vswitchd: Make the MAC entry aging time configurable.

NICS-11.
Signed-off-by: Ben Pfaff <blp@nicira.com>

10 files changed, 111 insertions, 15 deletions

diff --git a/NEWS b/NEWS
index c9616af0..735c863e 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,8 @@ v1.5.0 - xx xxx xxxx
           {=}, {!=}, {<}, {>}, {<=}, and {>=}.
     - ovsdb-tool now uses the typical database and schema installation
       directories as defaults.
+    - The default MAC learning timeout has been increased from 60 seconds
+      to 300 seconds.  The MAC learning timeout is now configurable.
 
 
 v1.4.0 - 30 Jan 2012
diff --git a/lib/learning-switch.c b/lib/learning-switch.c
index 2fc6392f..05eb578c 100644
--- a/lib/learning-switch.c
+++ b/lib/learning-switch.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -96,7 +96,9 @@ lswitch_create(struct rconn *rconn, const struct lswitch_config *cfg)
     sw->max_idle = cfg->max_idle;
     sw->datapath_id = 0;
     sw->last_features_request = time_now() - 1;
-    sw->ml = cfg->mode == LSW_LEARN ? mac_learning_create() : NULL;
+    sw->ml = (cfg->mode == LSW_LEARN
+              ? mac_learning_create(MAC_ENTRY_DEFAULT_IDLE_TIME)
+              : NULL);
     sw->action_normal = cfg->mode == LSW_NORMAL;
 
     flow_wildcards_init_exact(&sw->wc);
diff --git a/lib/mac-learning.c b/lib/mac-learning.c
index efd1dd4b..836bcd48 100644
--- a/lib/mac-learning.c
+++ b/lib/mac-learning.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,12 +37,12 @@ VLOG_DEFINE_THIS_MODULE(mac_learning);
 COVERAGE_DEFINE(mac_learning_learned);
 COVERAGE_DEFINE(mac_learning_expired);
 
-/* Returns the number of seconds since 'e' was last learned. */
+/* Returns the number of seconds since 'e' (within 'ml') was last learned. */
 int
-mac_entry_age(const struct mac_entry *e)
+mac_entry_age(const struct mac_learning *ml, const struct mac_entry *e)
 {
     time_t remaining = e->expires - time_now();
-    return MAC_ENTRY_IDLE_TIME - remaining;
+    return ml->idle_time - remaining;
 }
 
 static uint32_t
@@ -98,9 +98,18 @@ get_lru(struct mac_learning *ml, struct mac_entry **e)
     }
 }
 
-/* Creates and returns a new MAC learning table. */
+static unsigned int
+normalize_idle_time(unsigned int idle_time)
+{
+    return (idle_time < 15 ? 15
+            : idle_time > 3600 ? 3600
+            : idle_time);
+}
+
+/* Creates and returns a new MAC learning table with an initial MAC aging
+ * timeout of 'idle_time' seconds. */
 struct mac_learning *
-mac_learning_create(void)
+mac_learning_create(unsigned int idle_time)
 {
     struct mac_learning *ml;
 
@@ -109,6 +118,7 @@ mac_learning_create(void)
     hmap_init(&ml->table);
     ml->secret = random_uint32();
     ml->flood_vlans = NULL;
+    ml->idle_time = normalize_idle_time(idle_time);
     return ml;
 }
 
@@ -146,6 +156,23 @@ mac_learning_set_flood_vlans(struct mac_learning *ml,
     }
 }
 
+/* Changes the MAC aging timeout of 'ml' to 'idle_time' seconds. */
+void
+mac_learning_set_idle_time(struct mac_learning *ml, unsigned int idle_time)
+{
+    idle_time = normalize_idle_time(idle_time);
+    if (idle_time != ml->idle_time) {
+        struct mac_entry *e;
+        int delta;
+
+        delta = (int) idle_time - (int) ml->idle_time;
+        LIST_FOR_EACH (e, lru_node, &ml->lrus) {
+            e->expires += delta;
+        }
+        ml->idle_time = idle_time;
+    }
+}
+
 static bool
 is_learning_vlan(const struct mac_learning *ml, uint16_t vlan)
 {
@@ -199,7 +226,7 @@ mac_learning_insert(struct mac_learning *ml,
 
     /* Mark 'e' as recently used. */
     list_push_back(&ml->lrus, &e->lru_node);
-    e->expires = time_now() + MAC_ENTRY_IDLE_TIME;
+    e->expires = time_now() + ml->idle_time;
 
     return e;
 }
diff --git a/lib/mac-learning.h b/lib/mac-learning.h
index 4bcf221d..8d0ac622 100644
--- a/lib/mac-learning.h
+++ b/lib/mac-learning.h
@@ -24,10 +24,12 @@
 #include "tag.h"
 #include "timeval.h"
 
