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                                                                  EXHIBIT 10.5.1

                          AGREEMENT AND GENERAL RELEASE

         This Separation Agreement and General Release (hereinafter "Agreement")
is made and entered into by and between Allied Riser Communications Corporation
("ARCC") and Allied Riser Operations Corporation ("AROC") (which may be
collectively referred to as "the Company"), and Mr. David Crawford (hereinafter
"Mr. Crawford").

              1.     PRELIMINARY STATEMENT. The intent of this Agreement is to
                     mutually, amicably and finally resolve and compromise all
                     issues and claims related to the employment of Mr. Crawford
                     with the Company and the separation of Mr. Crawford from
                     such employment, including (but not limited to) those
                     arising from the Employment Agreement between Mr. Crawford
                     and the Company dated July 15, 1997, as amended by the
                     Letter Agreement dated September 19, 2000 ("Employment
                     Agreement"), the terms of which are incorporated herein by
                     reference. This agreement shall not in any way be construed
                     as an admission by either party that such party has acted
                     wrongfully with respect to the other party or any other
                     person.

              2.     RESIGNATION OF MR. CRAWFORD AS DIRECTOR, OFFICER AND
                     EMPLOYEE. The parties agree that effective October 13,
                     2000, Mr. Crawford resigns as a director, officer and
                     employee of the Company and its affiliates and
                     subsidiaries.

              3.     POST-TERMINATION BENEFITS. In consideration for Mr.
                     Crawford's releases, waivers and covenants contained in
                     this Agreement, and in lieu of any and all other monies,
                     payments, or other rights to which Mr. Crawford may claim
                     entitlement, including any bonus for 2000, the Company
                     agrees: (a) to pay Mr. Crawford a severance amount of
                     $600,000, minus applicable deductions, (b) to vest Mr.
                     Crawford in all shares of Restricted Shares previously
                     purchased by him and all Stock Options in which he was not
                     vested prior to the termination of his employment (leaving
                     him with 623,737 total vested Restricted Shares and 400,000
                     total vested Stock Options), subject to the provisions of
                     the Subscription Agreement between Mr. Crawford and RCH
                     Holdings, Inc. ("Subscription Agreement"), and other
                     applicable agreements relating to his receipt of Restricted
                     Shares and Stock Options, each of which is incorporated
                     herein by reference, (c) to reimburse any expenses incurred
                     by Mr. Crawford related to Company business on or before
                     November 13, 2000.

              4.     MUTUAL RELEASE, DISCHARGE, WAIVER AND COVENANT NOT TO SUE.
                     The Company and Mr. Crawford, on behalf of themselves and
                     anyone claiming for them, including without limitation
                     spouses, heirs, executors, administrators, children,
                     assigns, parent companies, and affiliates, fully release,
                     discharge and covenant not to sue the other, their current
                     and former officers, directors, shareholders, employees,
                     attorneys, agents, subsidiaries, affiliates, related
                     organizations,



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                     executors, estates, successors and assigns with respect to
                     and from, any claims and demands, whether known or unknown
                     or contingent or absolute, that either has, may have or
                     claims to have prior to the date of signature of this
                     Agreement, or as a result of the termination of Mr.
                     Crawford's employment by the Company or any of its current
                     or former affiliated organizations, divisions or
                     operational subdivisions.

