When preparing to build ECMP and static route flows, routes are sorted
into unique routes (meaning they are not part of a group) or they are
added to EMCP groups. Then, ECMP route flows are built out of the
groups, and static route flows are built out of the unique routes.
However, 'unique routes' include ones that use the
--ecmp-symmetric-reply flag, meaning that they may not be added to an
ECMP group, and thus ECMP symmetric reply would not be used for those
flows.
For example, if one route is added and traffic is started, and then
later another route is added, the already flowing traffic might be
rerouted since it wasn't conntracked initially. This could break
symmetric reply with traffic using a different next-hop than before.
This change makes it so that when the --ecmp-symmetric-reply flag is
used, even for unique routes, an ECMP group is created which they are
added to. Thus they are added to the ECMP route flow, rather than
static. This allows ECMP groups to persist even when there is only one
route.
Edited documentation to support this change.
Also updated incorrect actions in documentation.
Fixes: 4fdca656857d ("Add ECMP symmetric replies.")
Reported-at: https://issues.redhat.com/browse/FDP-786
Signed-off-by: Rosemarie O'Riorden <[email protected]>
---
northd/northd.c | 33 ++++++++++++++++++++++-----------
northd/ovn-northd.8.xml | 13 ++++++++++++-
tests/ovn-northd.at | 5 ++++-
3 files changed, 38 insertions(+), 13 deletions(-)
diff --git a/northd/northd.c b/northd/northd.c
index 983c464eb..8ae3a75bd 100644
--- a/northd/northd.c
+++ b/northd/northd.c
@@ -11567,21 +11567,27 @@ build_ecmp_route_flow(struct lflow_table *lflows,
struct ovn_datapath *od,
struct ds actions = DS_EMPTY_INITIALIZER;
ds_put_format(&actions, "ip.ttl--; flags.loopback = 1; %s = %"PRIu16
- "; %s = select(", REG_ECMP_GROUP_ID, eg->id,
- REG_ECMP_MEMBER_ID);
+ "; %s = ", REG_ECMP_GROUP_ID, eg->id, REG_ECMP_MEMBER_ID);
- bool is_first = true;
- LIST_FOR_EACH (er, list_node, &eg->route_list) {
- if (is_first) {
- is_first = false;
- } else {
- ds_put_cstr(&actions, ", ");
+ if (!ovs_list_is_singleton(&eg->route_list)) {
+ bool is_first = true;
+
+ ds_put_cstr(&actions, "select(");
+ LIST_FOR_EACH (er, list_node, &eg->route_list) {
+ if (is_first) {
+ is_first = false;
+ } else {
+ ds_put_cstr(&actions, ", ");
+ }
+ ds_put_format(&actions, "%"PRIu16, er->id);
}
- ds_put_format(&actions, "%"PRIu16, er->id);
+ ds_put_cstr(&actions, ");");
+ } else {
+ er = CONTAINER_OF(ovs_list_front(&eg->route_list),
+ struct ecmp_route_list_node, list_node);
+ ds_put_format(&actions, "%"PRIu16"; next;", er->id);
}
- ds_put_cstr(&actions, ");");
-
ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_ROUTING, priority,
ds_cstr(&route_match), ds_cstr(&actions),
lflow_ref);
@@ -13543,6 +13549,11 @@ build_static_route_flows_for_lrouter(
if (group) {
ecmp_groups_add_route(group, route);
}
+ } else if (route->ecmp_symmetric_reply) {
+ /* Traffic for symmetric reply routes has to be conntracked
+ * even if there is only one next-hop, in case another next-hop
+ * is added later. */
+ ecmp_groups_add(&ecmp_groups, route);
} else {
unique_routes_add(&unique_routes, route);
}
diff --git a/northd/ovn-northd.8.xml b/northd/ovn-northd.8.xml
index ede38882a..ef5cd0c8c 100644
--- a/northd/ovn-northd.8.xml
+++ b/northd/ovn-northd.8.xml
@@ -4328,7 +4328,18 @@ next;
ip.ttl--;
flags.loopback = 1;
reg8[0..15] = <var>GID</var>;
-select(reg8[16..31], <var>MID1</var>, <var>MID2</var>, ...);
+reg8[16..31] = select(<var>MID1</var>, <var>MID2</var>, ...);
+ </pre>
+ <p>
+ However, when there is only one route in an ECMP group, group actions
+ will be:
+ </p>
+
+ <pre>
+ip.ttl--;
+flags.loopback = 1;
+reg8[0..15] = <var>GID</var>;
+reg8[16..31] = <var>MID1</var>);
</pre>
</li>
diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
index dcc3dbbc3..d459c23c0 100644
--- a/tests/ovn-northd.at
+++ b/tests/ovn-northd.at
@@ -6799,20 +6799,23 @@ check ovn-nbctl lsp-set-type public-lr0 router
check ovn-nbctl lsp-set-addresses public-lr0 router
check ovn-nbctl lsp-set-options public-lr0 router-port=lr0-public
+# ECMP flows will be added even if there is only one next-hop.
