VOID AFTER 5:00 P.M. NEW YORK CITY
               TIME ON [INSERT DATE]                              EXHIBIT B
                                                                  to Securities
                                                                  Purchase
                                                                  Agreement

               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. THE SECURITIES  REPRESENTED HEREBY MAY NOT BE OFFERED,
               SOLD  OR  OTHERWISE   TRANSFERRED   UNLESS  THE   SECURITIES  ARE
               REGISTERED   UNDER  THE  SECURITIES  ACT  AND  APPLICABLE   STATE
               SECURITIES  LAWS,  OR ANY SUCH  OFFER,  SALE OR  TRANSFER IS MADE
               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: _________ ___, _____

                       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 Virginia corporation (the "Company"), at any time or from time to
time  during the period  specified  in Section 2 hereof,  ___________  (_______)
fully paid and  nonassessable  shares of the Company's  common stock,  par value
$.01 per share  (the  "Common  Stock"),  at an  exercise  price  per share  (the
"Exercise  Price")  equal to one hundred and twenty five  percent  (125%) of the
Market Price (as defined in Section  4(1)(ii) hereof) of the Common Stock on the
date of  issuance  hereof.  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 upon  conversion of (i) the
Company's  convertible  debentures due April 9, 2001 (the "Debentures") and (ii)
shares of Series A Convertible Preferred Stock of the Company.




     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 any part consisting of not less than ten percent (10%) of
the then issuable  Warrant  Shares,  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 (i)
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 or (ii) if the resale of the Warrant
Shares  by  the  holder  is  not  then  registered   pursuant  to  an  effective
registration  statement  under  the  Securities  Act of 1933,  as  amended  (the
"Securities Act"), delivery to the Company of a written notice of an election to
effect a Cashless  Exercise (as defined in Section  11(c) below) 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. Certifi cates 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 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.

     If, at any time, a holder of this Warrant submits this Warrant, an Exercise
Agreement  and  payment  to the  Company of the  Exercise  Price for each of the
Warrant  Shares  specified in the Exercise  Agreement,  and the Company does not
have  sufficient  authorized  but unissued  shares of Common Stock  available to
effect such  exercise in  accordance  with the  provisions of this Section 1 (an
"Exercise Default"),  the Company shall issue to the holder all of the shares of
Common Stock which are available to effect such  exercise  and,  within five (5)
business  days of the attempted  exercise of this Warrant,  refund to the holder
that portion of the  holder's  payment of the  Exercise  Price  allocable to the
number of shares  of Common  Stock  included  in the  Exercise  Agreement  which
exceeds the amount which is then issuable by the Company (the "Excess  Amount").
The Excess  Amount  shall,  notwithstanding  anything to the contrary  contained
herein,  not be exercisable for Common Stock in accordance with the terms hereof
until (and at the holder's option on or at any


                                      -2-


time after) the date  additional  shares of Common Stock are  authorized  by the
Company to permit such  exercise.  The Company shall pay to the holder  payments
("Exercise  Default  Payments")  for an  Exercise  Default  in the amount of (a)
(N/365),  multiplied by (b) the difference  between the Market Price (as defined
in Section 4(1) below) on the Exercise  Default Date (as defined below) less the
Exercise  Price,  multiplied  by (c) the Excess  Amount on the date the Exercise
Agreement  giving rise to the Exercise Default is transmitted in accordance with
this Section 1 (the "Exercise  Default Date"),  multiplied by (d) .24, where N =
the  number  of  days  from  the   Exercise   Default  Date  to  the  date  (the
"Authorization  Date") that the Company authorizes a sufficient number of shares
of Common Stock to effect  exercise of this Warrant in full.  The Company  shall
send notice to the holder of the  authorization  of additional  shares of Common
Stock,  the  Authorization  Date and the  amount of  holder's  accrued  Exercise
Default  Payments.  The accrued Exercise Default Payment for each calendar month
shall be paid in cash or shall be convertible  into Common Stock at the Exercise
Price, at the holder's option, as follows:

          (a) In the event  holder  elects to take such  payment  in cash,  cash
payment  shall be made to holder by the fifth  (5th) day of the month  following
the month in which it has accrued; and

          (b) In the event holder  elects to take such payment in Common  Stock,
the holder may convert  such  payment  amount into Common  Stock at the Exercise
Price (as in effect at the time of conversion) at any time after the fifth (5th)
day of the month  following  the month in which it has  accrued as  computed  in
accordance with the terms contained in Article VI of the Debentures.

