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                                                                   EXHIBIT 10.10

                                 HYDRIL COMPANY

                                 MODIFICATION TO

             AMENDMENT NO. 1 TO NOTE PURCHASE AGREEMENT AND CONSENT
                          UNDER INTERCREDITOR AGREEMENT

                                                              As of June 7, 2000

To each of the Current Noteholders
Named in Annex 1 hereto:

Ladies and Gentlemen:

                  Hydril Company, a Delaware corporation (hereinafter, the
"Company"), has entered into Amendment No. 1 to Note Purchase Agreement and
Consent under Intercreditor Agreement ("Amendment No. 1") with each of you,
dated as of the date hereof. Terms used and not defined herein have the meanings
ascribed thereto in Amendment No. 1.

1. MODIFICATION.

         Section 6 of Amendment No. 1 contains a consent of the Requisite
Noteholders to an increase in the line of credit permitted under the Bank
Agreement from $15,000,000 to $25,000,000, effective upon receipt by the Company
of not less than $40,000,000 in net proceeds from a public offering of its
common stock consummated at any time after the date of the Amendment No. 1. The
reference to "$40,000,000" in Section 6 of Amendment No. 1 is hereby deleted and
there is substituted therefor "$30,000,000".

2. EFFECTIVENESS OF MODIFICATION.

         The modification provided for in Section 1 hereof shall become
effective at such time as the Company and each of the Holders shall have
executed and delivered this Modification.

3. MISCELLANEOUS.

         3.1.  PART OF EXISTING NOTE AGREEMENT; FUTURE REFERENCES, ETC.

         This Modification shall be construed in connection with and as a part
of Amendment No. 1 and, except as expressly amended by this Modification, all
terms, conditions and covenants contained in Amendment No. 1 and the Existing
Note Agreement are hereby ratified and shall be and remain in full force and
effect. Any and all notices, requests, certificates and other instruments
executed and delivered after the execution and delivery of this Modification may
refer to the Existing Note Agreement without making specific reference to this
Modification, but nevertheless all such references shall include this
Modification unless the context otherwise requires.
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         3.2.  COUNTERPARTS.

         This Modification may be executed in any number of counterparts, each
of which shall be an original but all of which together shall constitute one
instrument. Each counterpart may consist of a number of copies hereof, each
signed by less than all, but together signed by all, of the parties hereto.

         3.3.  GOVERNING LAW.

         THIS MODIFICATION SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH,
AND THE RIGHTS OF THE PARTIES SHALL BE GOVERNED BY, THE LAW OF THE STATE OF NEW
YORK EXCLUDING CHOICE-OF-LAW PRINCIPLES OF THE LAW OF SUCH STATE THAT WOULD
REQUIRE THE APPLICATION OF THE LAWS OF A JURISDICTION OTHER THAN NEW YORK.

   [Remainder of page intentionally left blank; signature page(s) follow(s).]

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         If you are in agreement with the foregoing, please so indicate by
signing the acceptance below on the accompanying counterpart of this agreement
and returning it to the Company, whereupon it will become a binding agreement
among you and the Company.

                                       HYDRIL COMPANY

                                       By:        /s/ MICHAEL C. KEARNEY
                                          --------------------------------------
                                             Name:    Michael C. Kearney
                                             Title:   Vice President & CFO

                                       By:        /s/ ANDREW W. RICKS
                                          --------------------------------------
                                             Name:    Andrew W. Ricks
                                             Title:   Treasurer

                                       3
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The foregoing Modification is hereby accepted as of the date first above
written.

                              PRINCIPAL LIFE INSURANCE COMPANY

                                    By:   Principal Capital
                                    Management, LLC, a Delaware limited
                                    liability company, its authorized signatory

                                    By:          /s/ JON C. HEINY
                                       -----------------------------------------
                                    Name:            Jon C. Heiny
                                    Title:              Counsel

                                    By:        /s/ DENNIS D. BALLARD
                                       -----------------------------------------
                                    Name:          Dennis D. Ballard
                                    Title:              Counsel

                              PRINCIPAL LIFE INSURANCE COMPANY,
                              on behalf of one or more separate accounts

                                    By:   Principal Capital
                                    Management, LLC, a Delaware limited
                                    liability company, its authorized signatory

                                    By:          /s/ JON C. HEINY
                                       -----------------------------------------
                                    Name:            Jon C. Heiny
                                    Title:              Counsel

                                    By:        /s/ DENNIS D. BALLARD
                                       -----------------------------------------
                                    Name:          Dennis D. Ballard
                                    Title:              Counsel

                                       4
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                              NIPPON LIFE INSURANCE COMPANY
                              OF AMERICA, an Iowa corporation,
                              by its attorney in fact, Principal
                              Life Insurance Company, an
                              Iowa corporation

