Exhibit 10.1

AVICI SYSTEMS INC.

AMENDED AND RESTATED 1997 STOCK INCENTIVE PLAN



|1. | Purpose
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The purpose of this Amended and Restated
1997 Stock Incentive Plan (the Plan) of Avici Systems Inc., a Delaware corporation (the Company), is to advance the interests of the Companys stockholders by enhancing the Companys ability to attract, retain and
motivate persons who make (or are expected to make) important contributions to the Company by providing such persons with equity ownership opportunities and performance-based incentives and thereby better aligning the interests of such persons with
those of the Companys stockholders. Except where the context otherwise requires, the term Company shall include any present or future subsidiary corporations of Avici Systems Inc. as defined in Section 424(f) of the Internal
Revenue Code of 1986, as amended, and any regulations promulgated thereunder (the Code).



|2. | Eligibility
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All of the Companys employees,
officers, directors, consultants and advisors are eligible to be granted options, restricted stock, or other stock-based awards (each, an Award) under the Plan. Any person who has been granted an Award under the Plan shall be deemed a
Participant.



|3. | Administration, Delegation
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(a) Administration
by Board of Directors. The Plan will be administered by the Board of Directors of the Company (the Board). The Board shall have authority to grant Awards and to adopt, amend and repeal such administrative rules, guidelines and
practices relating to the Plan as it shall deem advisable. The Board may correct any defect, supply any omission or reconcile any inconsistency in the Plan or any Award in the manner and to the extent it shall deem expedient to carry the Plan into
effect and it shall be the sole and final judge of such expediency. All decisions by the Board shall be made in the Boards sole discretion and shall be final and binding on all persons having or claiming any interest in the Plan or in any
Award. No director or person acting pursuant to the authority delegated by the Board shall be liable for any action or determination relating to or under the Plan made in good faith.

(b) Delegation to Executive Officers. To the extent permitted by applicable law, the Board may delegate to one or more executive officers of the
Company the power to make Awards and exercise such other powers under the Plan as the Board may determine, provided that the Board shall fix the maximum number of shares subject to Awards and the maximum number of shares for any one Participant to
be made by such executive officers.

(c) Appointment of Committees. To the extent permitted by applicable law, the Board may
delegate any or all of its powers under the Plan to one or more committees or subcommittees of the Board (a Committee). If and when the common stock, $.0001 par value per share, of the Company (the Common Stock) is registered
under the Securities Exchange Act of 1934 (the Exchange Act), the Board shall appoint one such Committee of not less than two members, each member of which shall be an outside director within the meaning of
Section 162(m) of the Code and a Non-Employee director as defined in Rule 16b-3 promulgated under the Exchange Act. All references in the Plan to the Board shall mean the Board or a Committee of the Board or the
executive officer referred to in Section 3(b) to the extent that the Boards powers or authority under the Plan have been delegated to such Committee or executive officer.



|4. | Stock Available for Awards
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(a) Number of
Shares. Subject to adjustment under Section 4(c), Awards may be made under the Plan for up to 1,796,031 shares of Common Stock. If any Award expires or is terminated, surrendered or canceled without having been fully exercised or is
forfeited in whole or in part or results in any Common Stock not being issued, the unused Common Stock covered by such Award shall again be available for the grant of Awards under the Plan, subject, however, in the case of Incentive Stock Options
(as hereinafter defined), to any limitation required under the Code. Shares issued under the Plan may consist in whole or in part of authorized but unissued shares or treasury shares.

(b) Per-Participant Limit. Subject to adjustment under Section 4(c), for Awards granted after the Common Stock is registered under the
Exchange Act, the maximum number of shares with respect to which any Award may be granted to any Participant under the Plan shall be 325,000 per calendar year. The per-participant limit described in this Section 4(b) shall be construed and
applied consistently with Section 162(m) of the Code.