          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  4(f) of that
certain Securities Purchase Agreement, dated as of April 9, 1997, by and between
the  Company  and the  purchaser  listed  on the  execution  page  thereof  (the
"Securities Purchase  Agreement"),  or to otherwise issue shares of Common Stock
upon  exercise of this Warrant in  accordance  with the terms  hereof,  and each
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. This Warrant is exercisable at any time or from time
to time on or after the date on which this  Warrant  is issued  and before  5:00
p.m. New York City time on the fifth (5th)  anniversary  of the date of issuance
(the "Exercise Period").


                                      -3-


     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 of this Warrant.

          (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 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 exercise privilege of the holder of this Warrant
against dilution or other  impairment,  consistent with the tenor and purpose of
this Warrant as specified in Section 4 below.  Without  limiting the general ity
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.


                                      -4-


     4. Antidilution Provisions. After the initial issuance of this Warrant, the
Exercise  Price and the number of Warrant  Shares 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 and Number of Shares upon Issuance of
Common Stock.  Except as otherwise provided in Sections 4(c) and 4(e) hereof, if
and whenever after the initial  issuance of this Warrant,  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;
   E    =   the then current Exercise Price;
   M    =   the then current Market Price (as defined in Section 4(1));
   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)) 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 on


                                      -5-


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.

                    (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 on the date of issuance, 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.


                                      -6-


                    (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
(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
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


                                      -7-


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 date of issuance hereof
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 grant of such stock or options is made
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  Preferred  Stock in
accordance  with terms of the  Securities  Purchase  Agreement or Warrants  upon
conversion of such Preferred Stock; or (iv) upon the exercise of the Warrants or
conversion of the Preferred Stock.

          (c) Subdivision or Combination of Common Stock. If the Company, at any
time after the initial issuance of this Warrant, 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 after the initial  issuance of this Warrant,  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 shall be adjusted
by multiplying a number equal to the Exercise Price


                                      -8-


in effect immediately prior to such adjustment by the number of shares of Common
Stock  issuable  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 after the initial issuance of this Warrant, 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  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
Section 4 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.

          (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,  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 after the initial issuance of this
Warrant, 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 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.


                                      -9-


          (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;

               (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  approximation  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 30 days
prior to the record date


                                      -10-


or the  date on which  the  Company's  books  are  closed  in  respect  thereto;
provided,  however,  that the Company  shall not be  required  to  disclose  any
material  information  to the  holder  hereof  prior  to the  public  disclosure
thereof.  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) Certain Events. If, at any time after the initial issuance of this
Warrant, any event occurs of the type contemplated by the adjustment  provisions
of this Section 4 but not expressly provided for by such provisions, the Company
will give  notice of such event as  provided  in Section  4(g)  hereof,  and the
Company's Board of Directors will make an appropriate adjustment in the Exercise
Price and the number of shares of Common Stock  acquirable upon exercise of this
Warrant  so that  the  rights  of the  holder  shall  be  neither  enhanced  nor
diminished by such event.

          (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
National Market for the ten (10) consecutive trading days immediately  preceding
such date, or (ii) if the Nasdaq  National  Market is not the principal  trading
market for the shares of Common  Stock,  the  average of the last  reported  bid
prices on the  principal  trading  market for the Common  Stock  during the same
period,  or, if there is no bid price for such period,  the last reported  sales
price for such period,  or (iii) 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 Corporation and reasonably  acceptable to the holder,  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


                                      -11-


dividends or distributions on liquidation,  provided that the shares purchasable
pursuant to this Warrant  shall  include only Common  Stock,  par value $.01 per
share, 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.

     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 Section 7(f) and (g) hereof and to the provisions of
Sections 2(f) and 2(g) of the Securities Purchase Agreement;  provided, further,
however,  that the  Warrants  may not be  transferred  to more than  twenty five
transferees in the aggregate. 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 April 9, 1997,  by and among the Company and the
other signatory 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


                                      -12-


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.

     (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.

     (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,  (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,
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.  Notwithstanding
anything  contained herein to the contrary,  in no event shall the holder hereof
exercise Warrants to the extent


                                      -13-


that (a) the number of shares of Common Stock  beneficially owned by such holder
and its  affiliates  (other  than  shares  of Common  Stock  which may be deemed
beneficially  owned  through the  ownership  of the  unexercised  portion of the
Warrants  or the  unexercised  or  unconverted  portion of any other  securities
(including, without limitation, the Preferred Stock) of the Company subject to a
limitation  on  conversion  or exercise  analogous to the  limitation  contained
herein) and (b) the number of shares of Common Stock  issuable  upon exercise of
the  Warrants  (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 4.9% of the outstanding  shares of Common
Stock. For purposes of the immediately preceding sentence,  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,  except as otherwise
provided in clause (a) hereof.  The first holder of this Warrant,  by taking and
holding the same,  represents to the Company that such holder is acquiring  this
Warrant for  investment  only and not with a view to the  distribution  thereof,
except pursuant to sales that are exempt from the  registration  requirements of
the Securities Act and/or sales registered under the Securities Act.

