1 Proposal for Group Selection Method Property
4 Author: Simon Horman <simon.horman@netronome.com>, et al.
5 Initial Public Revision: September 2014
14 4. Experimenter Messages
21 This text describes a Netronome Extension to OpenFlow 1.5 that allows a
22 controller to provide more information on the selection method for select
23 groups. This proposal is in the form of an enhanced select group type.
25 This may subsequently be proposed as an extension or update to
26 the OpenFlow specification.
32 A new Netronome group experimenter property is defined which provides
33 compatibility with the group mod message defined in Open Flow 1.5
34 (also known as ONF EXT-350) and allows parameters for the selection
35 method of select groups to be passed by the controller. In particular it
36 allows controllers to:
38 * Specify the fields used for bucket selection by the select group.
40 * Designate the selection method used.
42 * Provide a non-field parameter to the selection method.
48 The Experimenter ID of this extension is:
50 NTR_VENDOR_ID = 0x0000154d
53 4. Group Experimenter Property
54 ==============================
56 The following group property experimenter type defined by this extension.
58 enum ntr_group_mod_subtype {
59 NTRT_SELECTION_METHOD = 1,
63 Modifications to the group table from the controller may be done with
64 a OFPT_GROUP_MOD message described Open Flow 1.5. Group Entry
65 Message. Of relevance here is that Open Flow 1.5 group messages have
68 This proposal is defined in terms of an implementation of struct
69 ofp_group_prop_experimenter which is described in Open Flow 1.5. The
72 struct ntr_group_prop_selection_method {
73 ovs_be16 type; /* OFPGPT_EXPERIMENTER. */
74 ovs_be16 length; /* Length in bytes of this property. */
75 ovs_be32 experimenter; /* NTR_VENDOR_ID. */
76 ovs_be32 exp_type; /* NTRT_SELECTION_METHOD. */
78 char selection_method[NTR_MAX_SELECTION_METHOD_LEN];
80 ovs_be64 selection_method_param; /* Non-Field parameter for
81 * bucket selection. */
84 * - Exactly (length - 40) (possibly 0) bytes containing OXM TLVs, then
85 * - Exactly ((length + 7)/8*8 - length) (between 0 and 7) bytes of
87 * In summary, ntr_group_prop_selection_method is padded as needed,
88 * to make its overall size a multiple of 8, to preserve alignment
89 * in structures using it.
91 /* uint8_t field_array[0]; */ /* Zero or more fields encoded as
92 * OXM TLVs where the has_mask bit must
93 * be zero and the value it specifies is
94 * a mask to apply to packet fields and
95 * then input them to the selection
96 * method of a select group. */
97 /* uint8_t pad2[0]; */
99 OFP_ASSERT(sizeof(struct ntr_group_mod) == 40);
102 This property may only be used with group mod messages whose:
103 * command is OFPGC_ADD or OFPGC_MODIFY; and
104 * type is OFPGT_SELECT
107 The type field is the OFPGPT_EXPERIMENTER which is
108 defined in EXT-350 as 0xffff.
111 The experimenter field is the Experimenter ID (see 3).
114 The exp_type field is NTRT_SELECTION_METHOD.
117 The group selection_method is a null-terminated string which if non-zero
118 length specifies a selection method known to an underlying layer of the
119 switch. The value of NTR_MAX_SELECTION_METHOD_LEN is 16.
121 The group selection_method may be zero-length to request compatibility with
125 The selection_method_param provides a non-field parameter for
126 the group selection_method. It must be all-zeros unless the
127 group selection_method is non-zero length.
129 The selection_method_param may for example be used as an initial value for
130 the hash of a hash group selection method.
133 The fields field is an ofp_match structure which includes the fields which
134 should be used as inputs to bucket selection. ofp_match is described in
135 Open Flow 1.4 section 7.2.2 Flow Match Structures.
137 Fields must not be specified unless the group selection_method is non-zero
140 The pre-requisites for fields specified must be satisfied in the match for
141 any flow that uses the group.
143 Masking is allowed but not required for fields whose TLVs allow masking.
145 The fields may for example be used as the fields that are hashed
146 by a hash group selection method.
152 This proposal has been developed independently of any similar work in this
153 area. No such work is known.