The Tellabs 1150 can be equipped with Ethernet Switch Unit (ESU11) or Ethernet Switch Unit Two (ESU2). ESU11 is implemented with non-blocking 24 Gbps switch fabric and four 1GbE Small Form-factor Pluggable (SFP) optics based IP/Ethernet interfaces. ESU2 provides a non-blocking 200 Gbps switch fabric, two 10GbE XFP based and four 1GbE SFP based IP/Ethernet interfaces. This ESU can be deployed redundantly for highest resiliency and reliability. System timing is controlled by redundant Timing Distribution Unit (TDU) cards in the Tellabs 1150 shelf. Alarm Maintenance Unit (AMU) provides alarm collection, alarm reporting, visual alarms and alarm audible functions.