**EXHIBIT
        10.55**


**STOCK
      UNIT AGREEMENT**




**STOCK
      UNIT AGREEMENT** (“Agreement”)
      effective as of September 8, 2008 (“Grant Date”), by and between AboveNet, Inc.
      (the “Company”) and Rajiv Datta (the “Participant”).




**WHEREAS,** the
      Company believes it desirable that the Participant be provided additional
      incentive to advance the interests of the Company through a grant of stock
      units
      under the AboveNet, Inc. 2008 Equity Incentive Plan (the “Plan”);




**NOW,
      THEREFORE,** the
      parties agree as follows:




**1.**  **Grant
      of Stock Units.**




Pursuant
      to the Plan and on the terms and subject to the conditions set forth herein
      and
      therein, the Company hereby grants to the Participant 35,000 stock units (the
      “Stock Units”). Each Stock Unit constitutes a right to receive from the Company
      one share (each a “Unit Share” and collectively the “Unit Shares”) of the
      Company’s Common Stock, $.01 par value per share (the “Common Stock”), subject
      to adjustment as provided in the Plan. Capitalized terms that are not defined
      in
      this Agreement shall have the respective meanings given in the Plan.




**2.**  **Vesting;
      Delivery of Unit Shares.**




The
      Stock
      Units vest ( i.e. ,
      are not
      subject to forfeiture) as follows: (a) 30% of the Stock Units shall vest on
      the
      first anniversary of the Grant Date and the underlying Unit Shares shall be
      delivered to the Participant on November 16, 2009; (b) 10% of the Stock Units
      shall vest on the second anniversary of the Grant Date and the underlying Unit
      Shares shall be delivered on November 15, 2010; and (c) 60% of the Stock Units
      shall vest on the third anniversary of the Grant Date and be delivered on
      November 15, 2011. The Stock Units are subject to earlier vesting as set forth
      in Sections 4(a), 4(b), 4(d) and 4(e). The Unit Shares are subject to earlier
      delivery only as set forth in Section 4(a) (death) and Section 4(e) (Change
      of
      Control).




**3.**  **Withholding.**




The
      Company’s obligation to deliver Unit Shares under this Agreement shall be
      subject to the payment by the Participant of any applicable federal, state
      and
      local withholding tax. The Company shall, to the extent permitted by law, have
      the right to deduct from any payment of any kind otherwise due to the
      Participant any federal, state or local taxes required to be withheld with
      respect to the vesting of the Stock Units or the delivery of the Unit Shares.




**4.**  **Termination
      of Employment; Change of Control.**




(a)  In
      the
      event of the Participant’s death prior to the vesting of all Stock Units granted
      under this Agreement or prior to delivery of all Unit Shares after vesting
      has
      occurred, any unvested Stock Units, if any, shall immediately vest and the
      underlying Unit Shares shall be immediately delivered to the Participant’s
      beneficiary or beneficiaries.









(b)  Upon
      the
      termination of Participant’s Continuous Service with the Company as a result of
      a Disability, any unvested Stock Units shall immediately vest.




(c)  In
      the
      event of the termination of the Participant’s Continuous Service by the Company
      for Cause or by the Participant other than for Good Reason, any unvested Stock
      Units shall immediately be forfeited.




(d)  Upon
      the
      termination of the Participant’s Continuous Service by the Company without Cause
      or by the Employee for Good Reason, any unvested Stock Units shall immediately
      vest.




(e)  In
      the
      event of a Change of Control, any unvested Stock Units shall immediately vest
      and the underlying Unit Shares of all vested Stock Units shall be immediately
      delivered to the Participant.




(f)  The
      parties may not accelerate the delivery of any Stock Units before the dates
      set forth above.




**5.**  **Transfer
      of Stock Units; Limitations on Delivery of Unit Shares; Put
      Right.**




(a)  The
      Stock
      Units are not transferable otherwise than by will or the laws of descent and
      distribution. Any attempt to transfer the Stock Units in contravention of this
      subparagraph (a) is void ab
      initio .
      The
      Stock Units shall not be subject to execution, attachment or other
      process.




(b)  In
      the
      event that on the date of delivery, any of the following shall be true (1)
      the
      Unit Shares may not be sold by the Participant at such time under Rule 144
      of
      the Securities Act of 1933, as amended (the “Securities Act”), or pursuant to a
      currently effective registration statement under the Securities Act, (2) the
      Participant is unable to sell the stock underlying his Unit Shares due to any
      Company imposed trading restriction or the Participant otherwise is in
      possession of material, non-public information regarding the Company or its
      securities or (3) the Company’s shares are not listed on a national stock
      exchange, the Company shall be obligated, following notice from the Participant
      as provided below, to repurchase such number of Unit Shares at the Fair Market
      Value of the Unit Shares on the date of such repurchase as required to meet
      the
      Company’s required minimum tax withholding with respect to the delivered Unit
      Shares (based on minimum statutory withholding rates for federal, state and
      local purposes, including payroll taxes, that are applicable to such
      supplemental taxable income). Notwithstanding the immediately preceding
      sentence, in the event the Internal Revenue Service determines that the fair
      market value of the Unit Shares is greater than the Fair Market Value as
      determined under the Plan and the Participant has incurred additional liability
      for income taxes, the Fair Market Value for purposes of this subparagraph (b)
      shall be increased to the value determined by the Internal Revenue Service.
      The
      Participant must give his notice to the Company of his election to exercise
      the
      right to require the Company to repurchase a portion of the Unit Shares not
      less
      than two (2) business days before the delivery date. In the event such
      Participant does not exercise such right, he shall be deemed to have elected
      to
      forego such right.




2




**6.**  **No
      Rights in Unit Shares.**




The
      Participant shall have none of the rights of a shareholder with respect to
      particular Unit Shares unless and until such Unit Shares are issued and
      delivered to him under this Agreement.




**7.**  **No
      Right to Employment.**




Nothing
      contained herein shall be deemed to confer upon the Participant any right to
      remain as an employee of the Company. The Company reserves the right to dismiss
      the Participant free from any liability hereunder, or any claim under the Plan,
      except as specifically provided in this Agreement.




**8.**  **Governing
      Law/Jurisdiction.**




This
      Agreement shall be governed by and construed in accordance with the laws of
      the
      State of New York without reference to principles of conflict of
      laws.




**9.**  **Miscellaneous.**




This
      Agreement cannot be changed or terminated orally. The Company at any time,
      and
      from time to time, may amend the terms of this Agreement; *provided,
      however,* that the
      rights under this Agreement shall not be impaired by any such amendment unless
      (i) the Company requests the consent of the Participant and (ii) the Participant
      consents in writing. This Agreement and the Plan contain the entire agreement
      between the parties relating to the subject matter hereof. In the event of
      any
      conflict between the provisions of this Agreement and those of the Plan, the
      provisions of the Plan shall control. The paragraph headings herein are intended
      for reference only and shall not affect the interpretation hereof.




**IN
      WITNESS WHEREOF,**the
      parties have executed this Agreement as of the day and year first above
      written.




/s/ Rajiv
              DattaRajiv
                DattaParticipant**ABOVENET,
                INC.**By:
            /s/
                Robert SokotaName:
                Robert
                SokotaTitle:
                SVP
                and General Counsel





3