Document:

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                                                                    EXHIBIT 10.4

                                                                       EXHIBIT A
                                                   TO PLACEMENT AGENCY AGREEMENT

       VOID AFTER 5:00 P.M., NEW YORK CITY
       TIME, ON SEPTEMBER 8, 2005
       (UNLESS EXTENDED PURSUANT TO SECTION 2 HEREOF)

       THIS WARRANT AND THE SHARES ISSUABLE UPON EXERCISE OF THIS WARRANT HAVE
       NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
       "SECURITIES ACT"), OR THE SECURITIES LAWS OF ANY STATE OF THE UNITED
       STATES OR ANY OTHER JURISDICTION. THE SECURITIES REPRESENTED HEREBY MAY
       NOT BE OFFERED OR SOLD IN THE ABSENCE OF AN EFFECTIVE REGISTRATION
       STATEMENT FOR THE SECURITIES UNDER APPLICABLE SECURITIES LAWS UNLESS
       OFFERED, SOLD OR TRANSFERRED PURSUANT TO AN AVAILABLE EXEMPTION FROM THE
       REGISTRATION REQUIREMENTS OF THOSE LAWS.

                                          Right to Purchase _________ Shares of
                                          Common Stock, par value $.01 per share

Date: September 8, 2000

                       FASTCOMM COMMUNICATIONS CORPORATION
                             STOCK PURCHASE WARRANT

       THIS CERTIFIES THAT, for value received, _________________________, or
its registered assigns, is entitled to purchase from FASTCOMM COMMUNICATIONS
CORPORATION, a corporation organized under the laws of the Commonwealth of
Virginia (the "COMPANY"), at any time or from time to time during the period
specified in Section 2 hereof, _______________________ (__________) [1/4 share
for each share purchasable at time of closing] fully paid and nonassessable
shares of the Company's common stock, par value $.001 per share (the "COMMON
STOCK"), at an exercise price per share (the "EXERCISE PRICE") equal to $___
_____ [125% of market price (5 day moving average of closing bid price prior to
Closing)] The number of shares of Common Stock purchasable hereunder (the
"WARRANT SHARES") and the Exercise Price are subject to adjustment as provided
in Section 4 hereof. The term "WARRANTS" means this Warrant and the other
warrants of the Company issued pursuant to, and identified as Warrants in, that
certain Securities Purchase Agreement, dated as of September ___, 2000, by and
among the Company and the other signatories thereto (the "SECURITIES PURCHASE
AGREEMENT").

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       This Warrant is subject to the following terms, provisions and
conditions:

       1.     Manner of Exercise; Issuance of Certificates; Payment for Shares.
Subject to the provisions hereof, including, without limitation, the limitations
contained in Section 7 hereof, this Warrant may be exercised by the holder
hereof, in whole or in part, by the surrender of this Warrant, together with a
completed exercise agreement in the form attached hereto (the "EXERCISE
AGREEMENT"), to the Company during normal business hours on any business day at
the Company's principal executive offices (or such other office or agency of the
Company as it may designate by notice to the holder hereof), and upon payment to
the Company in cash, by certified or official bank check or by wire transfer for
the account of the Company, of the Exercise Price for the Warrant Shares
specified in the Exercise Agreement. The Warrant Shares so purchased shall be
deemed to be issued to the holder hereof or such holder's designee, as the
record owner of such shares, as of the close of business on the date on which
this Warrant shall have been surrendered, the completed Exercise Agreement shall
have been delivered, and payment shall have been made for such shares as set
forth above or, if such date is not a business date, on the next succeeding
business date. Certificates for the Warrant Shares so purchased, representing
the aggregate number of shares specified in the Exercise Agreement, shall be
delivered to the holder hereof within a reasonable time, not exceeding three (3)
business days, after this Warrant shall have been so exercised (the "DELIVERY
PERIOD"). The certificates so delivered shall be in such denominations as may be
requested by the holder hereof and shall be registered in the name of such
holder or such other name as shall be designated by such holder. If this Warrant
shall have been exercised only in part, then, unless this Warrant has expired,
the Company shall, at its expense, at the time of delivery of such certificates,
deliver to the holder a new Warrant representing the number of shares with
respect to which this Warrant shall not then have been exercised.

       Unless the Corporation has notified Holder in writing prior to the
delivery by Holder of an Exercise Agreement that the Corporation is unable to
honor exercises, if (i) the Corporation fails for any reason to deliver during
the Delivery Period shares of Common Stock to Holder upon an exercise of this
Warrant and (ii) thereafter, Holder purchases (in an open market transaction or
otherwise) shares of Common Stock to make delivery in satisfaction of a sale by
Holder of the unlegended shares of Common Stock (the "SOLD SHARES") which Holder
anticipated receiving upon such exercise (a "BUY-IN"), the Corporation shall pay
Holder (in addition to any other remedies available to Holder) the amount by
which (x) Holder's total purchase price (including brokerage commissions, if
any) for the unlegended shares of Common Stock so purchased exceeds (y) the net
proceeds received by Holder from the sale of the Sold Shares. For example, if
Holder purchases unlegended shares of Common Stock having a total purchase price
of $11,000 to cover a Buy-In with respect to shares of Common Stock it sold for
$10,000, the Corporation will be required to pay Holder $1,000. Holder shall
provide the Corporation written notification indicating any amounts payable to
Holder pursuant to this Section, together with evidence supporting such
calculation. The Corporation shall make any payments required pursuant to this
Section within five (5) business days after its receipt of written notice from
the Holder of such amount.

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       Nothing herein shall limit the holder's right to pursue actual damages
for the Company's failure to maintain a sufficient number of authorized shares
of Common Stock as required pursuant to the terms of Section 3(b) hereof or to
otherwise issue shares of Common Stock upon exercise of this Warrant in
accordance with the terms hereof, and the holder shall have the right to pursue
all remedies available at law or in equity (including a decree of specific
performance and/or injunctive relief.