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(c) Adjustment to Common Stock. In the event of any stock split, stock dividend, recapitalization,
reorganization, merger, consolidation, combination, exchange of shares, liquidation, spin-off, split-up, or other similar change in capitalization or event, or any distribution to holders of Common Stock other than a normal cash dividend
(i) the number and class of securities available under this Plan, (ii) the number and class of security and exercise price per share subject to each outstanding Option, (iii) the repurchase price per security subject to each
outstanding Restricted Stock Award, and (iv) the terms of each other outstanding stock-based Award shall be appropriately adjusted by the Board (or substituted Awards may be made), in order in the case of each outstanding Award to preserve the
economic value of the Award. If this Section 4(c) applies and Section 8(e)(1) also applies to any event, Section 8(e)(1) shall be applicable to such event, and this Section 4(c) shall not be applicable. Adjustments under this
Section 4(c) shall be mandatory and shall be final, binding and conclusive.



|5. | Stock Options
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(a) General. The Board may
grant options to purchase Common Stock (each, an Option) and determine the number of shares of Common Stock to be covered by each Option, the exercise price of each Option and the conditions and limitations applicable to the exercise of
each Option, including conditions relating to applicable federal or state securities laws, as it considers necessary or advisable. An Option which is not intended to be an Incentive Stock Option (as hereinafter defined) shall be designated a
Nonstatutory Stock Option.

(b) Incentive Stock Options. An Option that the Board intends to be an incentive stock
option as defined in Section 422 of the Code (an Incentive Stock Option) shall only be granted to employees of the Company and shall be subject to and shall be construed consistently with the requirements of Section 422
of the Code. The Company shall have no liability to a Participant, or any other, party, if an Option (or any part thereof) which is intended to be an Incentive Stock Option is not an Incentive Stock Option.

(c) Exercise Price. The Board shall establish the exercise price at the time each Option is granted and specify it in the applicable option
agreement.

(d) Duration of Options. Each Option shall be exercisable at such times and subject to such terms and conditions as the
Board may specify in the applicable option agreement. No Option will be granted for a term in excess of 10 years.

(e) Exercise of
Option. Options may be exercised only by delivery to the Company of a written notice of exercise signed by the proper person together with payment in full as specified in Section 5(f) for the number of shares for which the Option is
exercised.

(f) Payment Upon Exercise. Common Stock purchased upon the exercise of an Option granted under the Plan shall be paid
for as follows:



| | (1) | in cash or by check, payable to the order of the Company;
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| | (2) | except as the Board may otherwise provide in an Option Agreement, delivery of an irrevocable and unconditional undertaking by a creditworthy broker to deliver promptly to the
Company sufficient funds to pay the exercise price, or delivery by the Participant to the Company of a copy of irrevocable and unconditional instructions to a creditworthy broker to deliver promptly to the Company cash or a check sufficient to pay
the exercise price;
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| | (3) | to the extent permitted by the Board and explicitly provided in an Option Agreement (i) by delivery of shares of Common Stock owned by the Participant valued at their fair
market value as determined by the Board in good faith (Fair Market Value), which Common Stock was owned by the Participant at least six months prior to such delivery, (ii) by delivery of a promissory note of the Participant to the
Company on terms determined by the Board, or (iii) by payment of such other lawful consideration as the Board may determine; or
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| | (4) | any combination of the above permitted forms of payment.
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|6. | Restricted Stock
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(a) Grants. The Board may
grant Awards entitling recipients to acquire shares of Common Stock, subject to the right of the Company to repurchase all or part of such shares at their issue price or other stated or formula price (or to require forfeiture of such shares if
issued at no cost) from the recipient in the event that conditions specified by the Board in the applicable Award are not satisfied prior to the end of the applicable restriction period or periods established by the Board for such Award (each,
Restricted Stock Award).



