I have noticed there are references and links to the Application Note "10-Gigabit Media Independent Interface (XGMII) Reference Design" (XAPP606), but I cannot find this document anywhere and the links are not functional. Is this Application Note still available, and where can I find it? Where can I get a reference design for XGMII?
XAPP606 is no longer offered on the Xilinx Web site, and there are currently no plans to re-issue it publicly.
When the 10-Gigabit Ethernet MAC Core was released back in 2001, the original implementation of the XGMII was as per XAPP606. The XGMII design is now provided with the 10-Gig MAC Core in CORE Generator. The design in CORE Generator contains necessary updates for Virtex-II and later devices. This includes not disabling Duty Cycle Correction for Virtex-II DCMs (as was done in XAPP606).
The XGMII design in the 10-Gig MAC is available from CORE Generator. Without having a license, customers can generate simulation models for this core. With these models you get an "example design" that implements an XGMII, available in either VHDL or Verilog.