       2.     Period of Exercise.

              (a)    This Warrant is immediately exercisable, at any time or
from time to time on or after the date of initial issuance of this Warrant (the
"ISSUE DATE") and before 5:00 p.m., New York City time, on the fifth (5th)
anniversary of the Issue Date (the "EXERCISE PERIOD"). The Exercise Period shall
automatically be extended by one (1) day for each day on which the Company does
not have a number of shares of Common Stock reserved for issuance upon exercise
hereof at least equal to the number of shares of Common Stock issuable upon
exercise hereof.

       3.     Certain Agreements of the Company. The Company hereby covenants
and agrees as follows:

              (a)    Shares to be Fully Paid. All Warrant Shares will, upon
issuance in accordance with the terms of this Warrant, be validly issued, fully
paid, and nonassessable and free from all taxes, liens, claims and encumbrances.

              (b)    Reservation of Shares. During the Exercise Period, the
Company shall at all times have authorized, and reserved for the purpose of
issuance upon exercise of this Warrant, a sufficient number of shares of Common
Stock to provide for the exercise in full of this Warrant (without giving effect
to the limitations on exercise set forth in Section 7(g) hereof).

              (c)    Listing. The Company shall promptly secure the listing of
the shares of Common Stock issuable upon exercise of this Warrant upon each
national securities exchange or automated quotation system, if any, upon which
shares of Common Stock are then listed or become listed (subject to official
notice of issuance upon exercise of this Warrant) and shall maintain, so long as
any other shares of Common Stock shall be so listed, such listing of all shares
of Common Stock from time to time issuable upon the exercise of this Warrant;
and the Company shall so list on each national securities exchange or automated
quotation system, as the case may be, and shall maintain such listing of, any
other shares of capital stock of the Company issuable upon the exercise of this
Warrant if and so long as any shares of the same class shall be listed on such
national securities exchange or automated quotation system.

              (d)    Certain Actions Prohibited. The Company will not, by
amendment of its charter or through any reorganization, transfer of assets,
consolidation, merger, dissolution, issue or sale of securities, or any other
voluntary action, avoid or seek to avoid the observance or performance of any of
the terms to be observed or performed by it hereunder, but will at all times

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in good faith assist in the carrying out of all the provisions of this Warrant
and in the taking of all such action as may reasonably be requested by the
holder of this Warrant in order to protect the economic benefit inuring to the
holder hereof and the exercise privilege of the holder of this Warrant against
dilution or other impairment, consistent with the tenor and purpose of this
Warrant. Without limiting the generality of the foregoing, the Company (i) will
not increase the par value of any shares of Common Stock receivable upon the
exercise of this Warrant above the Exercise Price then in effect, and (ii) will
take all such actions as may be necessary or appropriate in order that the
Company may validly and legally issue fully paid and nonassessable shares of
Common Stock upon the exercise of this Warrant.

              (e)    Successors and Assigns. This Warrant will be binding upon
any entity succeeding to the Company by merger, consolidation, or acquisition of
all or substantially all of the Company's assets.

              (f)    Blue Sky Laws. The Company shall, on or before the date of
issuance of any Warrant Shares, take such actions as the Company shall
reasonably determine are necessary to qualify the Warrant Shares for, or obtain
exemption for the Warrant Shares for, sale to the holder of this Warrant upon
the exercise hereof under applicable securities or "blue sky" laws of the states
of the United States, and shall provide evidence of any such action so taken to
the holder of this Warrant prior to such date; provided, however, that the
Company shall not be required to qualify as a foreign corporation or file a
general consent to service of process in any such jurisdiction.

       4.     Antidilution Provisions. During the Exercise Period, the Exercise
Price and the number of Warrant Shares issuable hereunder and for which this
Warrant is then exercisable pursuant to Section 2 hereof shall be subject to
adjustment from time to time as provided in this Section 4.

       In the event that any adjustment of the Exercise Price as required herein
results in a fraction of a cent, such Exercise Price shall be rounded up or down
to the nearest cent.

              (a)    Adjustment of Exercise Price. Except as otherwise provided
in Sections 4(c) and 4(e) hereof, if and whenever during the Exercise Period the
Company issues or sells, or in accordance with Section 4(b) hereof is deemed to
have issued or sold, any shares of Common Stock for no consideration or for a
consideration per share less than the Market Price (as hereinafter defined) on
the date of issuance (a "DILUTIVE ISSUANCE"), then effective immediately upon
the Dilutive Issuance, the Exercise Price will be adjusted in accordance with
the following formula:

              E' = E x       O + P/M
                       ---------------------
                              CSDO

              where:

              E'   =   the adjusted Exercise Price;

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              E    =   the then current Exercise Price;
              M    =   the then current Market Price (as defined in Section
                       4(1)(ii));
              O    =   the number of shares of Common Stock outstanding
                       immediately prior to the Dilutive Issuance;
              P    =   the aggregate consideration, calculated as set forth in
                       Section 4(b) hereof, received by the Company upon such
                       Dilutive Issuance; and
              CSDO =   the total number of shares of Common Stock Deemed
                       Outstanding (as defined in Section 4(l)(i)) immediately
                       after the Dilutive Issuance.