+struct mac_learning;
+
 #define MAC_MAX 2048
 
 /* Time, in seconds, before expiring a mac_entry due to inactivity. */
-#define MAC_ENTRY_IDLE_TIME 300
+#define MAC_ENTRY_DEFAULT_IDLE_TIME 300
 
 /* Time, in seconds, to lock an entry updated by a gratuitous ARP to avoid
  * relearning based on a reflection from a bond slave. */
@@ -50,7 +52,7 @@ struct mac_entry {
     } port;
 };
 
-int mac_entry_age(const struct mac_entry *);
+int mac_entry_age(const struct mac_learning *, const struct mac_entry *);
 
 /* Returns true if mac_learning_insert() just created 'mac' and the caller has
  * not yet properly initialized it. */
@@ -80,10 +82,11 @@ struct mac_learning {
                                    front, most recently used at the back. */
     uint32_t secret;            /* Secret for randomizing hash table. */
     unsigned long *flood_vlans; /* Bitmap of learning disabled VLANs. */
+    unsigned int idle_time;     /* Max age before deleting an entry. */
 };
 
 /* Basics. */
-struct mac_learning *mac_learning_create(void);
+struct mac_learning *mac_learning_create(unsigned int idle_time);
 void mac_learning_destroy(struct mac_learning *);
 
 void mac_learning_run(struct mac_learning *, struct tag_set *);
@@ -92,6 +95,7 @@ void mac_learning_wait(struct mac_learning *);
 /* Configuration. */
 bool mac_learning_set_flood_vlans(struct mac_learning *,
                                   const unsigned long *bitmap);
+void mac_learning_set_idle_time(struct mac_learning *, unsigned int idle_time);
 
 /* Learning. */
 bool mac_learning_may_learn(const struct mac_learning *,
diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
index b6e42f83..cd27528c 100644
--- a/ofproto/ofproto-dpif.c
+++ b/ofproto/ofproto-dpif.c
@@ -651,7 +651,7 @@ construct(struct ofproto *ofproto_, int *n_tablesp)
     ofproto->sflow = NULL;
     ofproto->stp = NULL;
     hmap_init(&ofproto->bundles);
-    ofproto->ml = mac_learning_create();
+    ofproto->ml = mac_learning_create(MAC_ENTRY_DEFAULT_IDLE_TIME);
     for (i = 0; i < MAX_MIRRORS; i++) {
         ofproto->mirrors[i] = NULL;
     }
@@ -2136,6 +2136,13 @@ forward_bpdu_changed(struct ofproto *ofproto_)
     /* Revalidate cached flows whenever forward_bpdu option changes. */
     ofproto->need_revalidate = true;
 }
+
+static void
+set_mac_idle_time(struct ofproto *ofproto_, unsigned int idle_time)
+{
+    struct ofproto_dpif *ofproto = ofproto_dpif_cast(ofproto_);
+    mac_learning_set_idle_time(ofproto->ml, idle_time);
+}
 
 /* Ports. */
 
@@ -5684,7 +5691,8 @@ ofproto_unixctl_fdb_show(struct unixctl_conn *conn, int argc OVS_UNUSED,
         struct ofbundle *bundle = e->port.p;
         ds_put_format(&ds, "%5d  %4d  "ETH_ADDR_FMT"  %3d\n",
                       ofbundle_get_a_port(bundle)->odp_port,
-                      e->vlan, ETH_ADDR_ARGS(e->mac), mac_entry_age(e));
+                      e->vlan, ETH_ADDR_ARGS(e->mac),
+                      mac_entry_age(ofproto->ml, e));
     }
     unixctl_command_reply(conn, 200, ds_cstr(&ds));
     ds_destroy(&ds);
@@ -6120,5 +6128,6 @@ const struct ofproto_class ofproto_dpif_class = {
     set_flood_vlans,
     is_mirror_output_bundle,
     forward_bpdu_changed,
+    set_mac_idle_time,
     set_realdev,
 };
diff --git a/ofproto/ofproto-provider.h b/ofproto/ofproto-provider.h
index 6c8583ea..6dd206b9 100644
--- a/ofproto/ofproto-provider.h
+++ b/ofproto/ofproto-provider.h
@@ -1064,6 +1064,10 @@ struct ofproto_class {
      * will be invoked. */
     void (*forward_bpdu_changed)(struct ofproto *ofproto);
 
+    /* Sets the MAC aging timeout for the OFPP_NORMAL action to 'idle_time',
+     * in seconds. */
+    void (*set_mac_idle_time)(struct ofproto *ofproto, unsigned int idle_time);
+
 /* Linux VLAN device support (e.g. "eth0.10" for VLAN 10.)
  *
  * This is deprecated.  It is only for compatibility with broken device drivers
diff --git a/ofproto/ofproto.c b/ofproto/ofproto.c
index 07d4934b..aad63331 100644
--- a/ofproto/ofproto.c
+++ b/ofproto/ofproto.c
@@ -446,6 +446,16 @@ ofproto_set_forward_bpdu(struct ofproto *ofproto, bool forward_bpdu)
     }
 }
 
