Exhibit 10.01

                                                                  March 29, 2002

Michael D. Greenbaum
Hybrid Networks, Inc.
6409 Guadalupe Mines Road
San Jose, CA  95120

Dear Michael,

This Letter  Agreement will confirm that in connection with and in consideration
of your continued  employment with Hybrid Networks,  Inc.  ("Hybrid") Hybrid and
you agree as follows:

1. At Hybrid's  request you will remain employed by Hybrid for up to ninety (90)
days following the date hereof,  provided that Hybrid  continues to pay you your
current  base  salary at its  regular  periodic  payroll  dates (the  "Retention
Period");

2.  You  will  receive  a  Severance  Payment  of  $13,541.00,  (the  "Severance
Payment"),  which is equal to two weeks of your regular base salary, as provided
in paragraph 1 of the Release;

3. You will receive a Retention  Bonus of $162,492.00,  (the "Retention  Bonus")
which is equal to six  months of your  regular  salary,  payable  upon  Hybrid's
receipt  of a  signed  copy of a  release  and a  signed  copy  of  this  Letter
Agreement.  The  Retention  Bonus will be  returned by you to the Company if you
voluntarily  terminate your employment with the Company before the expiration of
the Retention Period; and

Please acknowledge your acceptance of this Letter Agreement by signing below and
returning this letter to me as soon as possible.


Sincerely,


James R. Flach
Chairman of the Board


I have reviewed the above Letter Agreement and understand and agree to the terms
under which I will be continue to be employed with Hybrid Networks, Inc.


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Date                                Michael D. Greenbaum