diff --git a/libknet/libknet.h b/libknet/libknet.h
index a06aeeb1..53466a04 100644
--- a/libknet/libknet.h
+++ b/libknet/libknet.h
@@ -1,126 +1,136 @@
 #ifndef __RING_H__
 #define __RING_H__
 
 #include <stdint.h>
 #include <netinet/in.h>
 
 typedef struct knet_handle *knet_handle_t;
 
 #define KNET_RING_DEFPORT 50000
 #define KNET_RING_RCVBUFF 8388608
 
 #define KNET_MAX_HOST 65536
 #define KNET_MAX_LINK 8
 #define KNET_MAX_HOST_LEN 64
 
 struct knet_link {
 	uint8_t link_id;
 	int sock;
 	char ipaddr[KNET_MAX_HOST_LEN];
 	char port[6];
 	struct sockaddr_storage address;
 	unsigned int ready:1; /* link is configured and ready to be used */
 	unsigned int enabled:1;	/* link is enabled for data */
 	unsigned long long latency; /* average latency computed by fix/exp */
 	unsigned int latency_exp;
 	unsigned int latency_fix;
 	unsigned long long ping_interval;
 	unsigned long long pong_timeout;
 	struct timespec ping_last;
 	struct timespec pong_last;
 };
 
 struct knet_host {
 	uint16_t node_id;
 	char name[KNET_MAX_HOST_LEN];
 	unsigned int active:1; /* data packets are sent to all links */
 	struct knet_listener *listener;
 	struct knet_link link[KNET_MAX_LINK];
 	struct knet_host *next;
 };
 
 struct knet_listener {
 	int sock;
 	char ipaddr[KNET_MAX_HOST_LEN];
 	char port[6];
 	struct sockaddr_storage address;
 	struct knet_listener *next;
 };
 
+/* change those to uint8 and UINT8_MAX to test rollover */
+/*
+typedef uint32_t seq_num_t;
+#define SEQ_MAX UINT32_MAX
+*/
+typedef uint16_t seq_num_t;
+#define SEQ_MAX UINT16_MAX
+
 union knet_frame_data {
-	uint8_t			kfd_data[0];
 	struct {
-		uint16_t	kfd_node;
+		seq_num_t	kfd_seq_num;
+		uint8_t		kfd_data[0];
+	} data;
+	struct {
 		uint8_t		kfd_link;
 		struct timespec	kfd_time;
-	};
+	} ping;
 } __attribute__((packed));
 
 struct knet_frame {
 	uint32_t 		kf_magic;
 	uint8_t			kf_version;
 	uint8_t			kf_type;
-	uint16_t		__pad;
+	uint16_t		kf_node;
 	union knet_frame_data	kf_payload;
 } __attribute__((packed));
 
-#define kf_data kf_payload.kfd_data
-#define kf_node kf_payload.kfd_node
-#define kf_link kf_payload.kfd_link
-#define kf_time kf_payload.kfd_time
+#define kf_seq_num kf_payload.data.kfd_seq_num
+#define kf_data kf_payload.data.kfd_data
+#define kf_link kf_payload.ping.kfd_link
+#define kf_time kf_payload.ping.kfd_time
 
 #define KNET_FRAME_SIZE (sizeof(struct knet_frame) - sizeof(union knet_frame_data))
 
 #define KNET_FRAME_MAGIC 0x12344321
 #define KNET_FRAME_VERSION 0x01
 
 #define KNET_FRAME_DATA 0x00
 #define KNET_FRAME_PING 0x81
 #define KNET_FRAME_PONG 0x82
 #define KNET_FRAME_PMSK 0x80 /* ping/pong packet mask */
 
 #define KNET_MIN_KEY_LEN 1024
 #define KNET_MAX_KEY_LEN 4096
 
 struct knet_handle_cfg {
 	int		fd;
 	uint16_t	node_id;
 	char		*crypto_cipher_type;
 	char		*crypto_hash_type;
 	unsigned char	*private_key;
 	unsigned int	private_key_len;
 	off_t		dst_nodeid_offset; /* destination node_id offset in data packet */
 	size_t		dst_nodeid_len; /* 0 = broadcast to all, 1|2 256/64k nodes, > 2 == 2 */
 };
 
 knet_handle_t knet_handle_new(const struct knet_handle_cfg *knet_handle_cfg);
 void knet_handle_setfwd(knet_handle_t knet_h, int enabled);
 int knet_handle_free(knet_handle_t knet_h);
 
 int knet_host_add(knet_handle_t knet_h, uint16_t node_id);
 int knet_host_acquire(knet_handle_t knet_h, struct knet_host **host);
 int knet_host_get(knet_handle_t knet_h, uint16_t node_id, struct knet_host **host);
 int knet_host_release(knet_handle_t knet_h, struct knet_host **host);
 int knet_host_remove(knet_handle_t knet_h, uint16_t node_id);
 
 void knet_link_timeout(struct knet_link *lnk, time_t interval, time_t timeout, int precision);
 
 #define KNET_HOST_FOREACH_NEXT 0	/* next host */
 #define KNET_HOST_FOREACH_FOUND 1	/* host found, exit loop */
 
 struct knet_host_search {
 	int 			param1;	/* user parameter 1 */
 	void 			*data1;	/* user data pointer 1 */
 	void 			*data2;	/* user data pointer 2 */
 	int 			retval;	/* search return value */
 };
 
 typedef int (*knet_link_fn_t)(knet_handle_t knet_h, struct knet_host *host, struct knet_host_search *data);
 int knet_host_foreach(knet_handle_t knet_h, knet_link_fn_t linkfun, struct knet_host_search *data);
 
 int knet_listener_acquire(knet_handle_t knet_h, struct knet_listener **head, int writelock);
 int knet_listener_release(knet_handle_t knet_h);
 int knet_listener_add(knet_handle_t knet_h, struct knet_listener *listener);
 int knet_listener_remove(knet_handle_t knet_h, struct knet_listener *listener);
 
 #endif