The Channel Interface Processor (CIP) provides up to two channel-attached interfaces for Cisco 7000 series and Cisco 7500 series routers, eliminating the need for a separate front-end processor. The CIP interfaces are combinations of a bus and tag (also called an original equipment manufacturer's interface [OEMI] and a parallel I/O interface) adapter and an Enterprise Systems Connection (ESCON) adapter. The bus and tag adapter is called the Parallel Channel Adapter (PCA), and the ESCON adapter is called the ESCON Channel Adapter (ECA). The PCA and ECA connect directly to the CIP, and any combination of the two adapters can be used.