BFD-FIB interactions

- single-hop BFD: attach a delegate to the appropriate adjacency
- multi-hop BFD [not supported yet]: attach a delegate to the FIB entry.

adjacency/fib_entry state tracks the BFD session state. when the state is down the object does not contribute forwarding hence and hence dependent objects will not use it.
For example, if a route is ECMP via two adjacencies and one of them is BFD down, then only the other is used to forward (i.e. we don't drop half the traffic).

Change-Id: I0ef53e20e73b067001a132cd0a3045408811a822
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/src/vnet/bfd/bfd_main.h b/src/vnet/bfd/bfd_main.h
index d722a55274c..93adac3dc8d 100644
--- a/src/vnet/bfd/bfd_main.h
+++ b/src/vnet/bfd/bfd_main.h
@@ -66,6 +66,20 @@ typedef enum
 #undef F
 } bfd_poll_state_e;
 
+/**
+ * hop types
+ */
+#define foreach_bfd_hop(F)                     \
+  F (SINGLE, "single")                         \
+  F (MULTI,  "multi")                          \
+
+typedef enum
+{
+#define F(sym, str) BFD_HOP_TYPE_##sym,
+  foreach_bfd_hop (F)
+#undef F
+} bfd_hop_type_e;
+
 typedef struct bfd_session_s
 {
   /** index in bfd_main.sessions pool */
@@ -77,6 +91,9 @@ typedef struct bfd_session_s
   /** remote session state */
   bfd_state_e remote_state;
 
+  /** BFD hop type */
+  bfd_hop_type_e hop_type;
+
   /** local diagnostics */
   bfd_diag_code_e local_diag;
 
@@ -220,6 +237,26 @@ typedef struct bfd_session_s
   };
 } bfd_session_t;
 
+/**
+ * listener events
+ */
+#define foreach_bfd_listen_event(F)            \
+  F (CREATE, "sesion-created")                 \
+  F (UPDATE, "session-updated")                \
+  F (DELETE, "session-deleted")
+
+typedef enum
+{
+#define F(sym, str) BFD_LISTEN_EVENT_##sym,
+  foreach_bfd_listen_event (F)
+#undef F
+} bfd_listen_event_e;
+
+/**
+ * session nitification call back function type
+ */
+typedef void (*bfd_notify_fn_t) (bfd_listen_event_e, const bfd_session_t *);
+
 typedef struct
 {
   /** pool of bfd sessions context data */
@@ -259,6 +296,8 @@ typedef struct
   /** hashmap - index in pool auth_keys by conf_key_id */
   u32 *auth_key_by_conf_key_id;
 
+  /** A vector of callback notification functions */
+  bfd_notify_fn_t *listeners;
 } bfd_main_t;
 
 extern bfd_main_t bfd_main;
@@ -345,6 +384,11 @@ const char *bfd_poll_state_string (bfd_poll_state_e state);
  */
 #define BFD_REQUIRED_MIN_RX_USEC_WHILE_ECHO USEC_PER_SECOND
 
+/**
+ * Register a callback function to receive session notifications.
+ */
+void bfd_register_listener (bfd_notify_fn_t fn);
+
 #endif /* __included_bfd_main_h__ */
 
 /*