32.6.13 Wake on LAN Support

The receive block supports Wake on LAN by detecting the following events on incoming receive frames:

  • Magic packet
  • Address Resolution Protocol (ARP) request to the device IP address
  • Specific address 1 filter match
  • Multicast hash filter match

These events can be individually enabled through bits [19:16] of the Wake on LAN register. Also, for Wake on LAN detection to occur, receive enable must be set in the Network Control register, however a receive buffer does not have to be available.

In case of an ARP request, specific address 1 or multicast filter events will occur even if the frame is errored. For magic packet events, the frame must be correctly formed and error free.

A magic packet event is detected if all of the following are true:

  • Magic packet events are enabled through bit 16 of the Wake on LAN register
  • The frame's destination address matches specific address 1
  • The frame is correctly formed with no errors
  • The frame contains at least 6 bytes of 0xFF for synchronization
  • There are 16 repetitions of the contents of Specific Address 1 register immediately following the synchronization

An ARP request event is detected if all of the following are true:

  • ARP request events are enabled through bit 17 of the Wake on LAN register
  • Broadcasts are allowed by bit 5 in the Network Configuration register
  • The frame has a broadcast destination address (bytes 1 to 6)
  • The frame has a type ID field of 0x0806 (bytes 13 and 14)
  • The frame has an ARP operation field of 0x0001 (bytes 21 and 22)
  • The least significant 16 bits of the frame's ARP target protocol address (bytes 41 and 42) match the value programmed in bits[15:0] of the Wake on LAN register

The decoding of the ARP fields adjusts automatically if a VLAN tag is detected within the frame. The reserved value of 0x0000 for the Wake on LAN target address value will not cause an ARP request event, even if matched by the frame.

A specific address 1 filter match event will occur if all of the following are true:

  • Specific address 1 events are enabled through bit 18 of the Wake on LAN register
  • The frame's destination address matches the value programmed in the Specific Address 1 registers

A multicast filter match event will occur if all of the following are true:

  • Multicast hash events are enabled through bit 19 of the Wake on LAN register
  • Multicast hash filtering is enabled through bit 6 of the Network Configuration register
  • The frame destination address matches against the multicast hash filter
  • The frame destination address is not a broadcast