The Cisco CSS 11506 content services switch is a modular platform with interchangeable modules. The Cisco CSS 11506 requires at least one switch control module (SCM) and may be configured with a second in standby mode. With the required SCM in one slot, the CSS 11506 has five additional slots supporting any combination of I/O, Secure Sockets Layer, or session accelerator modules.The Cisco CSS 11506 supports not only redundancy in switch control modules but also redundant power supplies and redundant switch modules (20 Gbps each). All SCMs support redundant disk drives.