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                                                               Exhibit 10.13b

                             AGREEMENT OF SUBLEASE

      AGREEMENT OF SUBLEASE (this "Agreement") made and entered into as of this
28th day of April, 1999 by and between Northern Telecom Inc., a Texas
corporation having an office and place of business at 2221 Lakeside Blvd.
Richardson Texas 75082 (hereinafter referred to as "Sublandlord") and ELASTIC
NETWORKS, INC. having an office and principal place of business at 6120 Windward
parkway, Suite 100, Alpharetta, GA 30005, (hereinafter referred to as
"Subtenant").

                                  WITNESSETH:

            WHEREAS, by a certain lease agreement dated April 15, 1998, said
lease, attached hereto as Exhibit "A", (hereinafter referred to as "Master
Lease"), Backman, L.C., a Georgia Limited Liability Company (hereinafter
referred to as "Landlord"), leased to Sublandlord those certain premises
consisting of approximately 13,768 square feet of rentable area known as Suites
100 & 140 (hereinafter collectively referred to as the "Premises") situated in
that certain building located at 6120 Windward Parkway in the city of
Alpharetta, Fulton County, Georgia 30004 (the "Building"), located in a business
park called Rubicon in Windward (the "Project").

            WHEREAS, Subtenant desires to sublease and hire from Sublandlord,
and Sublandlord is willing to sublet to Subtenant the Premises so mentioned in
the above paragraph.

            NOW, THEREFORE, in consideration of the mutual covenants, conditions
and agreements herein contained, Sublandlord and Subtenant agrees as follows:

      1. Sublease.

            Sublandlord, for and consideration of the rents and covenants
specified to be paid, performed and observed by Subtenant, does hereby let,
sublet, lease and demise to Subtenant the aforementioned Premises for the term
and according to the covenants and conditions contained therein. Sublandlord
represents and warrants to Subtenant that this Agreement and the term thereof is
permitted under the terms of the Master Lease, but is subject to the written
approval and consent of Landlord as set forth in Section 9 of the Master Lease.

2. Term.

            The term of this Sublease shall be for the period commencing on
April 30, 1999, and ending upon the Termination Date set forth in the Master
Lease.
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3. Rent.

      Subtenant shall pay to Landlord as rent for the Premises in advance on the
first day of each calendar month of the term of this Sublease without
deductions, offset, prior notice or demand, in lawful money of the United States
the sum set forth as rental in the Master Lease. If the commencement date is not
the first of the month, or if the Sublease termination date is not the last day
of the month, a prorated monthly installment shall be paid at the then current
rate for the fractional month during which the Sublease commences and/or
terminates. Payment of such rent shall be made to Landlord at the address set
forth in the Master Lease or at such other place as Landlord may designate in
writing, without any offset or deductions whatsoever.

4. Compliance with Master Leases.

            A. Subtenant acknowledges and agrees that this Agreement is subject
and subordinate to the terms and conditions contained in the Master Lease.
Subtenant agrees that, during the term hereof, it will observe and perform each
and all of the covenants, conditions, obligations and agreements of Tenant under
the Master Lease, with each reference therein to Landlord and Tenant, except as
otherwise provided in Section 3 hereof for payment of rent, to be deemed to
refer to Sublandlord and Subtenant and along with all of the following
paragraphs set out in this Sublease, shall be the complete terms and conditions
of this Sublease.

            B. Sublandlord represents and warrants that Exhibit "A" is a true
and complete copy of the Master Lease, the provisions of which are incorporated
by reference into this Sublease with the same effect as if entirely rewritten
herein, including all amendments thereto, if any, which have been executed to
date and that, to Sublandlord's knowledge, no default under the Master Lease
exists and no event has occurred and no condition exists, which after the
passage of time (after notice required by the Master Lease, if any) would
constitute an event of default under the applicable document or would entitle
Landlord to terminate the Master Lease under its terms or would cause, without
any further action of Landlord, the termination of the Master Lease or would
entitle Landlord to depose Sublandlord from the Premises. In the event of the
cancellation or termination of the Master Lease, for any reason whatsoever, this
Agreement shall thereupon be simultaneously canceled without any liability by
Landlord or Sublandlord to Subtenant.