              (b)    Effect on Exercise Price of Certain Events. For purposes of
determining the adjusted Exercise Price under Section 4(a) hereof, the following
will be applicable:

                     (i)    Issuance of Rights or Options. If the Company in any
manner issues or grants any warrants, rights or options, whether or not
immediately exercisable, to subscribe for or to purchase Common Stock or other
securities exercisable, convertible into or exchangeable for Common Stock
("CONVERTIBLE SECURITIES") (such warrants, rights and options to purchase Common
Stock or Convertible Securities are hereinafter referred to as "OPTIONS") and
the price per share for which Common Stock is issuable upon the exercise of such
Options is less than the Market Price in effect on the date of issuance of such
Options ("BELOW MARKET OPTIONS"), then the maximum total number of shares of
Common Stock issuable upon the exercise of all such Below Market Options
(assuming full exercise, conversion or exchange of Convertible Securities, if
applicable) will, as of the date of the issuance or grant of such Below Market
Options, be deemed to be outstanding and to have been issued and sold by the
Company for such price per share. For purposes of the preceding sentence, the
"price per share for which Common Stock is issuable upon the exercise of such
Below Market Options" is determined by dividing (i) the total amount, if any,
received or receivable by the Company as consideration for the issuance or
granting of all such Below Market Options, plus the minimum aggregate amount of
additional consideration, if any, payable to the Company upon the exercise of
all such Below Market Options, plus, in the case of Convertible Securities
issuable upon the exercise of such Below Market Options, the minimum aggregate
amount of additional consideration payable upon the exercise, conversion or
exchange thereof at the time such Convertible Securities first become
exercisable, convertible or exchangeable, by (ii) the maximum total number of
shares of Common Stock issuable upon the exercise of all such Below Market
Options (assuming full conversion of Convertible Securities, if applicable). No
further adjustment to the Exercise Price will be made upon the actual issuance
of such Common Stock upon the exercise of such Below Market Options or upon the
exercise, conversion or exchange of Convertible Securities issuable upon
exercise of such Below Market Options.

                     (ii)   Issuance of Convertible Securities.

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                            (A)    If the Company in any manner issues or sells
any Convertible Securities, whether or not immediately convertible (other than
where the same are issuable upon the exercise of Options) and the price per
share for which Common Stock is issuable upon such exercise, conversion or
exchange (as determined pursuant to Section 4(b)(ii)(B) if applicable) is less
than the Market Price in effect on the date of issuance of such Convertible
Securities, then the maximum total number of shares of Common Stock issuable
upon the exercise, conversion or exchange of all such Convertible Securities
will, as of the date of the issuance of such Convertible Securities, be deemed
to be outstanding and to have been issued and sold by the Company for such price
per share. For the purposes of the preceding sentence, the "price per share for
which Common Stock is issuable upon such exercise, conversion or exchange" is
determined by dividing (i) the total amount, if any, received or receivable by
the Company as consideration for the issuance or sale of all such Convertible
Securities, plus the minimum aggregate amount of additional consideration, if
any, payable to the Company upon the exercise, conversion or exchange thereof at
the time such Convertible Securities first become exercisable, convertible or
exchangeable, by (ii) the maximum total number of shares of Common Stock
issuable upon the exercise, conversion or exchange of all such Convertible
Securities. No further adjustment to the Exercise Price will be made upon the
actual issuance of such Common Stock upon exercise, conversion or exchange of
such Convertible Securities.

                            (B)    If the Company in any manner issues or sells
any Convertible Securities with a fluctuating conversion or exercise price or
exchange ratio (a "VARIABLE RATE CONVERTIBLE SECURITY"), then the "price per
share for which Common Stock is issuable upon such exercise, conversion or
exchange" for purposes of the calculation contemplated by Section 4(b)(ii)(A)
shall be deemed to be the lowest price per share which would be applicable
(assuming all holding period and other conditions to any discounts contained in
such Convertible Security have been satisfied) if the Market Price on the date
of issuance of such Convertible Security was 75% of the Market Price on such
date (the "ASSUMED VARIABLE MARKET PRICE"). Further, if the Market Price at any
time or times thereafter is less than or equal to the Assumed Variable Market
Price last used for making any adjustment under this Section 4 with respect to
any Variable Rate Convertible Security, the Exercise Price in effect at such
time shall be readjusted to equal the Exercise Price which would have resulted
if the Assumed Variable Market Price at the time of issuance of the Variable
Rate Convertible Security had been 75% of the Market Price existing at the time
of the adjustment required by this sentence.

                     (iii)  Change in Option Price or Conversion Rate. If there
is a change at any time in (i) the amount of additional consideration payable to
the Company upon the exercise of any Options; (ii) the amount of additional
consideration, if any, payable to the Company upon the exercise, conversion or
exchange of any Convertible Securities; or (iii) the rate at which any
Convertible Securities are convertible into or exchangeable for Common Stock (in
each such case, other than under or by reason of provisions designed to protect
against dilution), the Exercise Price in effect at the time of such change will
be readjusted to the Exercise Price which would have been in effect at such time
had such Options or Convertible Securities still outstanding provided for such

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changed additional consideration or changed conversion rate, as the case may be,
at the time initially granted, issued or sold.

                     (iv)   Treatment of Expired Options and Unexercised
Convertible Securities. If, in any case, the total number of shares of Common
Stock issuable upon exercise of any Option or upon exercise, conversion or
exchange of any Convertible Securities is not, in fact, issued and the rights to
exercise such Option or to exercise, convert or exchange such Convertible
Securities shall have expired or terminated, the Exercise Price then in effect
will be readjusted to the Exercise Price which would have been in effect at the
time of such expiration or termination had such Option or Convertible
Securities, to the extent outstanding immediately prior to such expiration or
termination (other than in respect of the actual number of shares of Common
Stock issued upon exercise or conversion thereof), never been issued.

                     (v)    Calculation of Consideration Received. If any Common
Stock, Options or Convertible Securities are issued, granted or sold for cash,
the consideration received therefor for purposes of this Warrant will be the
amount received by the Company therefor, before deduction of reasonable
commissions, underwriting discounts or allowances or other reasonable expenses
paid or incurred by the Company in connection with such issuance, grant or sale.
In case any Common Stock, Options or Convertible Securities are issued or sold
for a consideration part or all of which shall be other than cash, the amount of
the consideration other than cash received by the Company will be the fair
market value of such consideration, except where such consideration consists of
securities, in which case the amount of consideration received by the Company
will be the Market Price thereof as of the date of receipt. In case any Common
Stock, Options or Convertible Securities are issued in connection with any
merger or consolidation in which the Company is the surviving corporation, the
amount of consideration therefor will be deemed to be the fair market value of
such portion of the net assets and business of the non-surviving corporation as
is attributable to such Common Stock, Options or Convertible Securities, as the
case may be. The fair market value of any consideration other than cash or
securities will be determined in good faith by an investment banker or other
appropriate expert of national reputation selected by the Company and reasonably
acceptable to the holder hereof, with the costs of such appraisal to be borne by
the Company.

