Periodic scan and probe of IP neighbors to maintain neighbor pools

Scan IPv4 and IPv6 neigbor pool entries once a minute to keep them
up to date. The neighbor of an entry is probed if its time-stamp
is older than 1 minute. If the neighbor respond, its time-stamp
will be updated. If there is no response from a neighbor, its
entry will be deleted when the time-stamp of the entry become more
than 4 minutes old. Static neighbor entries are not probed nor
deleted.

Implemented CLI and API to enable and disable priodic scan of IPv4,
IPv6 or both types of IP neighbors. CLI is "ip scan-neighbor" and
API is "ip_scan_neighbor_enable_disable". Other IP neighbor scan
parameters can also be changed from their defaults via the CLI/API.

Change-Id: Id1a0a934ace15d03db845aa698bcbb9cdabebfcd
Signed-off-by: John Lo <loj@cisco.com>

2 files changed, 15 insertions, 4 deletions

diff --git a/src/vnet/ethernet/arp.c b/src/vnet/ethernet/arp.c
index 0d692cc1070..8df96f6a0f1 100644
--- a/src/vnet/ethernet/arp.c
+++ b/src/vnet/ethernet/arp.c
@@ -269,7 +269,7 @@ format_ethernet_arp_ip4_entry (u8 * s, va_list * va)
     flags = format (flags, "N");
 
   s = format (s, "%=12U%=16U%=6s%=20U%U",
-	      format_vlib_cpu_time, vnm->vlib_main, e->cpu_time_last_updated,
+	      format_vlib_time, vnm->vlib_main, e->time_last_updated,
 	      format_ip4_address, &e->ip4_address,
 	      flags ? (char *) flags : "",
 	      format_ethernet_address, e->ethernet_address,
@@ -616,14 +616,17 @@ vnet_arp_set_ip4_over_ethernet_internal (vnet_main_t * vnm,
        */
       if (0 == memcmp (e->ethernet_address,
 		       a->ethernet, sizeof (e->ethernet_address)))
-	goto check_customers;
+	{
+	  e->time_last_updated = vlib_time_now (vm);
+	  goto check_customers;
+	}
 
       /* Update time stamp and ethernet address. */
       clib_memcpy (e->ethernet_address, a->ethernet,
 		   sizeof (e->ethernet_address));
     }
 
-  e->cpu_time_last_updated = clib_cpu_time_now ();
+  e->time_last_updated = vlib_time_now (vm);
   if (is_static)
     e->flags |= ETHERNET_ARP_IP4_ENTRY_FLAG_STATIC;
   else
@@ -1300,6 +1303,13 @@ ip4_arp_entry_sort (void *a1, void *a2)
 }
 
 ethernet_arp_ip4_entry_t *
+ip4_neighbors_pool (void)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  return am->ip4_entry_pool;
+}
+
+ethernet_arp_ip4_entry_t *
 ip4_neighbor_entries (u32 sw_if_index)
 {
   ethernet_arp_main_t *am = &ethernet_arp_main;
diff --git a/src/vnet/ethernet/arp_packet.h b/src/vnet/ethernet/arp_packet.h
index 4b7b0482fb7..d2a23a5949f 100644
--- a/src/vnet/ethernet/arp_packet.h
+++ b/src/vnet/ethernet/arp_packet.h
@@ -156,7 +156,7 @@ typedef struct
 
   ethernet_arp_entry_flags_t flags;
 
-  u64 cpu_time_last_updated;
+  f64 time_last_updated;
 
   /**
    * The index of the adj-fib entry created
@@ -164,6 +164,7 @@ typedef struct
   fib_node_index_t fib_entry_index;
 } ethernet_arp_ip4_entry_t;
 
+ethernet_arp_ip4_entry_t *ip4_neighbors_pool (void);
 ethernet_arp_ip4_entry_t *ip4_neighbor_entries (u32 sw_if_index);
 u8 *format_ethernet_arp_ip4_entry (u8 * s, va_list * va);