Considering two logical datapaths (DP1 and DP2) and a logical flow that
is shared between the two, ovn-northd will create the following SB
records:
Datapaths: DP1, DP2
Datapath_Group: DPG1 {dps=[DP1, DP2]}
Logical_Flow: LF {dp_group=DPG1}
If an ovn-controller is conditionally monitoring DP1 and DP2 its
monitor conditions look like this:
Datapath_Group table when:
- Datapath_Group.datapaths in {DP1._uuid, DP2._uuid}
Logical_Flow table when:
- Logical_Flow.logical_datapath in {DP1._uuid, DP2._uuid}
- Logical_Flow.logical_dp_group in {DPG1._uuid}
If at this point a new logical datapath DP3 is created (e.g., a LS is
added) and the logical flow LF is shared with this third datapath, then
ovn-northd populates the SB with the following contents, replacing
old DPG1 with DPG1-new:
Datapaths: DP1, DP2, DP3
Datapath_Group: DPG1-new {dps=[DP1, DP2, DP3]}
Logical_Flow: LF {dp_group=DPG1-new}
At this point, the SB ovsdb-server will send the following updates to
ovn-controller, to match the current monitor condition it requested:
Datapaths:
- "insert" DP3
Datapath_Group:
- "delete" DPG1
- "insert" DPG1-new {dps=[DP1, DP2, DP3]}
Logical_Flow:
- "delete" LF
The logical flow is deleted from the client's view of the database
because the monitor condition for Logical_Flow records doesn't include
DPG1-new._uuid.
Now ovn-controller will:
- delete all openflows corresponding to LF, including the ones generated
for datapaths DP1 and DP2.
- compute new set of monitor conditions and send the monitor_cond_change
request to the SB:
Datapath_Group table when Datapath_Group.uuid in {DPG1-new._uuid}
Logical_Flow table when:
- Logical_Flow.logical_datapath in {DP1._uuid, DP2._uuid, DP3._uuid}
- Logical_Flow.logical_dp_group in {DPG1-new._uuid}
Upon processing this new set of conditions, the SB sends the following
update:
Logical_Flow:
- "insert" LF <--- now LF.logical_dp_group matches the condition.
Finally, ovn-controller will add all openflows that correspond to LF, on
all datapaths, DP1, DP2, DP3.
There is therefore a window in which traffic on DP1 and DP2 might be
dropped because openflows corresponding to LF1 on DP1 and DP2 have been
removed but not yet reinstalled.
To avoid this we now unconditionally monitor all logical flows that
refer to datapath groups.
Fixes: 4b946b366c4c ("controller: Add support for Logical Datapath Groups.")
Reported-at: https://bugzilla.redhat.com/1947056
Suggested-by: Ilya Maximets <[email protected]>
Signed-off-by: Dumitru Ceara <[email protected]>
---
controller/ovn-controller.c | 26 +++++++++-----------------
1 file changed, 9 insertions(+), 17 deletions(-)
diff --git a/controller/ovn-controller.c b/controller/ovn-controller.c
index 16c8ecb21..6f7c9ea61 100644
--- a/controller/ovn-controller.c
+++ b/controller/ovn-controller.c
@@ -259,23 +259,15 @@ update_sb_monitors(struct ovsdb_idl *ovnsb_idl,
uuid);
}
- /* Updating conditions to receive logical flows that references
- * datapath groups containing local datapaths. */
- const struct sbrec_logical_dp_group *group;
- SBREC_LOGICAL_DP_GROUP_FOR_EACH (group, ovnsb_idl) {
- struct uuid *uuid = CONST_CAST(struct uuid *,
- &group->header_.uuid);
- size_t i;
-
- for (i = 0; i < group->n_datapaths; i++) {
- if (get_local_datapath(local_datapaths,
- group->datapaths[i]->tunnel_key)) {
- sbrec_logical_flow_add_clause_logical_dp_group(
- &lf, OVSDB_F_EQ, uuid);
- break;
- }
- }
- }
+ /* Datapath groups are immutable, which means a new group record is
+ * created when a datapath is added to a group. The logical flows
+ * referencing a datapath group are also updated in such cases but the
+ * new group UUID is not known by ovn-controller until the SB update
+ * is received. To avoid unnecessarily removing and adding lflows
+ * that reference datapath groups, set the monitor condition to always
+ * request all of them.
+ */
+ sbrec_logical_flow_add_clause_logical_dp_group(&lf, OVSDB_F_NE, NULL);
}
out:;
--
2.27.0
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