+/* NXAST_MULTIPATH: Multipath link choice algorithm to apply.
+ *
+ * In the descriptions below, 'n_links' is max_link + 1. */
+enum nx_mp_algorithm {
+ /* link = hash(flow) % n_links.
+ *
+ * Redistributes all traffic when n_links changes. O(1) performance. See
+ * RFC 2992.
+ *
+ * Use UINT16_MAX for max_link to get a raw hash value. */
+ NX_MP_ALG_MODULO_N,
+
+ /* link = hash(flow) / (MAX_HASH / n_links).
+ *
+ * Redistributes between one-quarter and one-half of traffic when n_links
+ * changes. O(1) performance. See RFC 2992.
+ */
+ NX_MP_ALG_HASH_THRESHOLD,
+
+ /* for i in [0,n_links):
+ * weights[i] = hash(flow, i)
+ * link = { i such that weights[i] >= weights[j] for all j != i }
+ *
+ * Redistributes 1/n_links of traffic when n_links changes. O(n_links)
+ * performance. If n_links is greater than a threshold (currently 64, but
+ * subject to change), Open vSwitch will substitute another algorithm
+ * automatically. See RFC 2992. */
+ NX_MP_ALG_HRW, /* Highest Random Weight. */
+
+ /* i = 0
+ * repeat:
+ * i = i + 1
+ * link = hash(flow, i) % arg
+ * while link > max_link
+ *
+ * Redistributes 1/n_links of traffic when n_links changes. O(1)
+ * performance when arg/max_link is bounded by a constant.
+ *
+ * Redistributes all traffic when arg changes.
+ *
+ * arg must be greater than max_link and for best performance should be no
+ * more than approximately max_link * 2. If arg is outside the acceptable
+ * range, Open vSwitch will automatically substitute the least power of 2
+ * greater than max_link.
+ *
+ * This algorithm is specific to Open vSwitch.
+ */
+ NX_MP_ALG_ITER_HASH /* Iterative Hash. */
+};
+\f
+/* Action structure for NXAST_AUTOPATH.
+ *
+ * This action performs the following steps in sequence:
+ *
+ * 1. Hashes the flow using an implementation-defined hash function.
+ *
+ * The hashed fields' values are drawn from the current state of the
+ * flow, including all modifications that have been made by actions up to
+ * this point.
+ *
+ * 2. Selects an OpenFlow 'port'.
+ *
+ * 'port' is selected in an implementation-defined manner, taking into
+ * account 'id' and the hash value calculated in step 1.
+ *
+ * Generally a switch will have been configured with a set of ports that
+ * may be chosen given 'id'. The switch may take into account any number
+ * of factors when choosing 'port' from its configured set. Factors may
+ * include carrier, load, and the results of configuration protocols such
+ * as LACP.
+ *
+ * 3. Stores 'port' in dst[ofs:ofs+n_bits].
+ *
+ * The format and semantics of 'dst' and 'ofs_nbits' are similar to those
+ * for the NXAST_REG_LOAD action, except that 'dst' must be
+ * NXM_NX_REG(idx) for 'idx' in the switch's supported range.
+ *
+ * The switch will reject actions in which ofs+n_bits is greater than the width
+ * of 'dst', with error type OFPET_BAD_ACTION, code OFPBAC_BAD_ARGUMENT.
+ */
+struct nx_action_autopath {
+ ovs_be16 type; /* OFPAT_VENDOR. */
+ ovs_be16 len; /* Length is 20. */
+ ovs_be32 vendor; /* NX_VENDOR_ID. */
+ ovs_be16 subtype; /* NXAST_MULTIPATH. */
+
+ /* Where to store the result. */
+ ovs_be16 ofs_nbits; /* (ofs << 6) | (n_bits - 1). */
+ ovs_be32 dst; /* Destination register. */
+
+ ovs_be32 id; /* Autopath ID. */
+ ovs_be32 pad;
+};
+OFP_ASSERT(sizeof(struct nx_action_autopath) == 24);