  During the next major shutdown (2019-2020), the ATLAS experiment at the LHC
will adopt the Front-End Link eXchange (FELIX) system as the interface between
the data acquisition, detector control and TTC (Timing, Trigger and Control)
systems and new or updated trigger and detector front-end electronics. FELIX
will function as a router between custom serial links from front-end ASICs and
FPGAs to data collection and processing components via a commodity switched
network. Links may aggregate many slower links or be a single high bandwidth
link. FELIX will also forward the LHC bunch-crossing clock, fixed latency
trigger accepts and resets received from the TTC system to front-end
electronics. The FELIX system uses commodity server technology in combination
with FPGA-based PCIe I/O cards. The FELIX servers will run a software routing
platform serving data to network clients. Commodity servers connected to FELIX
systems via the same network will run the new Software Readout Driver (SW ROD)
infrastructure for event fragment building and buffering, with support for
detector or trigger specific data processing, and will serve the data upon
request to the ATLAS High Level Trigger for Event Building and Selection. This
paper will cover the design and status of FELIX, the SW ROD, results of early
performance testing and integration tests with several ATLAS front-ends.
