The Cisco 3600 platform offers a wide variety of serial connectivity modules to accommodate the range of application needs in customer networks. The serial network module family for the Cisco 3600 series assures customers that they can choose a serial connectivity solution that fits their requirements. Available as network modules or WAN interface cards, serial connectivity options offer several port densities, synchronous and asynchronous alternatives, and integrated channel service unit/data service unit (CSU/DSU). As modular components, they are easily and inexpensively field upgradable as customer requirements change.The four-port asynchronous/synchronous serial network module available for the Cisco 3600 series provides flexible dial support, with each port configurable in synchronous or asynchronous mode, offering mixed-media dial support in a single chassis. In a typical WAN aggregation application, the Cisco 3640 platform can support up to 24 low-speed (up to 128 kbps) synchronous or asynchronous (up to 115.2 kbps) serial lines.