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                                                                     EXHIBIT 3.2



                              AMENDED AND RESTATED

                          CERTIFICATE OF INCORPORATION

                                       OF

                             SYCAMORE NETWORKS, INC.

     Sycamore Networks, Inc., a corporation organized and existing under and by
virtue of the General Corporation Law of the State of Delaware, does hereby
certify as follows:

     1.   The Corporation filed its original Certificate of Incorporation with
the Secretary of State of the State of Delaware (the "Delaware Secretary") on
February 17, 1998.  A Certificate of Amendment of Certificate of Incorporation
was filed with the Delaware Secretary on October 29, 1999.  A Certificate of
Amendment of Certificate of Incorporation was filed with the Delaware Secretary
on December 3, 1999.  A Certificate of Amendment of Certificate of Incorporation
was filed with the Delaware Secretary on February 25, 1999.  A Certificate of
Amendment of Certificate of Incorporation was filed with the Delaware Secretary
on July 23, 1999.

     2.   At a duly called meeting of the Board of Directors of the Corporation
at which a quorum was present at all times, a resolution was duly adopted,
pursuant to Sections 242 and 245 of the General Corporation Law of the State of
Delaware, setting forth an Amended and Restated Certificate of Incorporation of
the Corporation and declaring said Amended and Restated Certificate of
Incorporation advisable.  The stockholders of the Corporation duly approved said
proposed Amended and Restated Certificate of Incorporation by written consent in
accordance with Sections 228, 242 and 245 of the General Corporation Law of the
State of Delaware, and written notice of such consent has been given to all
stockholders who have not consented in writing to said restatement.  The
resolution setting forth the Amended and Restated Certificate of Incorporation
is as follows:

RESOLVED:   That the Certificate of Incorporation of the Corporation, be and
--------
            hereby is amended and restated in its entirety so that the same
            shall read as follows:

     FIRST.  The name of the Corporation is:

            Sycamore Networks, Inc.

     SECOND.  The address of its registered office in the State of Delaware is
Corporation Trust Center, 1209 Orange Street, in the City of Wilmington, County
<PAGE>

of New Castle.  The name of its registered agent at such address is The
Corporation Trust Company.

     THIRD.  The nature of the business or purposes to be conducted or promoted
by the Corporation is as follows:

     To engage in any lawful act or activity for which corporations may be
organized under the General Corporation Law of Delaware.

     FOURTH:  The total number of shares of all classes of stock which the
Corporation shall have authority to issue is 255,000,000 shares, consisting of
(i) 250,000,000 shares of Common Stock, $.001 par value per share ("Common
Stock"), and (ii) 5,000,000 shares of Preferred Stock, $.01 par value per share
("Preferred Stock").

     The following is a statement of the designations and the powers, privileges
and rights, and the qualifications, limitations or restrictions thereof in
respect of each class of capital stock of the Corporation.

A.   COMMON STOCK.
     ------------

     1.   General.  The voting, dividend and liquidation rights of the holders
          -------
of the Common Stock are subject to and qualified by the rights of the holders of
the Preferred Stock of any series as may be designated by the Board of Directors
upon any issuance of the Preferred Stock of any series.

     2.   Voting.  The holders of the Common Stock are entitled to one vote for
          ------
each share held at all meetings of stockholders.  There shall be no cumulative
voting.

     The number of authorized shares of Common Stock may be increased or
decreased (but not below the number of shares thereof then outstanding) by the
affirmative vote of the holders of a majority of the stock of the Corporation
entitled to vote, irrespective of the provisions of Section 242(b)(2) of the
General Corporation Law of Delaware.

     3.   Dividends.  Dividends may be declared and paid on the Common Stock
          ---------
from funds lawfully available therefor as and when determined by the Board of
Directors and subject to any preferential dividend rights of any then
outstanding Preferred Stock.

     4.   Liquidation.  Upon the dissolution or liquidation of the Corporation,
          -----------
whether voluntary or involuntary, holders of Common Stock will be entitled to
receive all assets of the Corporation available for distribution to its
stockholders, subject to any preferential rights of any then outstanding
Preferred Stock.

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B.   PREFERRED STOCK.
     ---------------

     Preferred Stock may be issued from time to time in one or more series, each
of such series to have such terms as stated or expressed herein and in the
resolution or resolutions providing for the issue of such series adopted by the
Board of Directors of the Corporation as hereinafter provided.  Any shares of
Preferred Stock which may be redeemed, purchased or acquired by the Corporation
may be reissued except as otherwise provided by law.  Different series of
Preferred Stock shall not be construed to constitute different classes of shares
for the purposes of voting by classes unless expressly provided.

