EXHIBIT 21.01 SUBSIDIARIES Concord Communications Securities Corporation 600 Nickerson Road Marlborough, MA 01752 State of incorporation: Massachusetts Concord Communications International, Inc. 600 Nickerson Road Marlborough, MA 01752 State of incorporation: Delaware CCA Holdings, Inc. 600 Nickerson Road Marlborough, MA 01752 State of incorporation: Delaware FirstSense Software, Inc. 600 Nickerson Road Marlborough, MA 01752 State of incorporation: Delaware Concord Communications FSC, Ltd. 600 Nickerson Road Marlborough, MA 01752 Organized under the laws of: Bermuda NetViz LLC 600 Nickerson Road Marlborough, MA 01752 State of incorporation: Delaware Vitel Software, Incorporated 600 Nickerson Road Marlborough, MA 01752 State of incorporation: Massachusetts Aprisma Holdings, Inc. 600 Nickerson Road Marlboro, MA 01752 State of incorporation: Delaware