The address swap module is configured for use
on the loopback path. This permits the example design, when targeted to a suitable board, to
be connected to an Ethernet protocol tester. The address swap module waits until both the DA
and SA are received before starting to send data on to the TX FIFO.
If enabled, the address swap module swaps the destination and
source addresses of each frame as shown in the following figure to ensure that the outgoing
frame destination address matches the source address of the link partner. If not enabled, the
DA and SA are left untouched. The address swap module transmits the frame control signals with
an equal latency to the frame data.
Figure 1. Modification of Frame Data by Address Swap Module