     Authority is hereby expressly granted to the Board of Directors from time
to time to issue the Preferred Stock in one or more series, and in connection
with the creation of any such series, by resolution or resolutions providing for
the issue of the shares thereof, to determine and fix such voting powers, full
or limited, or no voting powers, and such designations, preferences and relative
participating, optional or other special rights, and qualifications, limitations
or restrictions thereof, including without limitation thereof, dividend rights,
conversion rights, redemption privileges and liquidation preferences, as shall
be stated and expressed in such resolutions, all to the full extent now or
hereafter permitted by the General Corporation Law of Delaware.  Without
limiting the generality of the foregoing, the resolutions providing for issuance
of any series of Preferred Stock may provide that such series shall be superior
or rank equally or be junior to the Preferred Stock of any other series to the
extent permitted by law. Except as otherwise provided in this Certificate of
Incorporation, no vote of the holders of the Preferred Stock or Common Stock
shall be a prerequisite to the designation or issuance of any shares of any
series of the Preferred Stock authorized by and complying with the conditions of
this Certificate of Incorporation, the right to have such vote being expressly
waived by all present and future holders of the capital stock of the
Corporation.

     FIFTH.  The Corporation shall have a perpetual existence.

     SIXTH.  In furtherance of and not in limitation of powers conferred by
statute, it is further provided that the Board of Directors is expressly
authorized to adopt, amend or repeal the By-Laws of the Corporation.

     SEVENTH.  Except to the extent that the General Corporation Law of Delaware
prohibits the elimination or limitation of liability of directors for breaches
of fiduciary duty, no director of the Corporation shall be personally liable to
the Corporation or its stockholders for monetary damages for any breach of
fiduciary duty as a director, notwithstanding any provision of law imposing such
liability.  No amendment to or repeal of this provision shall apply to or have
any effect on the liability or alleged liability of any director of the
Corporation for or with respect to any acts or omissions of such director
occurring prior to such amendment.

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     EIGHTH.  1.  Actions, Suits and Proceedings Other than by or in the Right
                  ------------------------------------------------------------
of the Corporation.  The Corporation shall indemnify each person who was or is a
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party or is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding, whether civil, criminal, administrative or
investigative (other than an action by or in the right of the Corporation), by
reason of the fact that he is or was, or has agreed to become, a director or
officer of the Corporation, or is or was serving, or has agreed to serve, at the
request of the Corporation, as a director, officer or trustee of, or in a
similar capacity with, another corporation, partnership, joint venture, trust or
other enterprise (including any employee benefit plan) (all such persons being
referred to hereafter as an "Indemnitee"), or by reason of any action alleged to
have been taken or omitted in such capacity, against all expenses (including
attorneys' fees), judgments, fines and amounts paid in settlement actually and
reasonably incurred by him or on his behalf in connection with such action, suit
or proceeding and any appeal therefrom, if he acted in good faith and in a
manner he reasonably believed to be in, or not opposed to, the best interests of
the Corporation, and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his conduct was unlawful.  The termination of any
action, suit or proceeding by judgment, order, settlement, conviction or upon a
plea of nolo contendere or its equivalent, shall not, of itself, create a
        ---------------
presumption that the person did not act in good faith and in a manner which he
reasonably believed to be in, or not opposed to, the best interests of the
Corporation, and, with respect to any criminal action or proceeding, had
reasonable cause to believe that his conduct was unlawful. Notwithstanding
anything to the contrary in this Article, except as set forth in Section 7
below, the Corporation shall not indemnify an Indemnitee seeking indemnification
in connection with a proceeding (or part thereof) initiated by the Indemnitee
unless the initiation thereof was approved by the Board of Directors of the
Corporation. Notwithstanding anything to the contrary in this Article, the
Corporation shall not indemnify an Indemnitee to the extent such Indemnitee is
reimbursed from the proceeds of insurance, and in the event the Corporation
makes any indemnification payments to an Indemnitee and such Indemnitee is
subsequently reimbursed from the proceeds of insurance, such Indemnitee shall
promptly refund such indemnification payments to the Corporation to the extent
of such insurance reimbursement.

