The 21400 appliance has 3 expansion slots supporting a wide range of network options. The standard configuration includes one on-board 10/100/1000 RJ-45 Management port and a twelve 1 Gigabit Ethernet copper port card. A maximally configured 21400 provides up to 37 Gigabit Ethernet copper ports or 36 fiber ports or twelve 10 Gigabit Ethernet fiber ports.

The 21400 appliance chassis is highly serviceable. Access to all components is available from the front and the back of the unit when mounted in the rack. There is one slot for an optional Security Acceleration Module to boost performance of the appliance. In addition to hot-swappable redundant disk drives and power supply units, the 21400 appliance also supports Lights-Out-Management (LOM) for remote support and maintenance capabilities.