In recent years, a significant amount of research work has addressed the use of code mobility in network management. In this paper, we introduce first three aspects of code mobility and argue that constrained mobility offers a natural and easy approach to network management programmability. While mobile agent platforms can support constrained mobility in a rather heavyweight fashion, optimized approaches such as our CodeShell platform presented here can provide performance and scalability comparable to those of static distributed object platforms such as Java-RMI and CORBA. Properly implemented constrained mobility is thus of great importance in network management, resulting in flexible, extensible, programmable systems without prohibitive performance overheads. Keywords. Code Mobility, Mobile Agents, Java-RMI, CORBA, Performance Evaluation