     2.   Actions or Suits by or in the Right of the Corporation.  The
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Corporation shall indemnify any Indemnitee who was or is a party or is
threatened to be made a party to any threatened, pending or completed action or
suit by or in the right of the Corporation to procure a judgment in its favor by
reason of the fact that he is or was, or has agreed to become, a director or
officer of the Corporation, or is or was serving, or has agreed to serve, at the
request of the Corporation, as a director, officer or trustee of, or in a
similar capacity with, another corporation, partnership, joint venture, trust or
other enterprise (including any employee benefit plan), or by reason of any
action alleged to have been taken or omitted in such capacity, against all
expenses (including attorneys' fees) and, to the extent permitted by law,
amounts paid in settlement actually and reasonably incurred by him or on his
behalf in connection with such action, suit or proceeding and any appeal
therefrom,

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if he acted in good faith and in a manner he reasonably believed to be in, or
not opposed to, the best interests of the Corporation, except that no
indemnification shall be made in respect of any claim, issue or matter as to
which such person shall have been adjudged to be liable to the Corporation
unless and only to the extent that the Court of Chancery of Delaware shall
determine upon application that, despite the adjudication of such liability but
in view of all the circumstances of the case, such person is fairly and
reasonably entitled to indemnity for such expenses (including attorneys' fees)
which the Court of Chancery of Delaware shall deem proper.

     3.   Indemnification for Expenses of Successful Party.  Notwithstanding the
          ------------------------------------------------
other provisions of this Article, to the extent that an Indemnitee has been
successful, on the merits or otherwise, in defense of any action, suit or
proceeding referred to in Sections 1 and 2 of this Article, or in defense of any
claim, issue or matter therein, or on appeal from any such action, suit or
proceeding, he shall be indemnified against all expenses (including attorneys'
fees) actually and reasonably incurred by him or on his behalf in connection
therewith.  Without limiting the foregoing, if any action, suit or proceeding is
disposed of, on the merits or otherwise (including a disposition without
prejudice), without (i) the disposition being adverse to the Indemnitee, (ii) an
adjudication that the Indemnitee was liable to the Corporation, (iii) a plea of
guilty or nolo contendere by the Indemnitee, (iv) an adjudication that the
          ---------------
Indemnitee did not act in good faith and in a manner he reasonably believed to
be in or not opposed to the best interests of the Corporation, and (v) with
respect to any criminal proceeding, an adjudication that the Indemnitee had
reasonable cause to believe his conduct was unlawful, the Indemnitee shall be
considered for the purposes hereof to have been wholly successful with respect
thereto.

     4.   Notification and Defense of Claim.  As a condition precedent to his
          ---------------------------------
right to be indemnified, the Indemnitee must notify the Corporation in writing
as soon as practicable of any action, suit, proceeding or investigation
involving him for which indemnity will or could be sought.  With respect to any
action, suit, proceeding or investigation of which the Corporation is so
notified, the Corporation will be entitled to participate therein at its own
expense and/or to assume the defense thereof at its own expense, with legal
counsel reasonably acceptable to the Indemnitee.  After notice from the
Corporation to the Indemnitee of its election so to assume such defense, the
Corporation shall not be liable to the Indemnitee for any legal or other
expenses subsequently incurred by the Indemnitee in connection with such claim,
other than as provided below in this Section 4.  The Indemnitee shall have the
right to employ his own counsel in connection with such claim, but the fees and
expenses of such counsel incurred after notice from the Corporation of its
assumption of the defense thereof shall be at the expense of the Indemnitee
unless (i) the employment of counsel by the Indemnitee has been authorized by
the Corporation, (ii) counsel to the Indemnitee shall have reasonably concluded
that there may be a conflict of interest or position on any significant issue
between the Corporation and the Indemnitee in the conduct of the defense of such
action or (iii) the Corporation shall not in fact have employed counsel to
assume the defense of such action, in each of which cases the fees and expenses
of counsel for the

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Indemnitee shall be at the expense of the Corporation, except as otherwise
expressly provided by this Article. The Corporation shall not be entitled,
without the consent of the Indemnitee, to assume the defense of any claim
brought by or in the right of the Corporation or as to which counsel for the
Indemnitee shall have reasonably made the conclusion provided for in clause (ii)
above.