                     (vi)   Exceptions to Adjustment of Exercise Price. No
adjustment to the Exercise Price will be made (i) upon the exercise of any
warrants, options or convertible securities issued and outstanding on the Issue
Date and set forth on Schedule 3(c) of the Securities Purchase Agreement in
accordance with the terms of such securities as of such date; (ii) upon the
grant or exercise of any stock or options which may hereafter be granted or
exercised under any employee benefit plan of the Company now existing or to be
implemented in the future, so long as the issuance of such stock or options is
approved by a majority of the non-employee members of the Board of Directors of
the Company or a majority of the members of a committee of non-employee
directors established for such purpose; (iii) upon the issuance of any Prepaid
Warrants (as such term is defined in the Securities Purchase Agreement) or
Incentive Warrants issued or issuable in accordance with

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the terms of the Securities Purchase Agreement; or (iv) upon exercise of the
Prepaid Warrants and the Incentive Warrants.

              (c)    Subdivision or Combination of Common Stock. If the Company,
at any time during the Exercise Period, subdivides (by any stock split, stock
dividend, recapitalization, reorganization, reclassification or otherwise) its
shares of Common Stock into a greater number of shares, then, after the date of
record for effecting such subdivision, the Exercise Price in effect immediately
prior to such subdivision will be proportionately reduced. If the Company, at
any time during the Exercise Period, combines (by reverse stock split,
recapitalization, reorganization, reclassification or otherwise) its shares of
Common Stock into a smaller number of shares, then, after the date of record for
effecting such combination, the Exercise Price in effect immediately prior to
such combination will be proportionately increased.

              (d)    Adjustment in Number of Shares. Upon each adjustment of the
Exercise Price pursuant to the provisions of this Section 4, the number of
shares of Common Stock issuable upon exercise of this Warrant and for which this
Warrant is or may become exercisable shall be adjusted by multiplying a number
equal to the Exercise Price in effect immediately prior to such adjustment by
the number of shares of Common Stock issuable or for which this Warrant is or
may become exercisable (as applicable) upon exercise of this Warrant immediately
prior to such adjustment and dividing the product so obtained by the adjusted
Exercise Price.

              (e)    Consolidation, Merger or Sale. In case of any consolidation
of the Company with, or merger of the Company into any other corporation, or in
case of any sale or conveyance of all or substantially all of the assets of the
Company other than in connection with a plan of complete liquidation of the
Company at any time during the Exercise Period, then as a condition of such
consolidation, merger or sale or conveyance, adequate provision will be made
whereby the holder of this Warrant will have the right to acquire and receive
upon exercise of this Warrant in lieu of the shares of Common Stock immediately
theretofore acquirable upon the exercise of this Warrant, such shares of stock,
securities, cash or assets as may be issued or payable with respect to or in
exchange for the number of shares of Common Stock immediately theretofore
acquirable and receivable upon exercise of this Warrant had such consolidation,
merger or sale or conveyance not taken place. In any such case, the Company will
make appropriate provision to insure that the provisions of this Section 4
hereof will thereafter be applicable as nearly as may be in relation to any
shares of stock or securities thereafter deliverable upon the exercise of this
Warrant. The Company will not effect any consolidation, merger or sale or
conveyance unless prior to the consummation thereof, the successor corporation
(if other than the Company) assumes by written instrument the obligations under
this Warrant and the obligations to deliver to the holder of this Warrant such
shares of stock, securities or assets as, in accordance with the foregoing
provisions, the holder may be entitled to acquire. Notwithstanding the
foregoing, in the event of any such sale or conveyance, the holder of this
Warrant shall, at its option, have the right to receive, and, in the event of
any such merger, consolidation, sale or conveyance which involves the receipt of
cash consideration by the equity holders of the Company's capital stock or in
which the surviving or continuing entity is not a publicly traded corporation
whose common stock is listed for trading on the New York Stock

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Exchange, the American Stock Exchange, the Nasdaq National Market or the Nasdaq
SmallCap Market, the holder of this Warrant shall be entitled to receive, in
connection with such transaction, cash consideration at a per share price equal
to the other stockholders' per share price.

              (f)    Distribution of Assets. In case the Company shall declare
or make any distribution of its assets (or rights to acquire its assets) to
holders of Common Stock as a partial liquidating dividend, stock repurchase by
way of return of capital or otherwise (including any dividend or distribution to
the Company's shareholders of cash or shares (or rights to acquire shares) of
capital stock of a subsidiary) (a "DISTRIBUTION"), at any time during the
Exercise Period, then the holder of this Warrant shall be entitled upon exercise
of this Warrant for the purchase of any or all of the shares of Common Stock
subject hereto, to receive the amount of such assets (or rights) which would
have been payable to the holder had such holder been the holder of such shares
of Common Stock on the record date for the determination of shareholders
entitled to such Distribution.

              (g)    Notice of Adjustment. Upon the occurrence of any event
which requires any adjustment of the Exercise Price, then, and in each such
case, the Company shall give 10 day notice thereof to the holder of this
Warrant, which notice shall state the Exercise Price resulting from such
adjustment and the increase or decrease in the number of Warrant Shares
purchasable at such price upon exercise, setting forth in reasonable detail the
method of calculation and the facts upon which such calculation is based. Such
calculation shall be certified by the chief financial officer of the Company.

              (h)    Minimum Adjustment of Exercise Price. No adjustment of the
Exercise Price shall be made in an amount of less than 1% of the Exercise Price
in effect at the time such adjustment is otherwise required to be made, but any
such lesser adjustment shall be carried forward and shall be made at the time
and together with the next subsequent adjustment which, together with any
adjustments so carried forward, shall amount to not less than 1% of such
Exercise Price.