                     This release, discharge, waiver and covenant not to sue
                     includes, but is not limited to, all claims and any
                     obligations or causes of action arising from such claims
                     which could have been raised under common law, including
                     wrongful or retaliatory discharge, breach of contract,
                     fraud, misrepresentation, breach of fiduciary duty,
                     promissory estoppel and any action arising in tort
                     including libel, slander, defamation or intentional
                     infliction of emotional distress, and claims under any
                     statute including Title VII of the Civil Rights Act of
                     1964, as amended, 42 U.S.C. Section 2000e, et seq., the
                     Civil Rights Acts of 1886 and 1871, 42 U.S.C. Section 1981,
                     et seq., the National Labor Relations Act, 29 U.S.C.
                     Section 151, et seq., the Age Discrimination in Employment
                     Act, 29 U.S.C. Section 621, et seq., as amended, including
                     the Older Workers Benefit Protection Act, the Fair Labor
                     Standards Act, 29 U.S.C. Section 201, et seq., the Employee
                     Retirement Income Security Act, 29 U.S.C. Section 1001, et
                     seq., the Americans With Disabilities Act and any other
                     federal, state or municipal law or ordinance relating to
                     employment, benefits or pay whether express or implied or
                     in contract law or tort.

              5.     RETURN OF THE COMPANY'S PROPERTY AND PRESERVATION OF
                     CONFIDENTIALITY. Mr. Crawford shall return to the Company
                     all notes, reports, sketches, plans, books, keys,
                     unpublished memoranda or other documents or property
                     ("Company property") which were created, developed and
                     generated by Mr. Crawford during his employment which are
                     related to the Company's business, whether or not
                     containing or relating to confidential information.

              6.     CONFIDENTIALITY AGREEMENT. It is the express intent of the
                     parties that the terms and conditions of this Agreement
                     shall be kept confidential except as set out in this
                     Agreement. The parties agree that Mr. Crawford may disclose
                     the terms of this Agreement only to his spouse, his
                     attorneys, and to his accountants or appropriate
                     authorities for tax purposes. The parties also agree that
                     the Company may disclose the terms of this Agreement to its
                     officers, directors, attorneys and to those employees who
                     are necessary to carry out the terms of this Agreement and
                     to the public or to government agencies to the extent
                     required by law.

              7.     NONDISPARAGEMENT. The parties agree that neither Mr.
                     Crawford nor the Company will engage in any conduct or take
                     any action, written or oral, that will reflect negatively
                     on or harm the business interest of the other party. The
                     Company will not take any action to interfere or prevent
                     Mr. Crawford from obtaining new employment.

              8.     DISPUTE RESOLUTION. In the event any controversy or dispute
                     arises in connection with the validity, construction,
                     application, enforcement or breach of this

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                     Agreement, any such controversy or dispute shall be
                     submitted to final and binding arbitration pursuant to the
                     commercial arbitration rules of the American Arbitration
                     Association and the United States Arbitration Act and the
                     parties hereto expressly waive their rights, if any, to
                     have any such matters heard by a court or a jury, or
                     administrative agency, whether state or federal. The
                     arbitrator shall require the losing party to reimburse the
                     prevailing party for reasonable attorneys' fees and costs
                     incurred in connection with the arbitration. The losing
                     party shall also be required to pay the arbitrator's fees
                     for said arbitration. Provided, however, that nothing
                     contained in this Section 8 shall preclude the Company from
                     seeking temporary or permanent relief to enjoin Mr.
                     Crawford's actual or threatened violation of Sections 5 and
                     6 of this Agreement, Sections 4 and 5 of the Employment
                     Agreement, and Section 6 of and Exhibit B to the
                     Subscription Agreement, or of statutory or common law
                     rights and obligations concerning the subject matter of any
                     such provisions.

              9.     SEVERABILITY. The terms and provisions of this Agreement
                     shall be deemed separable, so that if any term or provision
                     is deemed to be invalid or unenforceable, such term or
                     provision shall be deemed deleted or modified so as to be
                     valid and enforceable to the full extent permitted by
                     applicable law.

              10.    GOVERNING LAW. This Agreement shall be construed in
                     accordance with laws governing contracts made and to be
                     performed in the State of Texas.

