<PAGE>

EXHIBIT 10.15e

SILICON VALLEY BANK


                         AMENDMENT TO LOAN AND SECURITY
                                    AGREEMENT

BORROWER:         SYNC RESEARCH, INC.
ADDRESS:          40 PARKER
                  IRVINE, CALIFORNIA  92618

DATED:            OCTOBER 31, 1999

         THIS AMENDMENT TO LOAN AGREEMENT is entered into between SILICON VALLEY
BANK ("Silicon") and the borrower named above (the "Borrower").

         The Parties agree to amend, effective as of the date hereof, the Loan
and Security Agreement between them, dated September 18, 1991, as amended by
that Extension Agreement dated August 3, 1992, by that Amendment to Loan
Agreement dated October 20, 1992, by that Amendment to Loan Agreement dated
August 23, 1993, by that Amendment to Loan Agreement dated February 10, 1994, by
that Amendment to Loan Agreement dated July 18, 1994, by that Amendment to Loan
Agreement dated September 20, 1994, by that Amendment to Loan and Security
Agreement dated August 31, 1995, by that Amendment to Loan and Security
Agreement (the "October 1995 Amendment") dated October 5, 1995, by that
Amendment to Loan Agreement dated July 3, 1996, by that Amendment to Loan and
Security Agreement dated October 6, 1996, by that Amendment to Loan and Security
Agreement dated June 10, 1997, by that Amendment to Loan and Security Agreement
dated as of December 3, 1997, and by that Amendment to Loan and Security
Agreement dated April 14, 1999 (as so amended and as otherwise amended from time
to time being referred to herein as the "Loan Agreement"), as follows.
(Capitalized terms used but not defined in this Agreement, shall have the
meanings set forth in the Loan Agreement.)

         1. REVISED CREDIT LIMIT. That section of the Schedule to Loan Agreement
entitled "Credit Limit (Section 1.1)" is hereby amended in its entirety to read
as follows:

     "CREDIT LIMIT
     (Section 1.1):                     An amount not to exceed (i) $2,000,000
                                        at any one time outstanding or (ii) 80%
                                        of the Net Amount of Borrower's
                                        accounts, which Silicon in its
                                        discretion deems eligible for borrowing.

                                        "Net Amount" of an account means the
                                        gross amount of the account, minus all
                                        applicable sales, use, excise and other
                                        similar taxes and minus all discounts,
                                        credits and allowances of any nature
                                        granted or claimed.

                                        Without limiting the fact that the
                                        determination of which accounts are
                                        eligible for borrowing is a matter of
                                        Silicon's discretion, the following will
                                        not be deemed eligible for


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SILICON VALLEY BANK                    AMENDMENT TO LOAN AND SECURITY AGREEMENT
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                                        borrowing: accounts outstanding for
                                        more than 90 days from the invoice date,
                                        accounts subject to any contingencies,
                                        accounts owing from any government
                                        agency (unless Borrower completes such
                                        assignment of claims documentation and
                                        other documentation that Silicon
                                        determines is necessary or desirable to
                                        perfect and protect the interest of
                                        Silicon therein), accounts owing from an
                                        account debtor outside the United States
                                        (unless pre-approved by Silicon in its
                                        discretion, or backed by a letter of
                                        credit satisfactory to Silicon, or FCIA
                                        insured satisfactory to Silicon),
                                        accounts owing from one account debtor
                                        to the extent they exceed 25% of the
                                        total eligible accounts outstanding,
                                        accounts owing from an affiliate of
                                        Borrower, and accounts owing from an
                                        account debtor to whom Borrower is or
                                        may be liable for goods purchased from
                                        such account debtor or otherwise. In
                                        addition, if more than 50% of the
                                        accounts owing from an account debtor
                                        are outstanding more than 90 days from
                                        the invoice date or are otherwise not
                                        eligible accounts, then all accounts
                                        owing from that account debtor will be
                                        deemed ineligible for borrowing.

     STANDBY LETTER OF CREDIT           In addition to the Loans available to
                                        the Borrower as set forth above, Silicon
                                        has issued a standby letter of credit in
                                        the amount of $300,000 that is cash
                                        collateralized on a separate basis
                                        pursuant to standard Silicon
                                        documentation and such standby letter of
                                        credit obligations are not considered a
                                        sublimit of the Credit Limit set forth
                                        above."

