-- binary
04 13 # version, type
00 80 # length
12 34 56 78 # xid
00 07 # stats_type
00 00 # flags
00 00 00 00 # pad
00 68 # entries[0].length
03 # entries[0].group_type
00 # entries[0].pad
00 00 00 01 # entries[0].group_id
00 30 # entries[0].buckets[0].len
00 01 # entries[0].buckets[0].weight
00 00 00 05 # entries[0].buckets[0].watch_port
ff ff ff ff # entries[0].buckets[0].watch_group
00 00 00 00 # entries[0].pad
00 00 # entries[0].buckets[0].actions[0].type
00 10 # entries[0].buckets[0].actions[0].len
00 00 00 05 # entries[0].buckets[0].actions[0].port
00 00 # entries[0].buckets[0].actions[0].max_len
00 00 00 00 00 00 # entries[0].pad
00 00 # entries[0].buckets[0].actions[1].type
00 10 # entries[0].buckets[0].actions[1].len
00 00 00 06 # entries[0].buckets[0].actions[1].port
00 00 # entries[0].buckets[0].actions[1].max_len
00 00 00 00 00 00 # entries[0].pad
00 30 # entries[0].buckets[1].len
00 01 # entries[0].buckets[1].weight
00 00 00 06 # entries[0].buckets[1].watch_port
ff ff ff ff # entries[0].buckets[1].watch_group
00 00 00 00 # entries[0].pad
00 00 # entries[0].buckets[1].actions[0].type
00 10 # entries[0].buckets[1].actions[0].len
00 00 00 05 # entries[0].buckets[1].actions[0].port
00 00 # entries[0].buckets[1].actions[0].max_len
00 00 00 00 00 00 # entries[0].pad
00 00 # entries[0].buckets[1].actions[1].type
00 10 # entries[0].buckets[1].actions[1].len
00 00 00 06 # entries[0].buckets[1].actions[1].port
00 00 # entries[0].buckets[1].actions[1].max_len
00 00 00 00 00 00 # entries[0].pad
00 08 # entries[1].length
03 # entries[1].group_type
00 # entries[1].pad
00 00 00 02 # entries[1].group_id
-- python
ofp.message.group_desc_stats_reply(
    xid=0x12345678,
    flags=0,
    entries=[
        ofp.group_desc_stats_entry(
            group_type=ofp.OFPGT_FF,
            group_id=1,
            buckets=[
                ofp.bucket(
                    weight=1,
                    watch_port=5,
                    watch_group=0xffffffff,
                    actions=[
                        ofp.action.output(port=5, max_len=0),
                        ofp.action.output(port=6, max_len=0)]),
                ofp.bucket(
                    weight=1,
                    watch_port=6,
                    watch_group=0xffffffff,
                    actions=[
                        ofp.action.output(port=5, max_len=0),
                        ofp.action.output(port=6, max_len=0)])]),
        ofp.group_desc_stats_entry(group_type=ofp.OFPGT_FF, group_id=2, buckets=[])])