     5.   Advance of Expenses.  Subject to the provisions of Section 6 below, in
          -------------------
the event that the Corporation does not assume the defense pursuant to Section 4
of this Article of any action, suit, proceeding or investigation of which the
Corporation receives notice under this Article, any expenses (including
attorneys' fees) incurred by an Indemnitee in defending a civil or criminal
action, suit, proceeding or investigation or any appeal therefrom shall be paid
by the Corporation in advance of the final disposition of such matter; provided,
however, that the payment of such expenses incurred by an Indemnitee in advance
of the final disposition of such matter shall be made only upon receipt of an
undertaking by or on behalf of the Indemnitee to repay all amounts so advanced
in the event that it shall ultimately be determined that the Indemnitee is not
entitled to be indemnified by the Corporation as authorized in this Article.
Such undertaking shall be accepted without reference to the financial ability of
the Indemnitee to make such repayment.

     6.   Procedure for Indemnification.  In order to obtain indemnification or
          -----------------------------
advancement of expenses pursuant to Section 1, 2, 3 or 5 of this Article, the
Indemnitee shall submit to the Corporation a written request, including in such
request such documentation and information as is reasonably available to the
Indemnitee and is reasonably necessary to determine whether and to what extent
the Indemnitee is entitled to indemnification or advancement of expenses.  Any
such indemnification or advancement of expenses shall be made promptly, and in
any event within 60 days after receipt by the Corporation of the written request
of the Indemnitee, unless with respect to requests under Section 1, 2 or 5 the
Corporation determines within such 60-day period that the Indemnitee did not
meet the applicable standard of conduct set forth in Section 1 or 2, as the case
may be.  Such determination shall be made in each instance by (a) a majority
vote of the directors of the Corporation consisting of persons who are not at
that time parties to the action, suit or proceeding in question ("disinterested
directors"), whether or not a quorum, (b) a majority vote of a committee of
disinterested directors designated by majority vote of disinterested directors,
whether or not a quorum, (c) a majority vote of a quorum of the outstanding
shares of stock of all classes entitled to vote for directors, voting as a
single class, which quorum shall consist of stockholders who are not at that
time parties to the action, suit or proceeding in question, (d) independent
legal counsel (who may, to the extent permitted by law, be regular legal counsel
to the Corporation), or (e) a court of competent jurisdiction.

     7.   Remedies.  The right to indemnification or advances as granted by this
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Article shall be enforceable by the Indemnitee in any court of competent
jurisdiction if the Corporation denies such request, in whole or in part, or if
no disposition thereof is made within the 60-day period referred to above in
Section 6.  Unless

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otherwise required by law, the burden of proving that the Indemnitee is not
entitled to indemnification or advancement of expenses under this Article shall
be on the Corporation. Neither the failure of the Corporation to have made a
determination prior to the commencement of such action that indemnification is
proper in the circumstances because the Indemnitee has met the applicable
standard of conduct, nor an actual determination by the Corporation pursuant to
Section 6 that the Indemnitee has not met such applicable standard of conduct,
shall be a defense to the action or create a presumption that the Indemnitee has
not met the applicable standard of conduct. The Indemnitee's expenses (including
attorneys' fees) incurred in connection with successfully establishing his right
to indemnification, in whole or in part, in any such proceeding shall also be
indemnified by the Corporation.

     8.   Subsequent Amendment.  No amendment, termination or repeal of this
          --------------------
Article or of the relevant provisions of the General Corporation Law of Delaware
or any other applicable laws shall affect or diminish in any way the rights of
any Indemnitee to indemnification under the provisions hereof with respect to
any action, suit, proceeding or investigation arising out of or relating to any
actions, transactions or facts occurring prior to the final adoption of such
amendment, termination or repeal.

     9.   Other Rights.  The indemnification and advancement of expenses
          ------------
provided by this Article shall not be deemed exclusive of any other rights to
which an Indemnitee seeking indemnification or advancement of expenses may be
entitled under any law (common or statutory), agreement or vote of stockholders
or disinterested directors or otherwise, both as to action in his official
capacity and as to action in any other capacity while holding office for the
Corporation, and shall continue as to an Indemnitee who has ceased to be a
director or officer, and shall inure to the benefit of the estate, heirs,
executors and administrators of the Indemnitee.  Nothing contained in this
Article shall be deemed to prohibit, and the Corporation is specifically
authorized to enter into, agreements with officers and directors providing
indemnification rights and procedures different from those set forth in this
Article.  In addition, the Corporation may, to the extent authorized from time
to time by its Board of Directors, grant indemnification rights to other
employees or agents of the Corporation or other persons serving the Corporation
and such rights may be equivalent to, or greater or less than, those set forth
in this Article.

