openflow: Table maintenance commands for Geneve options.

In order to work with Geneve options, we need to maintain a mapping
table between an option (defined by <class, type, length>) and
an NXM field that can be operated on for the purposes of matches,
actions, etc. This mapping must be explicitly specified by the
user.

Conceptually, this table could be communicated using either OpenFlow
or OVSDB. Using OVSDB requires less code and definition of extensions
than OpenFlow but introduces the possibility that mapping table
updates and flow modifications are desynchronized from each other.
This is dangerous because the mapping table signifcantly impacts the
way that flows using Geneve options are installed and processed by
OVS. Therefore, the mapping table is maintained using OpenFlow commands
instead, which opens the possibility of using synchronization between
table changes and flow modifications through barriers, bundles, etc.

There are two primary groups of OpenFlow messages that are introduced
as Nicira extensions: modification commands (add, delete, clear mappings)
and table status request/reply to dump the current table along with switch
information.

Note that mappings should not be changed while they are in active use by
a flow. The result of doing so is undefined.

This only adds the OpenFlow infrastructure but doesn't actually
do anything with the information yet after the messages have been
decoded.

Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/utilities/ovs-ofctl.8.in b/utilities/ovs-ofctl.8.in
index 63c2ecca8..ead38e700 100644
--- a/utilities/ovs-ofctl.8.in
+++ b/utilities/ovs-ofctl.8.in
@@ -407,6 +407,43 @@ Remove buckets to an existing group present in the \fIswitch\fR's group table.
 If no \fIcommand_bucket_id\fR is present in the group specification then all
 buckets of the group are removed.
 .
+.SS "OpenFlow Switch Geneve Option Table Commands"
+.
+In order to work with Geneve options, it is necessary to maintain a mapping
+table between an option (defined by <class, type, length>) and an NXM field
+that can be operated on for the purposes of matches, actions, etc. This
+mapping must be explicitly specified by the user through the following
+commands. The format for \fIoptions\fR is given in \fBOption Syntax\fR below.
+
+Note that a given mapping should not be changed while it is in active use by
+a flow. The result of doing so is undefined.
+
+These commands are Nicira extensions to OpenFlow and require Open vSwitch
+2.5 or later.
+
+.IP "\fBadd\-geneve\-map \fIswitch options\fR"
+Add each option entry to \fIswitch\fR's tables. Duplicate fields are
+rejected.
+.
+.IP "\fBdel\-geneve\-map \fIswitch \fR[\fIoptions\fR]"
+Delete each option entry in \fIswitch\fR's tables based on its field index.
+Fields that aren't already mapped will be ignored. If no options are
+specified then the entire table will be cleared.
+.
+.IP "\fBdump\-geneve\-map \fIswitch\fR"
+Show the currently mapped fields in the switch's option table as well
+as switch capabilities.
+.
+.IP "\fBOption Syntax\fR"
+\fB{class=\fIclass\fB,type=\fItype\fB,len=\fIlength\fB}->tun_metadata\fIn\fR
+
+An option can be specified in this form (repeating as necessary and
+separated by commas). For example, the follow is used to map a new option:
+
+.RS
+add-geneve-map br0 "{class=0xffff,type=0,len=4}->tun_metadata0"
+.RE
+.
 .SS "OpenFlow Switch Monitoring Commands"
 .
 .IP "\fBsnoop \fIswitch\fR"