                                       By: /s/ JON C. HEINY
                                          --------------------------------------
                                       Name:  Jon C. Heiny
                                       Title: Counsel

                                       By: /s/ DENNIS D. BALLARD
                                          --------------------------------------
                                       Name:  Dennis D. Ballard
                                       Title: Counsel

                                       5<PAGE>   1
                                                                  EXHIBIT 10.10A

                                  AMENDMENT TO
                          KEY EMPLOYEE STOCK AGREEMENT

         THIS AMENDMENT TO KEY EMPLOYEE STOCK AGREEMENT (the "Amendment") is
made and entered into this __ day of August, 2000 by and between Advanced
Switching Communications, Inc., a Delaware corporation (the "Company"), and the
undersigned employee and stockholder of the Company (the "Key Employee").

         WHEREAS, the Company and the Key Employee are parties to a Key Employee
Stock Agreement (the "Agreement");

         WHEREAS, the Company has filed a registration statement with the
Securities and Exchange Commission in connection with a proposed initial public
offering of the Company's common stock (the "Initial Public Offering");

         WHEREAS, the parties desire to amend the Agreement to provide for the
termination of certain provisions of the Agreement following the closing of the
Initial Public Offering as set forth in this Amendment;

         NOW, THEREFORE, in consideration of the premises and for other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

         1.       Amendments

                  1.1.     Definition of Shares. Section 1 is hereby amended by
deleting paragraph (e) thereof in its entirety and substituting therefor the
following:

                  "'Shares' means (i) the shares of common stock of the Company
                  acquired by Key Employee in connection with the execution of
                  this Agreement, (ii) any subdivision of such Shares, (iii) the
                  payment of a dividend in Shares with respect to such Shares,
                  and/or (iv) any other securities issuable with respect to such
                  Shares without consideration or into which such Shares are
                  transformed as the result of a merger, consolidation, or
                  recapitalization."

                  1.2.     Definition of Initial Public Offering. Section 1 is
hereby amended by adding the following immediately following subsection 1(h):

                  "(i) "Initial Public Offering" shall mean the initial public
                  offering of the Company's common stock pursuant to an
                  effective registration statement under the Securities Act of
                  1933."
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         1.3.     The Company's Repurchase Rights. Section 4 of the Agreement is
hereby amended by designating the existing paragraph as subsection "(a)" and
adding the following paragraph as subsection "(b)":

                  "(b)     The Company's repurchase rights pursuant to Section
4(a) shall terminate:

                           (1)      with respect to 50% of the Shares,
                                    immediately after the closing of the Initial
                                    Public Offering;

                           (2)      with respect to 25% of the Shares, on the
                                    date six months after the closing of the
                                    Initial Public Offering; and

                           (3)      with respect to 25% of the Shares, on the
                                    date one year after the closing of the
                                    Initial Public Offering."

         1.4.     First Right of Refusal. Section 8 of the Agreement is hereby
amended by designating the existing paragraph as subsection "(a)" and adding the
following paragraph as subsection "(b)":

                  "(b)     The Company's rights of first refusal pursuant to
                  Section 8(a) shall terminate:

                           (1)      with respect to 50% of the Shares,
                                    immediately after the closing of the Initial
                                    Public Offering;

                           (2)      with respect to 25% of the Shares, on the
                                    date six months after the closing of the
                                    Initial Public Offering; and

                           (3)      with respect to 25% of the Shares, on the
                                    date one year after the closing of the
                                    Initial Public Offering."

         1.5.     The Agreement is hereby amended to add the following Section
                  14:

                           "14. Termination of Certain Rights Upon Completion of
                           IPO. Sections 5, 6 and 7 of this Agreement shall
                           terminate and be of no further force or effect
                           immediately upon the closing of the Company's Initial
                           Public Offering.

2.       Miscellaneous.

                  2.1.     No Other Amendment. As amended hereby the Agreement
                           shall remain in full force and effect.

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                  2.2.     Governing Law. This Amendment shall be governed by
                           the laws of the Commonwealth of Virginia.

                  2.3.     Counterparts. This Amendment may be executed in
                           counterparts.

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         IN WITNESS WHEREOF, the parties hereto have executed this Amendment as
of the date first written above.

                       ADVANCED SWITCHING COMMUNICATIONS, INC.

                       By:
                          ------------------------------------------------------
                       Name:
                       Title:

                       KEY EMPLOYEE:

                          ------------------------------------------------------
                               [Signature]

                       Name of Key Employee:
                                              ----------------------------------

                       Date of original
                       Key Employee Stock Agreement:
                                                      --------------------------

                       Number of Shares Covered
                      (adjusted to reflect stock splits):
                                                           ---------------------

                                   -4-

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