Challenges in Implementing an ESP Service

Although active network services have been widely studied, the task of mapping these services and algorithms onto actual network hardware presents an additional set of challenges. For example, high-end routers and switches are designed to handle as many interfaces delivering packets at wire speed as possible; in such an environment decentralized processing, pipelining, and efficient synchronization are crucial for good performance. At the low end (e.g. small routers/firewalls for the home), cost and flexibility are paramount; such systems are often structured as a general-purpose processor running modular software. Thus, the two environments are different and have different goals and objectives. We present a case study based on a representative active service called Ephemeral State Processing (ESP) that highlights many of the issues that arise when mapping services to real hardware. We discuss engineering considerations for ESP in both low-end uniprocessor and higher-end network processor scenarios, and present performance measurements from both implementations.