     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.

     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 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
confirmed  telecopy,  in each case addressed to a party.  The addresses for such
communications shall be:

                        If to the Company:

                        FastComm Communications Corporation
                        45472 Holiday Drive
                        Sterling, VA 20166
                        Telecopy: (703) 318-4315
                        Attn: Chief Financial Officer


                                      -14-


                          with copy to:

                          Amon & Sabatini, L.L.P.
                          437 Madison Avenue
                          New York, NY 10022
                          Telecopy: (212) 980-3075
                          Attn: Thomas Amon, Esquire

and if to the  holder,  at such  address as such holder  shall have  provided in
writing to the Company, or at such other address as each such party 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 New York,  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 the defense of an  inconvenient  forum to the maintenance of such suit or
proceeding.  The Company  agrees that service of process upon the Company mailed
by first  class  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.

     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)  Cashless  Exercise.  Notwithstanding  anything  to  the  contrary
contained in this Warrant,  if the resale of the Warrant Shares by the holder is
not then registered  pursuant to an effective  registration  statement under the
Securities  Act, this Warrant may be exercised at any time after the first (1st)
anniversary  of the  date  hereof  until  the  end of the  Exercise  Period,  by
presentation  and  surrender  of this  Warrant to the  Company at its  principal
executive  offices with a written  notice of the holder's  intention to effect a
cashless exercise, including a calculation of the number of shares


                                      -15-


of Common  Stock to be issued upon such  exercise in  accordance  with the terms
hereof (a "Cashless Exercise").  In the event of a Cashless Exercise, in lieu of
paying the Exercise Price in cash,  the holder shall  surrender this Warrant for
that number of shares of Common Stock  determined by  multiplying  the number of
Warrant  Shares to which it would  otherwise  be  entitled  by a  fraction,  the
numerator of which shall be the difference between the then current Market Price
per share of the Common Stock and the Exercise  Price,  and the  denominator  of
which shall be the then current Market Price per share of Common Stock.

          (d) Force Majeure.  Neither the Company nor the holder hereof shall be
responsible  for any delay or failure to perform any part of this Warrant to the
extent that such delay or failure is solely caused by fire,  flood,  earthquake,
explosion,  war,  labor strike,  riot,  act of  governmental,  civil or military
authority  which  imposes  a  moratorium  on the  performance  of  the  specific
obligation  in  question  or other  comparable  extraordinary  event  beyond the
Company's or holder's control.  Notice with full details of any such event shall
be given to the other party as promptly as practicable after its occurrence. The
affected  party shall use its best efforts to minimize the effects of or end any
such event so as to facilitate the resumption of full performance hereunder.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]


                                      -16-


     IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by its
duly authorized officer.

                                        FASTCOMM COMMUNICATIONS
                                        CORPORATION


                                        By: ________________________
                                            Name:___________________
                                            Title:____________________


                                      -17-


                           FORM OF EXERCISE AGREEMENT

         (To be Executed by the Holder in order to Exercise the Warrant)


     The  undersigned  hereby  irrevocably   exercises  the  right  to  purchase
_____________  of  the  shares  of  common  stock  of  FastComm   Communications
Corporation,  a Virginia corporation (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(k) is
unavailable:

          THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
          REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. THE
          SECURITIES  HAVE BEEN ACQUIRED FOR INVESTMENT AND MAY NOT BE
          SOLD, TRANSFERRED OR ASSIGNED IN THE ABSENCE OF AN EFFECTIVE
          REGISTRATION STATEMENT FOR THE SECURITIES UNDER SAID ACT, OR
          AN  OPINION  OF  COUNSEL,  IN  FORM,   SUBSTANCE  AND  SCOPE
          CUSTOMARY    FOR   OPINIONS   OF   COUNSEL   IN   COMPARABLE
          TRANSACTIONS,  THAT  REGISTRATION IS NOT REQUIRED UNDER SAID
          ACT OR UNLESS SOLD PURSUANT TO RULE 144(K) UNDER SAID ACT.


     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:
                                           _____________________________________
                                           _____________________________________
                                           _____________________________________
                                          
                                          


                               FORM OF ASSIGNMENT

     FOR VALUE RECEIVED,  the undersigned hereby sells,  assigns,  and transfers
all the rights of the  undersigned  under the within Warrant in accordance  with
the  conditions  and  provisions of said Warrant,  with respect to the number of
shares of Common Stock covered thereby set forth hereinbelow, 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.