The single, hot-pluggable network interface unit (NIU) contains all of the Acme Packet 4600 media and management interfaces. The NIU is located on the Acme Packet 4600 rear panel. The Signaling, Media and Network Management interfaces are located on the front panel of the NIU.

Without powering down the hot-swappable Acme Packet 4600 you can exchange an NIU by removing and replacing it. Upon removal of the NIU, the Acme Packet 4600 enters an Out-of-Service state. After you reinsert the NIU and connect to the ACLI, you must reboot the system to return to service. This causes a soft reboot rather than a system power cycle.

Each of the NIU front panel components are described in the following subsections.