check ovn-nbctl --wait=sb --ecmp-symmetric-reply lr-route-add lr0 1.0.0.1
192.168.0.10
ovn-sbctl dump-flows lr0 > lr0flows
AT_CHECK([grep -w "lr_in_ip_routing" lr0flows | ovn_strip_lflows], [0], [dnl
table=??(lr_in_ip_routing ), priority=0 , match=(1), action=(drop;)
+ table=??(lr_in_ip_routing ), priority=10300,
match=(ct_mark.ecmp_reply_port == 1 && reg7 == 0 && ip4.dst == 1.0.0.1/32),
action=(ip.ttl--; flags.loopback = 1; eth.src = 00:00:20:20:12:13; reg1 =
192.168.0.1; outport = "lr0-public"; next;)
table=??(lr_in_ip_routing ), priority=10550, match=(nd_rs || nd_ra),
action=(drop;)
table=??(lr_in_ip_routing ), priority=194 , match=(inport == "lr0-public"
&& ip6.dst == fe80::/64), action=(ip.ttl--; reg8[[0..15]] = 0; xxreg0 =
ip6.dst; xxreg1 = fe80::200:20ff:fe20:1213; eth.src = 00:00:20:20:12:13;
outport = "lr0-public"; flags.loopback = 1; next;)
table=??(lr_in_ip_routing ), priority=74 , match=(ip4.dst ==
192.168.0.0/24), action=(ip.ttl--; reg8[[0..15]] = 0; reg0 = ip4.dst; reg1 =
192.168.0.1; eth.src = 00:00:20:20:12:13; outport = "lr0-public";
flags.loopback = 1; next;)
- table=??(lr_in_ip_routing ), priority=97 , match=(reg7 == 0 && ip4.dst
== 1.0.0.1/32), action=(ip.ttl--; reg8[[0..15]] = 0; reg0 = 192.168.0.10; reg1
= 192.168.0.1; eth.src = 00:00:20:20:12:13; outport = "lr0-public";
flags.loopback = 1; next;)
+ table=??(lr_in_ip_routing ), priority=97 , match=(reg7 == 0 && ip4.dst
== 1.0.0.1/32), action=(ip.ttl--; flags.loopback = 1; reg8[[0..15]] = 1;
reg8[[16..31]] = 1; next;)
])
AT_CHECK([grep -e "lr_in_ip_routing_ecmp" lr0flows | ovn_strip_lflows], [0],
[dnl
table=??(lr_in_ip_routing_ecmp), priority=0 , match=(1), action=(drop;)
+ table=??(lr_in_ip_routing_ecmp), priority=100 , match=(reg8[[0..15]] == 1
&& reg8[[16..31]] == 1), action=(reg0 = 192.168.0.10; reg1 = 192.168.0.1;
eth.src = 00:00:20:20:12:13; outport = "lr0-public"; next;)
table=??(lr_in_ip_routing_ecmp), priority=150 , match=(reg8[[0..15]] == 0),
action=(next;)
])
--
2.46.0
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