A system is disclosed, including a plurality of access units, a plurality of circuit nodes each coupled to a respective access unit, and a plurality of data processing nodes each coupled to a respective access unit. A particular data processing node may be configured to generate a plurality of data transactions. The particular data processing node may also be configured to determine an availability of a coupled access unit. In response to a determination that the coupled access unit is unavailable, the particular data processing node may be configured to halt a transfer of the plurality of data transactions to the coupled access unit and assert a halt indicator signal. In response to a determination that the coupled access unit is available, the particular data processing node may be configured to transfer the particular data transaction to the coupled access unit.