            C. In the event there shall be any conflict between the provisions
of this Agreement and the provisions of the Master Lease, the Master Lease shall
prevail and control with respect to the obligations and rights of Sublandlord
and Subtenant as between the two parties.

5. Notices.

            All notices or demands of any kind required or desired to be given
by


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Sublandlord or Subtenant hereunder shall be in writing by: (a) prepaid
commercial carrier regularly providing overnight service (e.g., Federal
Express), or (b) by United States certified or registered mail, postage prepaid,
return receipt requested, or (c) by facsimile transmission addressed to the
Sublandlord, or Subtenant, respectively, at the address first above written or
to other such place as may be directed in writing one to the other. All rent and
other payments due under this Sublease or the Master Lease shall be made to
Landlord at the same address or at any other address Landlord may designate.

6. Subordination of Sublease.

            This Sublease is subject to and subordinate in all respects to the
Master Lease. Subtenant acknowledges that it has received a copy of the Master
Lease.

7. Assignment and Subletting.

            Subtenant shall not assign this sublease, or sublease the Premises
or any portion thereof hereby demised, nor suffer or permit it to be assigned by
operation of law or otherwise, nor shall the Subtenant, without the prior
written consent of Sublandlord, let or underlet or permit the said Premises or
any part thereof to be used by others for hire.

8. Indemnity.

            Sublandlord and Subtenant agree to indemnify and hold the other
party harmless from and against any and all losses, damages, claims, suits,
actions or judgments and expenses (including reasonable attorneys fees) which
may arise or grow out of bodily injury or death or damages to tangible property,
arising out of the negligence or willful misconduct of the indemnifying party,
its employees or agents.

9. Damages.

            Notwithstanding anything herein to the contrary, Sublandlord shall
not be liable to Subtenant or any party claiming through Subtenant for any
incidental, specials or consequential damages.

10. Default by Subtenant.

            Upon the breach of any of the terms, conditions or covenants of the
Master Lease or upon the failure of Subtenant to pay rent or comply with any of
the provisions of this Sublease Agreement, Sublandlord may exercise any and all
rights and remedies granted to Landlord by the Master Lease. In the event that
Subtenant breaches any of the terms, conditions, or covenants of this Sublease
or of the Master Lease and fails to remedy such breach within ten (10) days of
written notice, Sublandlord has the right, but not the obligation, to cure such
breach and bill Subtenant for the costs incurred thereby, which


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costs Subtenant shall pay to Sublandlord upon demand.

11. Miscellaneous.

            Sublandlord, to the best of its knowledge, is not aware of the
existence of any defaults by the Landlord under the Master Lease. All
warranties, representations and agreements of Subtenant herein shall also inure
to the benefit of Landlord, and Landlord is deemed a third party beneficiary of
this Sublease. Sublandlord and Subtenant acknowledged for the benefit of
Landlord that this document constitutes their full agreement with respect to the
subject matter herein.

            Subtenant agrees that, within seven days after the effective date of
this Sublease, Subtenant will provide written proof to Sublandlord that
Subtenant has in force all insurance coverage that Subtenant is required to
maintain under the provisions of the Master Lease.

            IN WITNESS WHEREOF, the parties hereto have hereunto set their hands
and seals the day and year first above written.

SUBLANDLORD:                                            SUBTENANT:
NORTHERN TELECOM INC.                                   ELASTIC NETWORKS, INC.


By: /s/ Carol Korney                                    By: /s/ Lynn Egan
    --------------------                                    --------------------
Its:                                                    Its: Assistant Secretary
    --------------------                                     -------------------
Date: 4-29-99                                           Date: 4-29-99
     -------------------                                     -------------------

        Carol Korney
        Senior Manager, Asset Management Americas


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                               CONSENT OF LANDLORD

      This subletting is hereby consented to and approved. Sublandlord hereby
agrees that approval of this consent of subletting shall not release Tenant of
its obligations under the terms of the Master Lease.

                LANDLORD:
                BACKMAN, L.C.


                By: /s/ Garett Backman
                    ------------------
                      Garett Backman

                Its: Member


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