The < e1 > x < /e1 > -Kernel: an architecture for implementing network protocols

A description is given of an operating system kernel, called the < e1 > x < /e1 > -Kernel, that provides an explicit architecture for constructing and composing network protocols. The authors' experience implementing and evaluation several protocols in the < e1 > x < /e1 > -Kernel shows that this architecture is general enough to accommodate a wide range of protocols, yet efficient enough to perform competitively with less-structured operating systems. Experimental results demonstrating the architecture's generality and efficiency are provided. The explicit structure provided by the < e1 > x < /e1 > -Kernel has the following advantages. First, the architecture simplifies the process of implementing protocols in the kernel, making it easier to build and test novel protocols. Second, the uniformity of the interface between protocols avoids the significant cost of changing abstractions and makes protocol performance predictable. Third, it is possible to write efficient protocols by tuning the underlying architecture rather than heavily optimizing protocols themselves