vswitch: Send gratuitous learning packets when bond slaves go down.

When a bond slave goes down, all of the MACs that were on it are migrated
to another slave, but this is not apparent to the switch that the bond is
connected to until each MAC sends out a packet.  This causes incoming
traffic for a given MAC to be dropped until the MAC sends out a packet.
This is not usually a problem, because traffic is not ordinarily one-way,
and we can't avoid losing some packets in some cases, but we can do a
little better by sending out a gratuitous learning packet on the new slave
as soon as we know about it, and that is what this commit implements.

Bug #1290.

diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
index ff5d352..8d0a2ef 100644 (file)
--- a/vswitchd/bridge.c
+++ b/vswitchd/bridge.c
@@ -218,6 +218,7 @@ static uint64_t dpid_from_hash(const void *, size_t nbytes);
 static void bond_run(struct bridge *);
 static void bond_wait(struct bridge *);
 static void bond_rebalance_port(struct port *);
+static void bond_send_learning_packets(struct port *);
 
 static void port_create(struct bridge *, const char *name);
 static void port_reconfigure(struct port *);
@@ -482,7 +483,6 @@ bridge_reconfigure(void)
         bool add_id_to_iface = false;
         struct svec nf_hosts;
 
-
         bridge_fetch_dp_ifaces(br);
         for (i = 0; i < br->n_ports; ) {
             struct port *port = br->ports[i];
@@ -1279,7 +1279,7 @@ bond_choose_iface(const struct port *port)
 }
 
 static bool
-choose_output_iface(const struct port *port, const flow_t *flow,
+choose_output_iface(const struct port *port, const uint8_t *dl_src,
                     uint16_t *dp_ifidx, tag_type *tags)
 {
     struct iface *iface;
@@ -1288,7 +1288,7 @@ choose_output_iface(const struct port *port, const flow_t *flow,
     if (port->n_ifaces == 1) {
         iface = port->ifaces[0];
     } else {
-        struct bond_entry *e = lookup_bond_entry(port, flow->dl_src);
+        struct bond_entry *e = lookup_bond_entry(port, dl_src);
         if (e->iface_idx < 0 || e->iface_idx >= port->n_ifaces
             || !port->ifaces[e->iface_idx]->enabled) {
             /* XXX select interface properly.  The current interface selection
@@ -1379,10 +1379,12 @@ bond_run(struct bridge *br)
                                            port->active_iface_tag);
                         bond_choose_active_iface(port);
                     }
+                    bond_send_learning_packets(port);
                 } else {
                     if (port->active_iface < 0) {
                         ofproto_revalidate(br->ofproto, port->no_ifaces_tag);
                         bond_choose_active_iface(port);
+                        bond_send_learning_packets(port);
                     }
                     iface->tag = tag_create_random();
                 }
@@ -1430,7 +1432,7 @@ set_dst(struct dst *p, const flow_t *flow,
     p->vlan = (out_port->vlan >= 0 ? OFP_VLAN_NONE
               : in_port->vlan >= 0 ? in_port->vlan
               : ntohs(flow->dl_vlan));
-    return choose_output_iface(out_port, flow, &p->dp_ifidx, tags);
+    return choose_output_iface(out_port, flow->dl_src, &p->dp_ifidx, tags);
 }
 
 static void
@@ -1908,6 +1910,8 @@ static struct ofhooks bridge_ofhooks = {
     bridge_account_checkpoint_ofhook_cb,
 };
 \f
+/* Bonding functions. */
+
 /* Statistics for a single interface on a bonded port, used for load-based
  * bond rebalancing.  */
 struct slave_balance {
@@ -2167,6 +2171,89 @@ bond_rebalance_port(struct port *port)
         e->tx_bytes /= 2;
     }
 }
+
+static void
+bond_send_learning_packets(struct port *port)
+{
+    struct bridge *br = port->bridge;
+    struct mac_entry *e;
+    struct ofpbuf packet;
+    int error, n_packets, n_errors;
+
+    if (!port->n_ifaces || port->active_iface < 0 || !br->ml) {
+        return;
+    }
+
+    ofpbuf_init(&packet, 128);
+    error = n_packets = n_errors = 0;
+    LIST_FOR_EACH (e, struct mac_entry, lru_node, &br->ml->lrus) {
+        static const char s[] = "Open vSwitch Bond Failover";
+        union ofp_action actions[2], *a;
+        struct eth_header *eth;
+        struct llc_snap_header *llc_snap;
+        uint16_t dp_ifidx;
+        tag_type tags = 0;
+        flow_t flow;
+        int retval;
+
+        if (e->port == port->port_idx
+            || !choose_output_iface(port, e->mac, &dp_ifidx, &tags)) {
+            continue;
+        }
+
+        /* Compose packet to send. */
+        ofpbuf_clear(&packet);
+        eth = ofpbuf_put_zeros(&packet, ETH_HEADER_LEN);
+        llc_snap = ofpbuf_put_zeros(&packet, LLC_SNAP_HEADER_LEN);
+        ofpbuf_put(&packet, s, sizeof s); /* Includes null byte. */
+        ofpbuf_put(&packet, e->mac, ETH_ADDR_LEN);
+
+        memcpy(eth->eth_dst, eth_addr_broadcast, ETH_ADDR_LEN);
+        memcpy(eth->eth_src, e->mac, ETH_ADDR_LEN);
+        eth->eth_type = htons(packet.size - ETH_HEADER_LEN);
+
+        llc_snap->llc.llc_dsap = LLC_DSAP_SNAP;
+        llc_snap->llc.llc_ssap = LLC_SSAP_SNAP;
+        llc_snap->llc.llc_cntl = LLC_CNTL_SNAP;
+        memcpy(llc_snap->snap.snap_org, "\x00\x23\x20", 3);
+        llc_snap->snap.snap_type = htons(0xf177); /* Random number. */
+
+        /* Compose actions. */
+        memset(actions, 0, sizeof actions);
+        a = actions;
+        if (e->vlan) {
+            a->vlan_vid.type = htons(OFPAT_SET_VLAN_VID);
+            a->vlan_vid.len = htons(sizeof *a);
+            a->vlan_vid.vlan_vid = htons(e->vlan);
+            a++;
+        }
+        a->output.type = htons(OFPAT_OUTPUT);
+        a->output.len = htons(sizeof *a);
+        a->output.port = htons(odp_port_to_ofp_port(dp_ifidx));
+        a++;
+
+        /* Send packet. */
+        n_packets++;
+        flow_extract(&packet, ODPP_NONE, &flow);
+        retval = ofproto_send_packet(br->ofproto, &flow, actions, a - actions,
+                                     &packet);
+        if (retval) {
+            error = retval;
+            n_errors++;
+        }
+    }
+    ofpbuf_uninit(&packet);
+
+    if (n_errors) {
+        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
+        VLOG_WARN_RL(&rl, "bond %s: %d errors sending %d gratuitous learning "
+                     "packets, last error was: %s",
+                     port->name, n_errors, n_packets, strerror(error));
+    } else {
+        VLOG_DBG("bond %s: sent %d gratuitous learning packets",
+                 port->name, n_packets);
+    }
+}
 \f
 /* Port functions. */
 
@@ -2517,6 +2604,7 @@ iface_destroy(struct iface *iface)
         if (del_active) {
             ofproto_revalidate(port->bridge->ofproto, port->active_iface_tag);
             bond_choose_active_iface(port);
+            bond_send_learning_packets(port);
         }
 
         port_update_bonding(port);