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                                                                   EXHIBIT 10.15

August 17, 1998


Rusty Cumpston
3732 Woodshadow Lane
Addison, TX  75244


Dear Rusty:

On behalf of Optical Networks Incorporated, I am pleased to offer you a position
of Vice President of Engineering.  You will be reporting directly to Hugh
Martin.

You will receive a salary of $175,000 annually, paid in equal increments on a
bi-weekly basis.  This offer includes a one-time hire on bonus of $45,000 which
will be paid to you within your first 30 days of employment with ONI.  We will
also be offering you an annual bonus of $40,000 (guaranteed for the first year
only) which will be scheduled for payment on your first anniversary with ONI.
We are willing to let you take a loan against this bonus if you purchase a home
in the area and need to use this bonus for part of the down payment.  Please
note, however, that this loan will be fully recoverable by ONI if you are to
leave our employment for any reason within the first 12 months.

We will also be granting you a stock option of 125,000 shares of common stock
with an option price of $0.36 per share.  This stock option must be approved by
our Board of Directors, which will vote on this in the next board meeting after
your start date.  The option will vest over a four-year period with the first
25% vesting upon the first anniversary of your start date and the remainder
vesting at 1/48th of the shares for each month thereafter.

We will be offering you our standard relocation package and temporary housing
for the first 60 days of employment at Oakwood Corporate Housing.  Please
contact me for further explanation of these two benefits.

We have also agreed to 2 round trip tickets between San Jose, CA and Addison, TX
to help in aiding the sale of your home there.

We will be offering you our standard benefits package that includes health,
dental, vision, term life insurance, long term disability, Section 125 and 401K
plans.

We will also be offering you 15 days of vacation per year, 10 company holidays
and up to a maximum of 10 sick days per year.  Please read through your employee
handbook closely for clarification on each of these important policies.

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Rusty Cumpston
August 17, 1998
Page 2

Your employment with ONI is for an indefinite term.  In other words, the
employment relationship is "at will," and you have the right to terminate that
employment relationship at any time for any reason.  Also, although I hope that
you will remain with us and be successful here, ONI must, and does, retain the
right to terminate the employment relationship at any time for any reason.  This
"at will" employment relationship can only be modified in writing by an
authorized officer of ONI.  This paragraph contains the entire agreement between
you and ONI regarding the right and ability of either you or ONI to terminate
your employment with ONI.

Your employment is also conditioned upon your agreement and execution of ONI's
attached Invention, Assignment and Confidentiality Agreement.  You must also
provide proof of your ability to legally work within the United States on your
first day of employment with ONI.

Please sign the bottom of this letter to accept this offer and return the
original to me.  If we do not receive back confirmation of your acceptance by
August 27, 1998 this offer will terminate.

ONI is committed to hiring employees like you that have the courage, creativity,
and experience to develop new ideas for new markets.  We look forward to your
joining us!

Sincerely,

/s/ Lisa Blos-Johnson
Lisa Blos-Johnson
Vice President of Human Resources
Optical Networks Incorporated


/s/ Rusty Cumpston 9/28/98
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Employee Acceptance/Start Date