              (i)    No Fractional Shares. No fractional shares of Common Stock
are to be issued upon the exercise of this Warrant, but the Company shall pay a
cash adjustment in respect of any fractional share which would otherwise be
issuable in an amount equal to the same fraction of the Market Price of a share
of Common Stock on the date of such exercise.

              (j)    Other Notices. In case at any time:

                     (i)    the Company shall declare any dividend upon the
Common Stock payable in shares of stock of any class or make any other
distribution (other than dividends or distributions payable in cash out of
retained earnings consistent with the Company's past practices with respect to
declaring dividends and making distributions) to the holders of the Common
Stock;

                     (ii)   the Company shall offer for subscription pro rata to
the holders of the Common Stock any additional shares of stock of any class or
other rights;

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                     (iii)  there shall be any capital reorganization of the
Company, or reclassification of the Common Stock, or consolidation or merger of
the Company with or into, or sale of all or substantially all of its assets to,
another corporation or entity; or

                     (iv)   there shall be a voluntary or involuntary
dissolution, liquidation or winding-up of the Company;
then, in each such case, the Company shall give to the holder of this Warrant
(a) notice of the date on which the books of the Company shall close or a record
shall be taken for determining the holders of Common Stock entitled to receive
any such dividend, distribution, or subscription rights or for determining the
holders of Common Stock entitled to vote in respect of any such reorganization,
reclassification, consolidation, merger, sale, dissolution, liquidation or
winding-up and (b) in the case of any such reorganization, reclassification,
consolidation, merger, sale, dissolution, liquidation or winding-up, notice of
the date (or, if not then known, a reasonable estimate thereof by the Company)
when the same shall take place. Such notice shall also specify the date on which
the holders of Common Stock shall be entitled to receive such dividend,
distribution, or subscription rights or to exchange their Common Stock for stock
or other securities or property deliverable upon such reorganization,
reclassification, consolidation, merger, sale, dissolution, liquidation, or
winding-up, as the case may be. Such notice shall be given at least twenty (20)
days prior to the record date or the date on which the Company's books are
closed in respect thereto. Failure to give any such notice or any defect therein
shall not affect the validity of the proceedings referred to in clauses (i),
(ii), (iii) and (iv) above.

              (k)    [Intentionally omitted].

              (l)    Certain Definitions.

                     (i)    "COMMON STOCK DEEMED OUTSTANDING" shall mean the
number of shares of Common Stock actually outstanding (not including shares of
Common Stock held in the treasury of the Company), plus (x) in the case of any
adjustment required by Section 4(a) resulting from the issuance of any Options,
the maximum total number of shares of Common Stock issuable upon the exercise of
the Options for which the adjustment is required (including any Common Stock
issuable upon the conversion of Convertible Securities issuable upon the
exercise of such Options), and (y) in the case of any adjustment required by
Section 4(a) resulting from the issuance of any Convertible Securities, the
maximum total number of shares of Common Stock issuable upon the exercise,
conversion or exchange of the Convertible Securities for which the adjustment is
required, as of the date of issuance of such Convertible Securities, if any.

                     (ii)   "MARKET PRICE," as of any date, (i) means the
average of the closing bid prices for the shares of Common Stock as reported on
the Nasdaq Over-the-Counter Bulletin Board ("BULLETIN BOARD") Bloomberg
Financial Markets ("BLOOMBERG") for the five (5) consecutive trading days
immediately preceding such date, or (ii) if the Bulletin Board is not the
principal trading market for the shares of Common Stock, the average of the last
sale prices reported by Bloomberg on the principal trading market for the Common
Stock during the same period, or,

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if there is no sale price for such period, the last bid price reported by
Bloomberg for such period, or (iii) if the foregoing do not apply, the last sale
price of such security in the over-the-counter market on the pink sheets or
bulletin board for such security as reported by Bloomberg, or if no sale price
is so reported for such security, the last bid price of such security as
reported by Bloomberg, or (iv) if market value cannot be calculated as of such
date on any of the foregoing bases, the Market Price shall be the average fair
market value as reasonably determined by an investment banking firm selected by
the Company and reasonably acceptable to a majority in interest of the holders
of Incentive Warrants, with the costs of the appraisal to be borne by the
Company. The manner of determining the Market Price of the Common Stock set
forth in the foregoing definition shall apply with respect to any other security
in respect of which a determination as to market value must be made hereunder.

                     (iii)  "COMMON STOCK," for purposes of this Section 4,
includes the Common Stock and any additional class of stock of the Company
having no preference as to dividends or distributions on liquidation, provided
that the shares purchasable pursuant to this Warrant shall include only Common
Stock in respect of which this Warrant is exercisable, or shares resulting from
any subdivision or combination of such Common Stock, or in the case of any
reorganization, reclassification, consolidation, merger, or sale of the
character referred to in Section 4(e) hereof, the stock or other securities or
property provided for in such Section.

       5.     Issue Tax. The issuance of certificates for Warrant Shares upon
the exercise of this Warrant shall be made without charge to the holder of this
Warrant or such shares for any issuance tax or other costs in respect thereof,
provided that the Company shall not be required to pay any tax which may be
payable in respect of any transfer involved in the issuance and delivery of any
certificate in a name other than the holder of this Warrant.

       6.     No Rights or Liabilities as a Shareholder. This Warrant shall not
entitle the holder hereof to any voting rights or other rights as a shareholder
of the Company. No provision of this Warrant, in the absence of affirmative
action by the holder hereof to purchase Warrant Shares, and no mere enumeration
herein of the rights or privileges of the holder hereof, shall give rise to any
liability of such holder for the Exercise Price or as a shareholder of the
Company, whether such liability is asserted by the Company or by creditors of
the Company.