         2. REVISED FINANCIAL COVENANTS. That section of the Schedule to Loan
Agreement entitled "Credit Limit (Section 1.1)" is hereby amended in its
entirety to read as follows:

     "FINANCIAL COVENANTS
       (Section 4.1):                   Borrower shall comply with all of the
                                        following covenants. Compliance shall be
                                        determined as of the end of each month,
                                        except as otherwise specifically
                                        provided below:

     LIQUIDITY COVENANT                 Borrower shall maintain cash on hand,
                                        cash equivalents and marketable
                                        securities in an amount not less than
                                        $6,000,000, with the understanding that
                                        at least $2,000,000 thereof shall be on
                                        deposit with Silicon at all times.

     DEBT TO NET WORTH RATIO:           Borrower shall maintain a ratio of total
                                        liabilities to tangible net worth of not
                                        more than 1.00 to 1.

     PROFITABILITY:                     Borrower shall not incur a loss (after
                                        taxes) for the fiscal quarter ending
                                        December 31, 1999 in excess of
                                        $1,000,000; and Borrower shall not incur
                                        a loss (after taxes) for the fiscal
                                        quarter ending March 31, 2000 in excess
                                        of $1,000,000. Alternatively, Borrower
                                        shall also be deemed to comply with this
                                        covenant if Borrower does not incur a
                                        loss (after taxes) in excess of
                                        $2,000,000 for the two quarter
                                        cumulative period ending March 31, 2000.


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SILICON VALLEY BANK                    AMENDMENT TO LOAN AND SECURITY AGREEMENT
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     DEFINITIONS:                       "Current assets," and "current
                                        liabilities" shall have the meanings
                                        ascribed to them in accordance with
                                        generally accepted accounting
                                        principles.

                                        "Tangible net worth" means the excess of
                                        total assets over total liabilities,
                                        determined in accordance with generally
                                        accepted accounting principles,
                                        excluding however all assets which would
                                        be classified as intangible assets under
                                        generally accepted accounting
                                        principles, including without limitation
                                        goodwill, licenses, patents, trademarks,
                                        trade names, copyrights, and franchises.

                                        "Quick Assets" means cash on hand or on
                                        deposit in banks, readily marketable
                                        securities issued by the United States,
                                        readily marketable commercial paper
                                        rated "A-1" by Standard & Poor's
                                        Corporation (or a similar rating by a
                                        similar rating organization),
                                        certificates of deposit and banker's
                                        acceptances, and accounts receivable
                                        (net of allowance for doubtful
                                        accounts).

     SUBORDINATED DEBT:                 "Liabilities" for purposes of the
                                        foregoing covenants do not include
                                        indebtedness which is subordinated to
                                        the indebtedness to Silicon under a
                                        subordination agreement in form
                                        specified by Silicon or by language in
                                        the instrument evidencing the
                                        indebtedness which is acceptable to
                                        Silicon."

         3. REPORTING. Paragraph 2 of that section of the Schedule to Loan
Agreement entitled "Other Covenants (Section 4.1)" is hereby amended in its
entirety to read as follows:

         "2. MONTHLY BORROWING BASE CERTIFICATE AND LISTING. Within 20 days of
          the end of each month, Borrower shall provide Silicon with a Borrowing
          Base Certificate in such form as Silicon shall specify, and an aged
          listing of Borrower's accounts receivable."

         4. FEE. Borrower shall pay to Silicon a facility fee in the amount of
$1,000 concurrently, which shall be in addition to all interest and all other
amounts payable under the Loan Agreement, and which shall not be refundable.

         5. REPRESENTATIONS TRUE. Borrower represents and warrants to Silicon
that all representations and warranties set forth in the Loan Agreement, as
amended hereby, are true and correct.

         6. GENERAL PROVISIONS. This Amendment, the Loan Agreement, any prior
written amendments to the Loan Agreement signed by Silicon and the Borrower, and
the other written documents and agreements between Silicon and the Borrower set
forth in full all of the representations and agreements of the parties with
respect to the subject matter hereof and supersede all prior discussions,
representations, agreements and understandings between the parties with respect
to the subject hereof. Except as herein expressly amended, all of the terms and
provisions of the Loan Agreement, as so amended, and all other documents and
agreements between Silicon and the Borrower shall continue in full force and
effect and the same are hereby ratified and confirmed.


