Option to forward BPDU (Ethernet control class) frames

Currently, a NORMAL action bridge drops reserved-multicast-mac addresses;
01-80-c2-00-00-[f0:ff]. A node that does not implement STP should have an
option to forward such frames.

This commit proposes to have a configuration option to allow forwarding of
BPDU class frames.  To ensure backward compatibility, this option is
disabled by default.

This config can be set using bridge's other-config column, for e.g
ovs-vsctl set bridge br0 other-config:forward-bpdu=true

Changing this option can revalidate all flows in a software-OVS
implementation (ofproto-dpif)

--------
unit tests:

------------
make config changes, test runtime behavior

-- test runtime behavior --
continuously send packets to br0 with dest-mac=01:80:c2:00:00:00

ovs-dpctl dump-flows br0
ovs-vsctl set bridge br0 other-config:forward-bpdu=true
ovs-dpctl dump-flows br0
ovs-vsctl set bridge br0 other-config:forward-bpdu=false
ovs-dpctl dump-flows br0
ovs-vsctl set bridge br0 other-config:forward-bpdu=true
ovs-dpctl dump-flows br0
ovs-vsctl remove bridge br0 other-config forward-bpdu=true
ovs-dpctl dump-flows br0

--result--
 ovs-dpctl dump-flows br0
 in_port(1),eth(src=00:0c:29:d1:39:42,dst=01:80:c2:00:00:00), packets:29550, bytes:1773000, used:0.004s, actions:drop
 ovs-vsctl set bridge br0 other-config:forward-bpdu=true

 ovs-dpctl dump-flows br0
in_port(1),eth(src=00:0c:29:d1:39:42,dst=01:80:c2:00:00:00), packets:8209, bytes:492540, used:0.000s, actions:2,0

 ovs-vsctl set bridge br0 other-config:forward-bpdu=false
 ovs-dpctl dump-flows br0
in_port(1),eth(src=00:0c:29:d1:39:42,dst=01:80:c2:00:00:00), packets:19, bytes:1140, used:0.000s, actions:drop

 ovs-vsctl set bridge br0 other-config:forward-bpdu=true
 ovs-dpctl dump-flows br0
in_port(1),eth(src=00:0c:29:d1:39:42,dst=01:80:c2:00:00:00), packets:29, bytes:1740, used:0.000s, actions:2,0

 ovs-vsctl remove bridge br0 other-config forward-bpdu=true
 ovs-dpctl dump-flows br0
in_port(1),eth(src=00:0c:29:d1:39:42,dst=01:80:c2:00:00:00), packets:0, bytes:0, used:never, actions:drop

Bug #6624
Reported-by: Niklas Andersson <nandersson@nicira.com>

2 files changed, 26 insertions, 0 deletions

diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
index 94668a733..d99d6a1cd 100644
--- a/vswitchd/bridge.c
+++ b/vswitchd/bridge.c
@@ -150,6 +150,7 @@ static void bridge_refresh_ofp_port(struct bridge *);
 static void bridge_configure_datapath_id(struct bridge *);
 static void bridge_configure_flow_eviction_threshold(struct bridge *);
 static void bridge_configure_netflow(struct bridge *);
+static void bridge_configure_forward_bpdu(struct bridge *);
 static void bridge_configure_sflow(struct bridge *, int *sflow_bridge_number);
 static void bridge_configure_remotes(struct bridge *,
                                      const struct sockaddr_in *managers,
@@ -414,6 +415,7 @@ bridge_reconfigure(const struct ovsrec_open_vswitch *ovs_cfg)
         bridge_configure_mirrors(br);
         bridge_configure_datapath_id(br);
         bridge_configure_flow_eviction_threshold(br);
+        bridge_configure_forward_bpdu(br);
         bridge_configure_remotes(br, managers, n_managers);
         bridge_configure_netflow(br);
         bridge_configure_sflow(br, &sflow_bridge_number);
@@ -982,6 +984,20 @@ bridge_configure_flow_eviction_threshold(struct bridge *br)
     ofproto_set_flow_eviction_threshold(br->ofproto, threshold);
 }
 
+/* Set forward BPDU option. */
+static void
+bridge_configure_forward_bpdu(struct bridge *br)
+{
+    const char *forward_bpdu_str;
+    bool forward_bpdu = false;
+
+    forward_bpdu_str = bridge_get_other_config(br->cfg, "forward-bpdu");
+    if (forward_bpdu_str && !strcmp(forward_bpdu_str, "true")) {
+        forward_bpdu = true;
+    }
+    ofproto_set_forward_bpdu(br->ofproto, forward_bpdu);
+}
+
 static void
 bridge_pick_local_hw_addr(struct bridge *br, uint8_t ea[ETH_ADDR_LEN],
                           struct iface **hw_addr_iface)
diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index b8aa813c9..f56e670ae 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -461,6 +461,16 @@
 	  <dd>
             Values below 100 will be rounded up to 100.
           </dd>
+          <dt><code>forward-bpdu</code></dt>
+          <dd>
+            Option to allow forwarding of BPDU frames when NORMAL 
+            action if invoked. Frames with reserved Ethernet addresses 
+            (e.g. STP BPDU) will be forwarded when this option is enabled. 
+            If the Open vSwitch bridge is used to connect different
+            Ethernet networks, and if Open vSwtich node does not run STP, 
+            then this option should be enabled.    
+            Default is disabled, set to <code>true</code> to enable. 
+          </dd>
         </dl>
       </column>
     </group>