You are using a deprecated Browser. Internet Explorer is no longer supported by Xilinx.
LogiCORE IP Ethernet AVB Endpoint v3.1 - Timing errors are occasionally seen when targeting Spartan-3 devices
When I use the Ethernet AVB Endpoint v3.1 core and target a Spartan-3 device, the following timing constraint occasionally produces timing errors similar to the following:
TS_rtc_clock = PERIOD TIMEGRP "rtc_clock" 8 ns HIGH 50%;
Running the implement tools again with a different cost table usually resolves this issue.