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                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, DC  20549


                                  SCHEDULE 13G


                  Under the Securities Exchange Act of 1934
                            (Amendment No. ______*)




                               CIENA CORPORATION
  -----------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
  -----------------------------------------------------------------------------
                         (Title of Class of Securities)

                                   171779 10 1
  -----------------------------------------------------------------------------
                                 (CUSIP Number)

                                    12-31-00
  -----------------------------------------------------------------------------
            (Date of Event Which Requires Filing of this Statement)


        Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:


                               [X] Rule 13d-1(b)

                               [ ] Rule 13d-(c)

                               [ ] Rule 13d-1(d)



        *The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which would
alter the disclosures provided in a prior cover page.


        The information required in the remainder of this cover page shall not
be deemed to be "filed" for the purpose of Section 18 of the Securities
Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that
section of the Act, but shall be subject to all other provisions of the Act
(however, see the Notes).

        Potential persons who are to respond to the collection of information
contained in this form are not required to respond unless the form displays a
currently valid OMB control number.

SEC 1745 (3-98)

                                  Page 1 of 6
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 CUSIP NO. 171779 10 1                                                                    PAGE 2 OF 6 PAGES
     

-----------------------------------------------------------------------------------------------------------
|   1 | Names of Reporting Persons/I.R.S. Identification Nos. of Above Persons (Entities Only)            |
|     |                                                                                                   |
|     |                                                                                                   |
|     |Oak Associates ltd.                                                                                |
|-----|---------------------------------------------------------------------------------------------------|
|   2 | Check the Appropriate Box if a Member of a Group                                        (a) [ X ] |
|     | (See Instructions)                                                                          ----- |
|     |                                                                                         (b) [   ] |
|     |                                                                                             ----- |
|-----|---------------------------------------------------------------------------------------------------|
|   3 | SEC Use Only                                                                                      |
|     |                                                                                                   |
|-----|---------------------------------------------------------------------------------------------------|
|   4 | Citizenship or Place of Organization                                                              |
|     |                                                                                                   |
|     | Akron, Ohio; United States                                                                        |
|-------------------------------|-------|-----------------------------------------------------------------|
|            Number of          |     5 |  Sole Voting Power                                              |
|                               |       |                                                                 |
|             Shares            |       |  15,938,000                                                     |
|                               |-------|-----------------------------------------------------------------|
|          Beneficially         |     6 |  Shared Voting Power                                            |
|                               |       |                                                                 |
|            Owned by           |       |  0                                                              |
|                               |-------|-----------------------------------------------------------------|
|              Each             |     7 |  Sole Dispositive Power                                         |
|                               |       |                                                                 |
|            Reporting          |       |  0                                                              |
|                               |-------|-----------------------------------------------------------------|
|           Person With         |     8 |  Shared Dispositive Power                                       |
|                               |       |                                                                 |
|                               |       |  15,938,000                                                     |
|-------------------------------|-------|-----------------------------------------------------------------|
|   9 | Aggregate Amount Beneficially Owned by Each Reporting Person                                      |
|     |                                                                                                   |
|     | 15,938,000                                                                                        |
|-----|---------------------------------------------------------------------------------------------------|
|  10 | Check if the Aggregate Amount in Row (9) Excludes Certain Shares                                  |
|     | (See Instructions)                                                                          [   ] |
|     |                                                                                             ----- |
|-----|---------------------------------------------------------------------------------------------------|
|  11 | Percent of Class Represented by Amount in Row (9)                                                 |
|     |                                                                                                   |
|     | 5.57%                                                                                             |
|-----|---------------------------------------------------------------------------------------------------|
|  12 | Type of Reporting Person (See Instructions)                                                       |
|     |                                                                                                   |
|     | IA                                                                                                |
-----------------------------------------------------------------------------------------------------------

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CUSIP NO. 171779 10 1               13G                      PAGE 3 OF 6 PAGES

ITEM 1
       (a)   Name of Issuer:

             Ciena Corporation

       (b)   Address of Issuer's Principal Executive Offices:

             920 Elkridge Landing Rd.
             Linthicum, MD 21090

ITEM 2
       (a)   Name of Person Filing:

             Oak Associates, ltd.

       (b)   Address of Principal Business Office:

             3875 Embassy Pkwy, Akron, OH 44333

       (c)   Citizenship:

             United States of America

       (d)   Title of Class of Securities:

             Common Stock

       (e)   CUSIP Number:

             171779 10 1

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CUSIP NO. 171779 10 1               13G                    PAGE 4 OF 6 PAGES

ITEM 3.      IF THIS STATEMENT IF FILED PURSUANT TO RULE 240.13d-1(b), OR
             240.13d-2(b) OR (c), CHECK WHETHER THE PERSON FILING IS A:


             (a) [ ] Broker or dealer registered under Section 15 of the
                     Act (15 U.S.C. 78o).

             (b) [ ] Bank as defined in Section 3(a)(6) of the Act
                     (15 U.S.C. 78c).

             (c) [ ] Insurance company as defined in Section 3(a)(19) of
                     the Act (15 U.S.C. 78c).

             (d) [ ] Investment company registered under Section 8 of the
                     Investment Company Act of 1940 (15 U.S.C 80a-8).

             (e) [X] An investment adviser in accordance with
                     240.13d-1(b)(1)(ii)(E).

             (f) [ ] An employee benefit plan or endowment fund in accordance
                     with 240.13d-1(b)(1)(ii)(F).

             (g) [ ] A parent holding company or control person in accordance
                     with 240.13d-1(b)(1)(ii)(G).

             (h) [ ] A savings association as defined in Section 3(b) of the
                     Federal Deposit Insurance Act (12 U.S.C. 1813).

             (i) [ ] A church plan that is excluded from the definition of an
                     investment company under Section 3(c)(14) of the Investment
                     Company Act of 1940 (15 U.S.C. 80a-3).

             (j) [ ] Group, in accordance with Section 240.13d-1(b)(1)(ii)(J).

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CUSIP NO. 171779 10 1               13G                      PAGE 5 OF 6 PAGES

ITEM 4.  OWNERSHIP.

        (a)     Amount beneficially owned: 15,938,000.

        (b)     Percent of class: 5.57%.

        (c)     Number of shares as to which the person has:

ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.

        If this statement is being filed to report the fact that as of the date
hereof the reporting person has ceased to be the beneficial owner of more than
five percent of the class of securities, check the following [ ].


ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.
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CUSIP NO. 171779 10 1               13G                      PAGE 6 OF 6 PAGES


ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE
        SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY.


ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP.


ITEM 9.   NOTICE OF DISSOLUTION OF GROUP.


ITEM 10.  CERTIFICATIONS.

By signing below I certify that, to the best of my knowledge and belief, the
securities referred to above were acquired and are not held for the purpose of
or with the effect of changing or influencing the control of the issuer of the
securities and were not acquired and are not held in connection with or as a
participant in any transaction having that purpose or effect.



DATED:                                   By: /s/ JAMES D. OELSCHLAGER
                                             -------------------------------
                                             Name:  James D. Oelschlager
                                             Title: Managing Director