ABSTRACT
Modern routers are complex devices. The complexity is present in their hardware and software. Throughput and robustness as well as system availability requirements force router architects and designers to partition the functions as clearly as possible to simplify system design and testing. The function split is sometimes physical, sometimes logical, and sometimes both physical and logical. The function split can be between hardware and software, and between hardware and software modules. It can be such that a certain portion of software on a particular piece of hardware is a logical unit, and other portions of the hardware and software belong to other logical units. The function split pertains to data path functions as much as it does to control path functions.