                                      -11-
<PAGE>   12

       7.     Transfer, Exchange, Redemption and Replacement of Warrant.

              (a)    Restriction on Transfer. This Warrant and the rights
granted to the holder hereof are transferable, in whole or in part, upon
surrender of this Warrant, together with a properly executed assignment in the
form attached hereto, at the office or agency of the Company referred to in
Section 7(e) below, provided, however, that any transfer or assignment shall be
subject to the conditions set forth in Sections 7(f) and (g) hereof and to the
provisions of Sections 2(f) and 2(g) of the Securities Purchase Agreement. Until
due presentment for registration of transfer on the books of the Company, the
Company may treat the registered holder hereof as the owner and holder hereof
for all purposes, and the Company shall not be affected by any notice to the
contrary. Notwithstanding anything to the contrary contained herein, the
registration rights described in Section 8 hereof are assignable only in
accordance with the provisions of that certain Registration Rights Agreement,
dated as of September __, 2000, by and among the Company and the other
signatories thereto (the "REGISTRATION RIGHTS AGREEMENT").

              (b)    Warrant Exchangeable for Different Denominations. This
Warrant is exchangeable, upon the surrender hereof by the holder hereof at the
office or agency of the Company referred to in Section 7(e) below, for new
Warrants of like tenor of different denominations representing in the aggregate
the right to purchase the number of shares of Common Stock which may be
purchased hereunder, each of such new Warrants to represent the right to
purchase such number of shares as shall be designated by the holder hereof at
the time of such surrender.

              (c)    Replacement of Warrant. Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction, or mutilation of
this Warrant and, in the case of any such loss, theft, or destruction, upon
delivery of an indemnity agreement reasonably satisfactory in form and amount to
the Company, or, in the case of any such mutilation, upon surrender and
cancellation of this Warrant, the Company, at its expense, will execute and
deliver, in lieu thereof, a new Warrant of like tenor.

              (d)    Cancellation; Payment of Expenses. Upon the surrender of
this Warrant in connection with any transfer, exchange, or replacement as
provided in this Section 7, this Warrant shall be promptly canceled by the
Company. The Company shall pay all taxes (other than securities transfer taxes)
and all other expenses (other than legal expenses, if any, incurred by the
Holder or transferees) and charges payable in connection with the preparation,
execution, and delivery of Warrants pursuant to this Section 7. The Company
shall indemnify and reimburse the holder of this Warrant for all costs and
expenses (including legal fees) incurred by such holder in connection with the
successful enforcement of its rights hereunder.

              (e)    Warrant Register. The Company shall maintain, at its
principal executive offices (or such other office or agency of the Company as it
may designate by notice to the holder hereof), a register for this Warrant, in
which the Company shall record the name and address of the person in whose name
this Warrant has been issued, as well as the name and address of each transferee
and each prior owner of this Warrant.

                                      -12-
<PAGE>   13

              (f)    Exercise or Transfer Without Registration. If, at the time
of the surrender of this Warrant in connection with any exercise, transfer, or
exchange of this Warrant, this Warrant (or, in the case of any exercise, the
Warrant Shares issuable hereunder), shall not be registered under the Securities
Act and under applicable state securities or blue sky laws, the Company may
require, as a condition of allowing such exercise, transfer, or exchange, (i)
that the holder or transferee of this Warrant, as the case may be, furnish to
the Company a written opinion of counsel (which opinion shall be in form,
substance and scope customary for opinions of counsel in comparable
transactions) to the effect that such exercise, transfer, or exchange may be
made without registration under the Securities Act and under applicable state
securities or blue sky laws (the cost of which shall be borne by the Company if
the Company's counsel renders such an opinion and up to $250 of such cost shall
be borne by the Company if the holder's counsel is requested to render such
opinion), (ii) that the holder or transferee execute and deliver to the Company
an investment letter in form and substance acceptable to the Company and (iii)
that the transferee be an "ACCREDITED INVESTOR" as defined in Rule 501(a)
promulgated under the Securities Act; provided that no such opinion, letter, or
status as an "accredited investor" shall be required in connection with a
transfer pursuant to Rule 144 under the Securities Act.

              (g)    Additional Restrictions on Exercise or Transfer. Unless the
holder of this Warrant delivers a waiver in accordance with the last sentence of
this Section 7(g), this Warrant shall not be exercisable by a holder hereof to
the extent (but only to the extent) that the sum of (a) the number of Common
Stock beneficially owned by such holder and its affiliates, and (b) the number
of Common Stock issuable upon exercise of the Warrant (or portion thereof) with
respect to which the determination described herein is being made would result
in beneficial ownership by such holder and its affiliates of more than 4.99% of
the outstanding shares of Common Stock. For purposes of this Section 7(g),
beneficial ownership shall be determined in accordance with Section 13(d) of the
Securities Exchange Act of 1934, as amended, and Regulation 13D-G thereunder.
Notwithstanding the foregoing, a holder may, by providing written notice to the
Company, (x) adjust the restriction set forth in this Section 7(g) so that the
limitations on beneficial ownership of 4.99% of the outstanding shares of Common
Stock referred to above shall not be applicable to such holder, which adjustment
shall not take effect until the 61st day after the date of such notice and (y)
irrevocably waive the right to deliver a waiver in accordance with this
sentence; provided, however, that if such adjustment would result in beneficial
ownership greater than 9.99% of the outstanding shares of Common Stock, by such
holder and its affiliates than such adjustment shall not take effect until the
75th day after the date of such notice.

       8      Registration Rights. The initial holder of this Warrant (and
certain assignees thereof) is entitled to the benefit of such registration
rights in respect of the Warrant Shares as are set forth in the Registration
Rights Agreement, including the right to assign such rights to certain
assignees, as set forth therein.