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SILICON VALLEY BANK                    AMENDMENT TO LOAN AND SECURITY AGREEMENT
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   SYNC RESEARCH, INC.                               SILICON VALLEY BANK


   By    /s/ William K. Guerry                     By     /s/ Marla Johnson
         PRESIDENT OR VICE PRESIDENT
         ----------------------------                     --------------------
                                                   Title   VICE PRESIDENT
                                                          --------------------


   By    /s/ William K. Guerry
         SECRETARY OR ASS'T SECRETARY
         ----------------------------


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SILICON VALLEY BANK

CERTIFIED RESOLUTION

BORROWER:                  SYNC RESEARCH, INC., A CORPORATION
                           ORGANIZED UNDER THE LAWS OF THE
                           STATE OF DELAWARE

ADDRESS:                   12 MORGAN
                           IRVINE, CALIFORNIA  92618

DATE:                      OCTOBER 31, 1999

         I, the undersigned, Secretary or Assistant Secretary of the above-named
borrower, a corporation organized under the laws of the state set forth above,
do hereby certify that the following is a full, true and correct copy of
resolutions duly and regularly adopted by the Board of Directors of said
corporation as required by law, and by the by-laws of said corporation, and that
said resolutions are still in full force and effect and have not been in any way
modified, repealed, rescinded, amended or revoked.

     RESOLVED, that this corporation borrow from Silicon Valley Bank
     ("Silicon"), from time to time, such sum or sums of money as, in the
     judgment of the officer or officers hereinafter authorized hereby, this
     corporation may require.

     RESOLVED FURTHER, that any officer of this corporation be, and he or she is
     hereby authorized, directed and empowered, in the name of this corporation,
     to execute and deliver to Silicon, and Silicon is requested to accept, the
     loan agreements, security agreements, notes, financing statements, and
     other documents and instruments providing for such loans and evidencing
     and/or securing such loans, with interest thereon, and said authorized
     officers are authorized from time to time to execute renewals, extensions
     and/or amendments of said loan agreements, security agreements, and other
     documents and instruments.

     RESOLVED FURTHER, that said authorized officers be and they are hereby
     authorized, directed and empowered, as security for any and all
     indebtedness of this corporation to Silicon, whether arising pursuant to
     this resolution or otherwise, to grant, transfer, pledge, mortgage, assign,
     or otherwise hypothecate to Silicon, or deed in trust for its benefit, any
     property of any and every kind, belonging to this corporation, including,
     but not limited to, any and all real property, accounts, inventory,
     equipment, general intangibles, instruments, documents, chattel paper,
     notes, money, deposit accounts, furniture, fixtures, goods, and other
     property of every kind, and to execute and deliver to Silicon any and all
     grants, transfers, trust receipts, loan or credit agreements, pledge
     agreements, mortgages, deeds of trust, financing statements, security
     agreements and other hypothecation agreements, which said instruments and
     the note or notes and other instruments referred to in the preceding
     paragraph may contain such provisions, covenants, recitals and agreements
     as Silicon may require and said authorized officers may approve, and the
     execution thereof by said authorized officers shall be conclusive evidence
     of such approval.

     RESOLVED FURTHER, that Silicon may conclusively rely upon a certified copy
     of these resolutions and a certificate of the Secretary or Ass't Secretary
     of this corporation as to the officers of this corporation and their
     offices and signatures, and continue to conclusively rely on such certified
     copy of these resolutions and said certificate for all past, present and
     future transactions until written notice of any change hereto or thereto is
     given to Silicon by this corporation by certified mail, return receipt
     requested.

   The undersigned further hereby certifies that the following persons are the
duly elected and acting officers of the corporation named above as borrower and
that the following are their actual signatures:

<TABLE>
<CAPTION>

   NAMES                                    OFFICE(S)                                   ACTUAL SIGNATURES
   -----                                    ---------                                   -----------------
   <S>                                      <C>                                         <C>
   William K. Guerry                        President & Ceo                             x /s/ William K. Guerry
   ------------------------------           -------------------------------              ---------------------------

   ------------------------------           -------------------------------             x---------------------------
</TABLE>

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SILICON VALLEY BANK                                 LOAN AND SECURITY AGREEMENT
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<TABLE>



   <S>                                      <C>                                         <C>

   ------------------------------           -------------------------------             x---------------------------

   ------------------------------           -------------------------------             x---------------------------
</TABLE>


   IN WITNESS WHEREOF, I have hereunto set my hand as such Secretary or
Assistant Secretary on the date set forth above.

                                                /s/ William K. Guerry
                                                --------------------------------
                                                Secretary or Assistant Secretary


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