     10.  Partial Indemnification.  If an Indemnitee is entitled under any
          -----------------------
provision of this Article to indemnification by the Corporation for some or a
portion of the expenses (including attorneys' fees), judgments, fines or amounts
paid in settlement actually and reasonably incurred by him or on his behalf in
connection with any action, suit, proceeding or investigation and any appeal
therefrom but not, however, for the total amount thereof, the Corporation shall
nevertheless indemnify the Indemnitee for the portion of such expenses
(including attorneys' fees), judgments, fines or amounts paid in settlement to
which the Indemnitee is entitled.

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     11.  Insurance.  The Corporation may purchase and maintain insurance, at
          ---------
its expense, to protect itself and any director, officer, employee or agent of
the Corporation or another corporation, partnership, joint venture, trust or
other enterprise (including any employee benefit plan) against any expense,
liability or loss incurred by him in any such capacity, or arising out of his
status as such, whether or not the Corporation would have the power to indemnify
such person against such expense, liability or loss under the General
Corporation Law of Delaware.

     12.  Merger or Consolidation.  If the Corporation is merged into or
          -----------------------
consolidated with another corporation and the Corporation is not the surviving
corporation, the surviving corporation shall assume the obligations of the
Corporation under this Article with respect to any action, suit, proceeding or
investigation arising out of or relating to any actions, transactions or facts
occurring prior to the date of such merger or consolidation.

     13.  Savings Clause.  If this Article or any portion hereof shall be
          --------------
invalidated on any ground by any court of competent jurisdiction, then the
Corporation shall nevertheless indemnify each Indemnitee as to any expenses
(including attorneys' fees), judgments, fines and amounts paid in settlement in
connection with any action, suit, proceeding or investigation, whether civil,
criminal or administrative, including an action by or in the right of the
Corporation, to the fullest extent permitted by any applicable portion of this
Article that shall not have been invalidated and to the fullest extent permitted
by applicable law.

     14.  Definitions.  Terms used herein and defined in Section 145(h) and
          -----------
Section 145(i) of the General Corporation Law of Delaware shall have the
respective meanings assigned to such terms in such Section 145(h) and Section
145(i).

     15.  Subsequent Legislation.  If the General Corporation Law of Delaware is
          ----------------------
amended after adoption of this Article to expand further the indemnification
permitted to Indemnitees, then the Corporation shall indemnify such persons to
the fullest extent permitted by the General Corporation Law of Delaware, as so
amended.

     NINTH.  The Corporation reserves the right to amend, alter, change or
repeal any provision contained in this Certificate of Incorporation, in the
manner now or hereafter prescribed by statute and this Certificate of
Incorporation, and all rights conferred upon stockholders herein are granted
subject to this reservation.

     TENTH.  This Article is inserted for the management of the business and for
the conduct of the affairs of the Corporation.

     1.   Number of Directors.  The number of directors of the Corporation shall
          -------------------
not be less than three.  The exact number of directors within the limitations
specified in the preceding sentence shall be fixed from time to time by, or in
the manner provided in, the Corporation's By-Laws.

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     2.   Classes of Directors.  The Board of Directors shall be and is divided
          --------------------
into three classes:  Class I, Class II and Class III.  No one class shall have
more than one director more than any other class.  If a fraction is contained in
the quotient arrived at by dividing the designated number of directors by three,
then, if such fraction is one-third, the extra director shall be a member of
Class I, and if such fraction is two-thirds, one of the extra directors shall be
a member of Class I and one of the extra directors shall be a member of Class
II, unless otherwise provided from time to time by resolution adopted by the
Board of Directors.

     3.   Election of Directors.  Elections of directors need not be by written
          ---------------------
ballot except as and to the extent provided in the By-Laws of the Corporation.

     4.   Terms of Office.  Each director shall serve for a term ending on the
          ---------------
date of the third annual meeting following the annual meeting at which such
director was elected; provided, that each initial director in Class I shall
serve for a term ending on the date of the annual meeting in 2000; each initial
director in Class II shall serve for a term ending on the date of the annual
meeting in 2001; and each initial director in Class III shall serve for a term
ending on the date of the annual meeting in 2002; and provided further, that the
term of each director shall be subject to the election and qualification of his
successor and to his earlier death, resignation or removal.