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(b) Terms and Conditions. The Board shall determine the terms and conditions of any such
Restricted Stock Award, including the conditions for repurchase (or forfeiture) and the issue price, if any. Any stock certificates issued in respect of a Restricted Stock Award shall be registered in the name of the Participant and, unless
otherwise determined by the Board, deposited by the Participant, together with a stock power endorsed in blank, with the Company (or its designee). At the expiration of the applicable restriction periods, the Company (or such designee) shall deliver
the certificates no longer subject to such restrictions to the Participant or if the Participant has died, to the beneficiary designated, in a manner determined by the Board, by a Participant to receive amounts due or exercise rights of the
Participant in the event of the Participants death (the Designated Beneficiary). In the absence of an effective designation by a Participant, Designated Beneficiary shall mean the Participants estate.



|7. | Other Stock-Based Awards
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The Board shall have the
right to grant other Awards based upon the Common Stock having such terms and conditions as the Board may determine, including the grant of shares based upon certain conditions, the grant of securities convertible into Common Stock and the grant of
stock appreciation rights.



|8. | General Provisions Applicable to Awards
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(a)
Transferability of Awards. Except a the Board may otherwise determine or provide in an Award, Awards shall not be sold, assigned, transferred, pledged or otherwise encumbered by the person to whom they are granted, either voluntarily or by
operation of law, except by will or the laws of descent and distribution, and, during the life of the Participant, shall be exercisable only by the Participant. References to a Participant, to the extent relevant in the context, shall include
references to authorized transferees.

(b) Documentation. Each Award under the Plan shall be evidenced by a written instrument in
such form as the Board shall determine. Each Award may contain terms and conditions in addition to those set forth in the Plan.

(c)
Board Discretion. Except as otherwise provided by the Plan, each type of Award may be made alone or in addition or in relation to any other type of Award. The terms of each type of Award need not be identical, and the Board need not treat
Participants uniformly.

(d) Termination of Status. The Board shall determine the effect on an Award of the disability, death,
retirement, authorized leave of absence or other change in the employment or other status of a Participant and the extent to which, and the period during which, the Participant, the Participants legal representative, conservator, guardian or
Designated Beneficiary may exercise rights under the Award.

(e) Acquisition Events



| | (1) | Consequences of Acquisition Events. Upon the occurrence of an Acquisition Event (as defined below), or the execution by the Company of any agreement with respect to an
Acquisition Event, the Board shall take any one or more of the following actions with respect to then outstanding Awards: (i) provide that outstanding Options shall be assumed, or equivalent Options shall be substituted, by the acquiring or
succeeding corporation (or an affiliate thereof), provided that any such Options substituted for Incentive Stock Options shall satisfy, in the determination of the Board, the requirements of Section 424(a) of the Code; (ii) upon written
notice to the Participants, provide that all or a portion of then unexercised Options will become exercisable in full or in part as of a specified time (the Acceleration Time) prior to the Acquisition Event and will terminate immediately
prior to the consummation of such Acquisition Event, except to the extent exercised by the Participants between the Acceleration Time and the consummation of such Acquisition Event; (iii) in the event of an Acquisition Event under the terms of
which holders of Common Stock will receive upon consummation thereof a cash payment for each share of Common Stock surrendered pursuant to such Acquisition Event (the Acquisition Price), provide that all outstanding Options shall
terminate upon consummation of such Acquisition Event and each Participant shall receive, in exchange therefor, a cash payment equal to the amount (if any) by which (A) the Acquisition Price multiplied by the number of shares of Common Stock
subject to such outstanding Options (whether or not then exercisable), exceeds (B) the aggregate exercise price of such Options; (iv) provide that all or any portion of the Restricted Stock Awards then outstanding shall become free of all
or certain restrictions prior to the consummation of the Acquisition Event; and (v) provide that any other stock-based Awards outstanding (A) shall become exercisable, realizable or vested in full or in part, or shall be free of all or
certain conditions or restrictions, as applicable to each such Award, prior to the consummation of the Acquisition Event, or (B), if applicable, shall be assumed, or equivalent Awards shall be substituted, by the acquiring or succeeding corporation
(or an affiliate thereof).
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An Acquisition Event shall mean: (a) any merger or consolidation which results in the
voting securities of the Company outstanding immediately prior thereto representing immediately thereafter (either by remaining outstanding or by being converted into voting securities of the surviving r acquiring entity) less than 51% of the
combined voting power of the voting securities of the Company or such surviving or acquiring entity outstanding immediately after such merger or consolidation; (b) any sale of all or substantially all of the assets of the Company; or
(c) the complete liquidation of the Company.