              11.    SUCCESSORS AND ASSIGNS. This Agreement shall inure to the
                     benefit of and may be enforced by the parties to this
                     Agreement and shall be binding upon Mr. Crawford, his
                     executors, administrators, legatees, or any other successor
                     in interest and upon ARCC, AROC, their successors and any
                     assignee or transferee of or successor to all or
                     substantially all of the business or assets of AROC and may
                     not be amended, in whole or in part, except in writing
                     signed by Mr. Crawford and an authorized agent of ARCC and
                     AROC.

              12.    KNOWING AND VOLUNTARY. Mr. Crawford also agrees that:

                     a.     He enters into this Agreement knowingly and
                            voluntarily;

                     b.     He has read and understands this Agreement in its
                            entirety;

                     c.     He has been advised and directed to seek legal
                            counsel with respect to the terms of this Agreement
                            before executing it;

                     d.     His execution of this Agreement has not been forced
                            or coerced by any employee or agent of the Company
                            in any way;

                     e.     He was provided the opportunity to take 21 calendar
                            days after receipt of this Agreement to consider its
                            terms before he executed it;

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                     f.     That the consideration provided constitute
                            consideration greater than that to which he is
                            otherwise entitled at termination;

                     g.     That if either Party breaches this Agreement by
                            filing a legal action against the other contrary to
                            any release set forth in Paragraph 4 the breaching
                            Party will reimburse the other for costs and
                            reasonable attorneys' fees incurred in defending
                            such action. Further, if Mr. Crawford breaches this
                            Agreement by filing a legal action contrary to any
                            release set forth in Paragraph 4, he must first
                            return the separation payments he has received
                            pursuant to Paragraph 3 of this Agreement and he
                            will not be entitled to any further separation
                            payments under this Agreement. Nothing contained in
                            this Paragraph 12 shall be construed to prevent the
                            enforcement of the terms of this Agreement pursuant
                            to Paragraph 8.

              13.    REVOCATION. For a period of seven (7) days following the
                     execution of this Agreement, Mr. Crawford may revoke this
                     Agreement and this Agreement shall not become effective or
                     enforceable until the revocation period expires. Revocation
                     can be made by delivering written notice to Mr. Michael
                     Carper, AROC's Vice President and General Counsel, 1700
                     Pacific Avenue, Suite 400, Dallas, Texas 75201. For this
                     revocation to be effective, written notice must be received
                     by Mr. Carper no later than the close of business on the
                     seventh (7th) day after the signing of this Agreement. If
                     Mr. Crawford revokes this Agreement, it shall not be
                     effective or enforceable and Mr. Crawford will not receive
                     the benefits described in Paragraph 3.

              14.    ENTIRE AGREEMENT. The terms of this Agreement constitute
                     the entire understanding and agreement of the parties on
                     the subjects covered, and may not be modified except in
                     writing signed by both parties. The parties agree, however,
                     that except as expressly set forth in this Agreement, the
                     terms of this Agreement do not modify any continuing
                     obligations which Mr. Crawford may owe ARCC or AROC and its
                     affiliates and subsidiaries under existing agreements with
                     the Company or its affiliates or subsidiaries, including
                     (but not limited to) obligations under Sections 4 and 5 of
                     the Employment Agreement and Section 6 of and Exhibit B to
                     the Subscription Agreement.

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IN WITNESS WHEREOF, the parties have executed this Agreement as of the date
indicated below.



/s/ David Crawford                    ALLIED RISER COMMUNICATIONS
------------------------------                CORPORATION
David Crawford

Date:    November 16, 2000            By:    /s/ Michael R. Carper
                                            -----------------------------------
                                      Name:  Michael R. Carper
                                            -----------------------------------
                                      Title: Vice President
                                            -----------------------------------
                                      Date:  11/16/00
                                            -----------------------------------


                                      ALLIED RISER OPERATIONS CORPORATION


                                      By:    /s/ Michael R. Carper
                                            -----------------------------------
                                      Name:  Michael R. Carper
                                            -----------------------------------
                                      Title: Vice President
                                            -----------------------------------
                                      Date:  11/16/00
                                            -----------------------------------



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