     5.   Allocation of Directors Among Classes in the Event of Increases or
          ------------------------------------------------------------------
Decreases in the Number of Directors.  In the event of any increase or decrease
------------------------------------
in the authorized number of directors, (i) each director then serving as such
shall nevertheless continue as a director of the class of which he is a member
and (ii) the newly created or eliminated directorships resulting from such
increase or decrease shall be apportioned by the Board of Directors among the
three classes of directors so as to ensure that no one class has more than one
director more than any other class.  To the extent possible, consistent with the
foregoing rule, any newly created directorships shall be added to those classes
whose terms of office are to expire at the latest dates following such
allocation, and any newly eliminated directorships shall be subtracted from
those classes whose terms of offices are to expire at the earliest dates
following such allocation, unless otherwise provided from time to time by
resolution adopted by the Board of Directors.

     6.   Quorum; Action at Meeting.  A majority of the directors at any time in
          -------------------------
office shall constitute a quorum for the transaction of business.  In the event
one or more of the directors shall be disqualified to vote at any meeting, then
the required quorum shall be reduced by one for each director so disqualified,
provided that in no case shall less than one-third of the number of directors
fixed pursuant to Section 1 above constitute a quorum.  If at any meeting of the
Board of Directors there shall be less than such a quorum, a majority of those
present may adjourn the meeting from time to time. Every act or decision done or
made by a majority of the directors present at a meeting duly held at which a
quorum is present shall be regarded as the act of the Board of Directors unless
a greater number is required by law, by the By-Laws of the Corporation or by
this Certificate of Incorporation.

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     7.   Removal.  Directors of the Corporation may be removed only for cause
          -------
by the affirmative vote of the holders of at least two-thirds of the shares of
the capital stock of the Corporation issued and outstanding and entitled to
vote.

     8.   Vacancies.  Any vacancy in the Board of Directors, however occurring,
          ---------
including a vacancy resulting from an enlargement of the size of the Board of
Directors, shall be filled only by a vote of a majority of the directors then in
office, although less than a quorum, or by a sole remaining director.  A
director elected to fill a vacancy shall be elected for the unexpired term of
his predecessor in office, and a director chosen to fill a position resulting
from an increase in the number of directors shall hold office until the next
election of the class for which such director shall have been chosen, subject to
the election and qualification of his successor and to his earlier death,
resignation or removal.

     9.   Stockholder Nominations and Introduction of Business, Etc.  Advance
          ---------------------------------------------------------
notice of stockholder nominations for election of directors and other business
to be brought by stockholders before a meeting of stockholders shall be given in
the manner provided by the By-Laws of the Corporation.

     10.  Amendments to Article.  Notwithstanding any other provisions of law,
          ---------------------
this Certificate of Incorporation or the By-Laws of the Corporation, and
notwithstanding the fact that a lesser percentage may be specified by law, the
affirmative vote of the holders of at least sixty-six and two-thirds percent
(66 2/3%) of the shares of capital stock of the Corporation issued and
outstanding and entitled to vote shall be required to amend or repeal, or to
adopt any provision inconsistent with, this Article TENTH.

     ELEVENTH.  Stockholders of the Corporation may not take any action by
written consent in lieu of a meeting.  Notwithstanding any other provisions of
law, this Certificate of Incorporation or the By-Laws of the Corporation, and
notwithstanding the fact that a lesser percentage may be specified by law, the
affirmative vote of the holders of at least sixty-six and two-thirds percent
(66 2/3%) of the shares of capital stock of the Corporation issued and
outstanding and entitled to vote shall be required to amend or repeal, or to
adopt any provision inconsistent with, this Article ELEVENTH.

     TWELFTH.  Special meetings of stockholders may be called at any time by
only the Chairman of the Board of Directors, the President or the Board of
Directors. Business transacted at any special meeting of stockholders shall be
limited to matters relating to the purpose or purposes stated in the notice of
meeting.  Notwithstanding any other provision of law, this Certificate of
Incorporation or the By-Laws of the Corporation, and notwithstanding the fact
that a lesser percentage may be specified by law, the affirmative vote of the
holders of at least sixty-six and two-thirds percent (66 2/3%) of the shares of
capital stock of the Corporation issued and outstanding and entitled to vote
shall be required to amend or repeal, or to adopt any provision inconsistent
with, this Article TWELFTH.

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     IN WITNESS WHEREOF, the Corporation has caused this Amended and Restated
Certificate of Incorporation to be signed by its President this      day of
                                                                ----
                    , 1999.
--------------------

                              SYCAMORE NETWORKS, INC.


                              -----------------------
                              Daniel E. Smith
                              President

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