| | (2) | Assumption of Options Upon Certain Events. The Board may grant Awards under the Plan in substitution for stock and stock-based awards held by employees of another corporation
who become employees of the Company as a result of a merger or consolidation of the employing corporation with the Company or the acquisition by the Company of property or stock of the employing corporation. The substitute Awards shall be granted on
such terms and conditions as the Board considers appropriate in the circumstances.
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(f) Withholding. Each Participant
shall pay to the Company, or make provision satisfactory to the Board for payment of, any taxes required by law to be withheld in connection with Awards to such Participant no later than the date of the event creating the tax liability. The Board
may allow Participants to satisfy such tax obligations in whole or in part in shares of Common Stock, including shares retained from the Award creating the tax obligation, valued at their Fair Market Value. The Company may, to the extent permitted
by law, deduct any such tax obligations from any payment of any kind otherwise due to a Participant.

(g) Amendment of Award. The
Board may amend, modify or terminate any outstanding Award, including but not limited to, substituting therefor another Award of the same or a different type, changing the date of exercise or realization, and converting an Incentive Stock Option to
a Nonstatutory Stock Option, provided that the Participants consent to such action shall be required unless the Board determines that the action, taking into account any related action, would not materially and adversely affect the
Participant, provided further thatno Award may be repriced by cancellation or amendment of such Award without approval of the shareholders of the Company (except pursuant to Section 4(c) or Section 8(e)) if the effect would be to
reduce the exercise price for the shares underlying such Award.

(h) Conditions on Delivery of Stock. The Company will not be
obligated to deliver any shares of Common Stock pursuant to the Plan or to remove restrictions from shares previously delivered under the Plan until (i) all conditions of the Award have been met or removed to the satisfaction of the Company,
(ii) in the opinion of the Companys counsel, all other legal matters in connection with the issuance and delivery of such shares have been satisfied, including any applicable securities laws and any applicable stock exchange or stock
market rules and regulations, and (iii) the Participant has executed and delivered to the Company such representations or agreements as the Company may consider appropriate to satisfy the requirements of any applicable laws, rules or
regulations.

(i) Acceleration. The Board may at an time provide that any Options shall become immediately exercisable in full or in
part, that any Restricted Stock Awards shall be free of all restrictions or that any other stock-based Awards may become exercisable in full or in part or free of some or all restrictions or conditions, or otherwise realizable in full or in part, as
the case may be.



|9. | Miscellaneous
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(a) No Right To Employment or
Other Status. No person shall have any claim or right to be granted an Award, and the grant of an Award shall not be construed as giving a Participant the right to continued employment or any other relationship with the Company. The Company
expressly reserves the right at any time to dismiss or otherwise terminate its relationship with a Participant free from any liability or claim under the Plan, except as expressly provided in the applicable Award.

(b) No Rights As Stockholder. Subject to the provisions of the applicable Award, no Participant or Designated Beneficiary shall have any rights as
a stockholder with respect to any shares of Common Stock to be distributed with respect to an Award until becoming the record holder of such shares.

(c) Effective Date and Term of Plan. The Plan shall become effective on the date on which it is adopted by the Board. No Awards shall be granted under the Plan after the completion of ten years from the earlier
of (i) the date on which the Plan was adopted by the Board or (ii) the date a Plan was approved by the Companys stockholders, but Awards previously granted may extend beyond that date.

(d) Amendment of Plan. The Board may amend, suspend or terminate the Plan or any portion thereof at any time.



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(e) Governing Law. The provisions of the Plan and all Awards made hereunder shall be governed by
and interpreted in accordance with the laws of the State of Delaware, without regard to any applicable conflicts of law.

Amendment and Restatement Adopted by Board of Directors

April 18, 2007

Amendment and Restatement Adopted by Stockholders

May 31, 2007

1.3:1
adjustment to the number of shares available for grant under the Plan pursuant to Section 4(c) of the Plan as determined by the Subcommittee of the Compensation Committee of the Board of Directors in connection with an extraordinary cash
dividend declared on April 22, 2007 and payable on June 22, 2007

Effective June 11, 2007