Exhibit 10.5.2

                                    AGREEMENT

      This Agreement is made as of July 25, 2002 by and between Visual Networks,
Inc. ("VN") and MCI WORLDCOM Network Services, Inc., for itself and its
Affiliates (collectively, "MCI"), with reference to that certain
Reseller/Integration Agreement between VN and MCI (together, the "Parties")
dated August 29, 1997, as amended (the "Reseller Agreement"). Capitalized terms
used but not defined in this Agreement have the meanings assigned to them in the
Reseller Agreement.

      WHEREAS, on July 21, 2002 (the "Petition Date"), WorldCom, Inc. and
substantially all of its active U.S. subsidiaries, including MCI, filed
petitions for relief under Chapter 11 of the United States Bankruptcy Code in
the United States Bankruptcy Court for the Southern District of New York (the
"Bankruptcy Court"), and

      WHEREAS, MCI wishes to purchase additional Products from VN during the
pendency of MCI's Chapter 11 case, and VN is willing to sell additional Products
to MCI on the terms and conditions set forth herein.

      NEW, THEREFORE, in consideration of the foregoing premises and the mutual
promises set forth herein, and for other good and valuable consideration, the
receipt and adequacy of which are hereby acknowledged, the Parties agree as
follows:

      1. Exhibit A to this agreement sets forth a list of Products that MCI
wishes to purchase from VN, and requested delivery dates for such Products. VN
agrees to use commercially reasonable efforts to ship the Products set forth on
Exhibit A on the Visual Committed Ship Dates specified on Exhibit A.

      2. All Products delivered by VN pursuant to the terms of Exhibit A shall
be invoiced at prices currently in effect under the Reseller Agreement, less an
additional discount equal to 0.5% (one-half of one percent) of VN's list prices
for such Products, plus any applicable taxes and shipping charges.

      3. Payment in full for all Products delivered by VN pursuant to this
Agreement must be received by VN within 15 calendar days after the Product
delivery date. There will be no further discount for early payment. If VN does
not receive payment when due under this agreement, VN shall have no obligation
to ship additional Products.

      4. VN shall have no obligation to ship Products other than those covered
by the purchase orders set forth on Exhibit A unless and until VN has received
payment for the Products shipped pursuant to Exhibit A. Sales of Products other
than under the purchase orders listed on Exhibit A will be subject to an overall
credit limit of $1.0 million.
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      5. To the extent of any inconsistency between the terms of this Agreement
and the terms of the Reseller Agreement, the terms of this Agreement shall
control.

      6. Within 90 days after the date of this Agreement, the Parties agree to
discuss in good faith the possibility of modifying the payment terms set forth
herein, but neither Party shall have any obligation to agree to any such
modification.

      IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed
by their duly authorized representatives as of the date set forth above.

                                        VISUAL NETWORKS, INC.

                                        By     /s/ John H. Saunders
                                               ---------------------------------
                                        Name:  John H. Saunders
                                        Title: Chief Financial Officer


                                        MCI WORLDCOM NETWORK SERVICES, INC.

                                        By     /s/ Frances McKissick
                                               ---------------------------------
                                        Name:  Frances McKissick
                                        Title: Senior Manager -  Procurement