+/* Sets the MAC aging timeout for the OFPP_NORMAL action on 'ofproto' to
+ * 'idle_time', in seconds. */
+void
+ofproto_set_mac_idle_time(struct ofproto *ofproto, unsigned idle_time)
+{
+    if (ofproto->ofproto_class->set_mac_idle_time) {
+        ofproto->ofproto_class->set_mac_idle_time(ofproto, idle_time);
+    }
+}
+
 void
 ofproto_set_desc(struct ofproto *p,
                  const char *mfr_desc, const char *hw_desc,
diff --git a/ofproto/ofproto.h b/ofproto/ofproto.h
index 2d478784..24efa155 100644
--- a/ofproto/ofproto.h
+++ b/ofproto/ofproto.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009, 2010, 2011 Nicira Networks.
+ * Copyright (c) 2009, 2010, 2011, 2012 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -205,6 +205,7 @@ void ofproto_set_extra_in_band_remotes(struct ofproto *,
 void ofproto_set_in_band_queue(struct ofproto *, int queue_id);
 void ofproto_set_flow_eviction_threshold(struct ofproto *, unsigned threshold);
 void ofproto_set_forward_bpdu(struct ofproto *, bool forward_bpdu);
+void ofproto_set_mac_idle_time(struct ofproto *, unsigned idle_time);
 void ofproto_set_desc(struct ofproto *,
                       const char *mfr_desc, const char *hw_desc,
                       const char *sw_desc, const char *serial_desc,
diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
index b45b9727..261a3622 100644
--- a/vswitchd/bridge.c
+++ b/vswitchd/bridge.c
@@ -32,6 +32,7 @@
 #include "jsonrpc.h"
 #include "lacp.h"
 #include "list.h"
+#include "mac-learning.h"
 #include "netdev.h"
 #include "ofp-print.h"
 #include "ofpbuf.h"
@@ -156,6 +157,7 @@ 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_mac_idle_time(struct bridge *);
 static void bridge_configure_sflow(struct bridge *, int *sflow_bridge_number);
 static void bridge_configure_stp(struct bridge *);
 static void bridge_configure_remotes(struct bridge *,
@@ -465,6 +467,7 @@ bridge_reconfigure(const struct ovsrec_open_vswitch *ovs_cfg)
         bridge_configure_mirrors(br);
         bridge_configure_flow_eviction_threshold(br);
         bridge_configure_forward_bpdu(br);
+        bridge_configure_mac_idle_time(br);
         bridge_configure_remotes(br, managers, n_managers);
         bridge_configure_netflow(br);
         bridge_configure_sflow(br, &sflow_bridge_number);
@@ -1271,6 +1274,20 @@ bridge_configure_forward_bpdu(struct bridge *br)
     ofproto_set_forward_bpdu(br->ofproto, forward_bpdu);
 }
 
+/* Set MAC aging time for 'br'. */
+static void
+bridge_configure_mac_idle_time(struct bridge *br)
+{
+    const char *idle_time_str;
+    int idle_time;
+
+    idle_time_str = bridge_get_other_config(br->cfg, "mac-aging-time");
+    idle_time = (idle_time_str && atoi(idle_time_str)
+                 ? atoi(idle_time_str)
+                 : MAC_ENTRY_DEFAULT_IDLE_TIME);
+    ofproto_set_mac_idle_time(br->ofproto, idle_time);
+}
+
 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 e28b053b..f3545e5a 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -553,6 +553,26 @@
         should be enabled.  Default is disabled, set to
         <code>true</code> to enable.
       </column>
+
+      <column name="other_config" key="mac-aging-time"
+              type='{"type": "integer", "minInteger": 1}'>
+        <p>
+          The maximum number of seconds to retain a MAC learning entry for
+          which no packets have been seen.  The default is currently 300
+          seconds (5 minutes).  The value, if specified, is forced into a
+          reasonable range, currently 15 to 3600 seconds.
+        </p>
+
+        <p>
+          A short MAC aging time allows a network to more quickly detect that a
+          host is no longer connected to a switch port.  However, it also makes
+          it more likely that packets will be flooded unnecessarily, when they
+          are addressed to a connected host that rarely transmits packets.  To
+          reduce the incidence of unnecessary flooding, use a MAC aging time
+          longer than the maximum interval at which a host will ordinarily
+          transmit packets.
+        </p>
+      </column>
     </group>
 
     <group title="Bridge Status">