       9      Notices. Any notices required or permitted to be given under the
terms of this Warrant shall be sent by certified or registered mail (return
receipt requested) or delivered personally

                                      -13-
<PAGE>   14

or by courier or by confirmed telecopy, and shall be effective five days after
being placed in the mail, if mailed, or upon receipt or refusal of receipt, if
delivered personally or by courier, or by confirmed telecopy, in each case
addressed to a party. The addresses for such communications shall be:

                               If to the Company:

                               FastComm Communications
                               45472 Holiday Drive
                               Dulles, Virginia 20166
                               Telephone: (703) 318-7750
                               Telecopy:  (703) 787-4625
                               Attn: Peter C. Madsen, President

                               with a copy simultaneously transmitted by like
                               means to:

                               Sokolow, Dunaud, Mercadier & Carreras, LLP
                               770 Lexington Avenue - 6th Floor
                               New York, New York 10021-8165
                               Telephone: (212) 935-6000
                               Telecopy:  (212) 935-4865
                               Attn: Thomas G. Amon, Esq.

If to the holder, at such address as such holder shall have provided in writing
to the Company, or at such other address as such holder furnishes by notice
given in accordance with this Section 9.

       10     Governing Law; Jurisdiction. This Warrant shall be governed by and
construed in accordance with the laws of the State of New York applicable to
contracts made and to be performed in the State of New York. The Company
irrevocably consents to the jurisdiction of the United States federal courts
located in the City of New York in the State of New York in any suit or
proceeding based on or arising under this Warrant and irrevocably agrees that
all claims in respect of such suit or proceeding may be determined in such
courts. The Company irrevocably waives any objection to the laying of venue and
the defense of an inconvenient forum to the maintenance of such suit or
proceeding. The Company further agrees that service of process upon the Company
mailed by certified or registered mail shall be deemed in every respect
effective service of process upon the Company in any such suit or proceeding.
Nothing herein shall affect the holder's right to serve process in any other
manner permitted by law. The Company agrees that a final non-appealable judgment
in any such suit or proceeding shall be conclusive and may be enforced in other
jurisdictions by suit on such judgment or in any other lawful manner.

                                      -14-
<PAGE>   15

       11     Miscellaneous.

              (a)    Amendments. This Warrant and any provision hereof may only
be amended by an instrument in writing signed by the Company and the holder
hereof.

              (b)    Descriptive Headings.  The descriptive headings of the
several Sections of this Warrant are inserted for purposes of reference only,
and shall not affect the meaning or construction of any of the provisions
hereof.

              (c)    [Intentionally omitted].

              (d)    Business Day.  For purposes of this Warrant, the term
"business day" means any day, other than a Saturday or Sunday or a day on which
banking institutions in the State of New York are authorized or obligated by
law, regulation or executive order to close.

                            [SIGNATURE PAGE FOLLOWS]
       IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by
its duly authorized officer.

                                             FASTCOMM COMMUNICATIONS CORPORATION

                                             By: /s/ PETER C. MADSEN
                                                ---------------------
                                                Name: Peter C. Madsen
                                                Title: President

                                      -15-
<PAGE>   16
                           FORM OF EXERCISE AGREEMENT

         (TO BE EXECUTED BY THE HOLDER IN ORDER TO EXERCISE THE WARRANT)

To:    FastComm Communications
       45472 Holiday Drive
       Dulles, Virginia 20166
       Telephone: (703) 318-7750
       Telecopy:   (703) 787- 4625
       Attn: Peter C. Madsen, President

       The undersigned hereby irrevocably exercises the right to purchase
_____________ shares of the Common Stock of FASTCOMM COMMUNICATIONS CORPORATION,
a corporation organized under the laws of the Commonwealth of Virginia (the
"COMPANY"), evidenced by the attached Warrant, and herewith makes payment of the
Exercise Price with respect to such shares in full, all in accordance with the
conditions and provisions of said Warrant.

       (i)    The undersigned agrees not to offer, sell, transfer or otherwise
dispose of any Common Stock obtained on exercise of the Warrant, except under
circumstances that will not result in a violation of the Securities Act of 1933,
as amended, or any state securities laws, and agrees that the following legend
may be affixed to the stock certificate for the Common Stock hereby subscribed
for if resale of such Common Stock is not registered or if Rule 144 is
unavailable:

       THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
       REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR THE
       SECURITIES LAWS OF ANY STATE OF THE UNITED STATES. THE
       SECURITIES REPRESENTED HEREBY MAY NOT BE OFFERED OR SOLD IN THE
       ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT FOR THE
       SECURITIES UNDER APPLICABLE SECURITIES LAWS UNLESS OFFERED,
       SOLD OR TRANSFERRED PURSUANT TO AN AVAILABLE EXEMPTION FROM THE
       REGISTRATION REQUIREMENTS OF THOSE LAWS.

       (ii)   The undersigned requests that stock certificates for such shares
be issued, and a Warrant representing any unexercised portion hereof be issued,
pursuant to the Warrant in the name of the Holder and delivered to the
undersigned at the address set forth below:

Dated:
      ------------------                        --------------------------------
                                                      Signature of Holder

                                                --------------------------------
                                                      Name of Holder (Print)

                                                      Address:
                                                --------------------------------

                                                --------------------------------

                                                --------------------------------

<PAGE>   17

                               FORM OF ASSIGNMENT

       FOR VALUE RECEIVED, the undersigned hereby sells, assigns, and transfers
all the rights of the undersigned under the within Warrant, with respect to the
number of shares of Common Stock covered thereby set forth herein below, to:

Name of Assignee                  Address                           No of Shares

, and hereby irrevocably constitutes and appoints ______________________________
as agent and attorney-in-fact to transfer said Warrant on the books of the
within-named corporation, with full power of substitution in the premises.

