press release dated October 18,
2001 is attached as Exhibit 99.1 hereto and incorporated by reference herein.

ITEM 7: FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS

(c) Exhibits.

        99.1   Press Release dated October 18, 2001

                                 SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

Sycamore Networks, Inc.

/s/ Frances M. Jewels
-----------------------------------
Frances M. Jewels
Chief Financial Officer
(Duly Authorized Officer and Principal
Financial and Accounting Officer)

Dated: October 19, 2001

                                EXHIBIT INDEX

Exhibit
Number                          Description

99.1                            Press Release dated October 18, 2001.

                                                                   EX-99.1

SYCAMORE NETWORKS, INC. UPDATES FINANCIAL OUTLOOK

CHELMSFORD, Mass., October 18, 2001 - Sycamore Networks, Inc. (NASDAQ: SCMR)
announced today that its financial results for the fiscal first quarter ending
October 27, 2001, will be lower than previously anticipated due to the
continued deceleration of spending in the telecommunications sector. Sycamore
currently anticipates that fiscal first quarter revenue will be in the range
of $20 to $25 million.

Based on current business conditions, the Company is implementing a
restructuring of its operations. In the first quarter, Sycamore expects to
record restructuring and other charges in the range of $200 to $210 million.
These charges comprise the following:

o        A $100 to $105 million charge associated with excess inventory and
         purchase commitments;

o        A $7 to $8 million charge related to workforce reductions of
         approximately 240 employees; and

o        A $93 to $97 million charge for consolidation of facilities and the
         write-down of certain impaired assets as well as certain strategic
         equity investments.

The Company expects to report a pro forma net loss for the fiscal first
quarter, which excludes amortization of deferred stock compensation, payroll
taxes on stock option exercises, restructuring and other charges, in the range
of $40 million, or $(0.16) per share, to $44 million, or $(0.18) per share.

"The downturn in capital spending in the telecommunications sector continues
to impact Sycamore's business," stated Dan Smith, Sycamore's president and
chief executive officer. "Without clear signs of a turnaround in customer
spending, Sycamore is taking action to reduce expenses and resize the business
for this new economic environment. We made a difficult but necessary decision
to reduce our workforce and we are in the process of transitioning the
individuals impacted by our business decision. We remain focused on providing
resources to critical technology initiatives and sales and support services so
that we may capitalize on opportunities as market conditions improve."

Conference Call and Webcast

Sycamore plans to review the items contained in this press release during a
conference call today beginning at 5:00 p.m. EDT. To participate
telephonically, please dial (877) 330-4539 (domestically) or (416) 641-6449
(internationally) at least 15 minutes prior to the start of the call. The call
also will be broadcast live over the Internet. To listen to the Webcast, visit
the investor relations section of Sycamore's Web site, located at
www.sycamorenet.com. Interested investors are encouraged to log onto the
Webcast at least 15 minutes prior to call. Participating in the call will be
Sycamore's president and chief executive officer Daniel E. Smith and chief
financial officer Frances M. Jewels. A rebroadcast of the call will be
available through audio archiving on Sycamore's Web site. In addition, a
telephone replay will be available for 48 hours, beginning at 8:00 p.m. EDT on
October 18, 2001, and continuing until 8:00 p.m. EDT on October 20, 2001. To
listen to the telephonic replay, dial (800) 633-8284 (domestically) or (858)
812-6440 (internationally), and designate reservation number 19894377.

About Sycamore Networks

Sycamore Networks (NASDAQ: SCMR) develops and markets intelligent optical
networking products that transport voice and data traffic over wavelengths of
light. The Company combines significant experience in data networking with
expertise in optics to develop intelligent optical networking solutions for
network service providers. Sycamore's products are based on a common software
foundation, enabling concentration on the delivery of services and end-to-end
optical networking. Sycamore's products and product plans include optical
transport, access and switching systems and end-to-end optical network
management solutions. Contact Sycamore Networks at www.sycamorenet.com.

Except for the historical information contained herein, we wish to caution you
that certain matters discussed in this news release constitute forward-looking
statements that involve risks and uncertainties. The Company's actual results
could differ materially from those stated or implied in forward-looking
statements due to a number of factors, including but not limited to the rate
of product purchases by current and prospective customers; general economic
conditions including, stock market volatility and capital market conditions;
uncertainty resulting from recent terrorist acts; conditions specific to the
telecommunications, Internet and related industries; the commercial success of
the Company's line of intelligent optical networking products; the Company's
reliance on a limited number of customers; new product introductions and
enhancements by the Company and its competitors; the length and variability of
the sales cycles for the Company's products; competition; manufacturing and
sourcing risks; variations in the Company's quarterly results and the other
factors discussed in the Company's most recently filed Annual Report on Form
10-K and the other reports filed by the Company from time to time with the
Securities and Exchange Commission. The Company disclaims any intention or
obligation to update or revise any forward-looking statements, whether as a
result of new information, future results or otherwise.