--- /dev/null
+#ifndef _LLH_H
+#define _LLH_H
+
+/** @file
+ *
+ * Link-layer headers
+ *
+ * This file defines a media-independent link-layer header, used for
+ * communication between the network and link layers of the stack.
+ *
+ */
+
+#include <stdint.h>
+
+/** Maximum length of a link-layer address */
+#define MAX_LLH_ADDR_LEN 6
+
+/** Maximum length of a network-layer address */
+#define MAX_NET_ADDR_LEN 4
+
+/** A media-independent link-layer header
+ *
+ * This structure represents a generic link-layer header. It never
+ * appears on the wire, but is used to communicate between different
+ * layers within the gPXE protocol stack.
+ */
+struct gpxehdr {
+ /** The network-layer protocol
+ *
+ * This is the network-layer protocol expressed as an
+ * ETH_P_XXX constant, in network-byte order.
+ */
+ uint16_t net_proto;
+ /** Broadcast flag
+ *
+ * Filled in only on outgoing packets.
+ */
+ int broadcast : 1;
+ /** Multicast flag
+ *
+ * Filled in only on outgoing packets.
+ */
+ int multicast : 1;
+ /** Network-layer address length
+ *
+ * Filled in only on outgoing packets.
+ */
+ uint8_t net_addr_len;
+ /** Network-layer address
+ *
+ * Filled in only on outgoing packets.
+ */
+ uint8_t net_addr[MAX_NET_ADDR_LEN];
+} __attribute__ (( packed ));
+
+#endif /* _LLH_H */