Dated:
       ---------------------, ----

In the presence of

------------------

                                   Name:
                                        ----------------------------------------

                                        Signature:
                                                  ------------------------------
                                        Title of Signing Officer or
                                        Agent (if any):

                                                  ------------------------------
                                        Address:
                                                  ------------------------------
                                                  ------------------------------

                                        Note:  The above signature should
                                               correspond exactly with the name
                                               on the face of the within
                                               Warrant.<PAGE>   1
                                                                   EXHIBIT 10.9A

                                [ASC LETTERHEAD]

                                                                 August 30, 2000

New Enterprise Associates VIII, Limited Partnership
NEA Presidents' Fund, L.P.
NEA Ventures 1999, L.P.
TCV III (GP)
TCV III, L.P.
TCV III (Q), L.P.
TCV III Strategic Partners, L.P.
Morgan Stanley Venture Partners III, L.P.
Morgan Stanley Venture Investors III, L.P.
The Morgan Stanley Venture Partners Entrepreneur Fund, L.P.
Baker Communications Fund, L.P.
Mostafa Venture Fund, LLC
MCI Worldcom Venture Fund, Inc.

        RE:    IPO Purchase Rights

        Reference is made to the Securities Purchase and Stockholder Agreement,
dated as of September 10, 1999, as amended (the "Agreement"), among Advanced
Switching Communications, Inc. (the "Corporation"), Asghar Mostafa and the other
parties named therein (the "Investors") and the Letter regarding the Right to
Participate in Initial Public Offering of the same date, between the Corporation
and the Investors (the "Letter"). The Letter and Section 11.8 of the Agreement
provide that, in the event of a Qualified Initial Public Offering by the
Corporation, the holders of the Class C Preferred Shares and Class D Preferred
Shares shall have the option, on a pro rata basis, to purchase up to 5%, in the
aggregate, of the shares of capital stock offered by the Corporation ("IPO
Purchase Right"). Capitalized terms not defined herein shall have the meaning
assigned to them in the Agreement.

        In order to induce the Corporation to complete an initial public
offering of its common stock, each of the undersigned Investors has agreed to
waive its IPO Purchase

<PAGE>   2

Rights, provided that the offering is completed by November 30, 2000. If the
offering is not completed by November 30, 2000, all rights under Section 11.8
under the Agreement shall be reinstated. Whether or not the IPO actually occurs
depends on a number of factors, including market conditions.

        This letter agreement shall be governed by and construed in accordance
with the laws of the State of Delaware, without regard to principles of conflict
of laws, and may be executed in counterparts, each of which shall be deemed to
be an original but all of which together shall constitute one agreement.

                         [signatures on following pages]

<PAGE>   3

        Please acknowledge your agreement with the foregoing by executing this
letter in duplicate and returning one signed original to the Corporation as soon
as possible.

                                          ADVANCED SWITCHING
                                          COMMUNICATIONS, INC.

                                          By: /s/ ASGHAR MOSTAFA
                                              ----------------------------------
                                              Name: Asghar D. Mostafa
                                              Title: President + CEO

Accepted and agreed
as of August 10, 2000

NEW ENTERPRISE ASSOCIATES VIII, LIMITED PARTNERSHIP

By:  NEA Partners VIII, Limited Partnership

By:  /s/ ARTHUR MARKS
     -------------------------------
     Name: Arthur Marks
     Title:

NEW ENTERPRISE PRESIDENTS' FUND, L.P.

By:  NEA General Partnership, L.P.

By:  /s/ ARTHUR MARKS
     -------------------------------
     Name: Arthur Marks
     Title:

NEA VENTURES 1999, L.P.

By:  /s/ ARTHUR MARKS
     -------------------------------
     Name: Arthur Marks
     Title:

<PAGE>   4

TCV III (GP)

By: Technology Crossover Management III, L.L.C.
Its: General Partner

By:  /s/ CARLA S. NEWELL
     -------------------------------
     Name: Carla S. Newell
     Title: Attorney-in-Fact

TCV III, L.P.

By: Technology Crossover Management III, L.L.C.
Its: General Partner

By:  /s/ CARLA S. NEWELL
     -------------------------------
     Name: Carla S. Newell
     Title: Attorney-in-Fact

TCV III (Q), L.P.

By: Technology Crossover Management III, L.L.C.
Its: General Partner

By:  /s/ CARLA S. NEWELL
     -------------------------------
     Name: Carla S. Newell
     Title: Attorney-in-Fact

TCV III Strategic Partners, L.P.

By: Technology Crossover Management III, L.L.C.
Its: General Partner

By:  /s/ CARLA S. NEWELL
     -------------------------------
     Name: Carla S. Newell
     Title: Attorney-in-Fact

<PAGE>   5

MORGAN STANLEY VENTURE PARTNERS III, L.P.

By: Morgan Stanley Venture Partners III, L.L.C.
Its: General Partner

By: Morgan Stanley Venture Capital III, Inc.
Its:  Institutional Managing-Member

By:  /s/ GHASSAN BEJJANI
     -------------------------------
     Name: Ghassan Bejjani
     Title: Principal

MORGAN STANLEY VENTURE INVESTORS III, L.P.

By: Morgan Stanley Venture Partners III, L.L.C.
Its: General Partner

By: Morgan Stanley Venture Capital III, Inc.
Its: General Partner

By:  /s/ GHASSAN BEJJANI
     -------------------------------
     Name: Ghassan Bejjani
     Title: Principal

MORGAN STANLEY VENTURE PARTNERS ENTREPRENEUR FUND, L.P.

By: Morgan Stanley Venture Partners III, L.L.C.
Its: General Partner

By: Morgan Stanley Venture Capital III, Inc.
Its:  Institutional Managing Member

By:  /s/ GHASSAN BEJJANI
     -------------------------------
     Name: Ghassan Bejjani
     Title: Principal

<PAGE>   6

BAKER COMMUNICATIONS FUND, L.P.

By:  /s/ HENRY G. BAKER
     -------------------------------
     Name: Henry G. Baker
     Title: Manager of Baker Capital Partners, LLC
            its General Partner

MOSTAFA VENTURE FUND, LLC

By:  /s/ ASGHAR MOSTAFA
     -------------------------------
     Name:
     Title:

MCI WORLDCOM VENTURE FUND, INC.

By:  /s/ SUSAN MAYER
     -------------------------------
     Name: Susan Mayer
     Title: President

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