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, 15 insertions, 0 deletions

diff --git a/src/vnet/adj/adj.h b/src/vnet/adj/adj.h
index af7730f7086..32997c91f92 100644
--- a/src/vnet/adj/adj.h
+++ b/src/vnet/adj/adj.h
@@ -255,6 +255,15 @@ typedef struct ip_adjacency_t_
 
   /* Rewrite in second/third cache lines */
   vnet_declare_rewrite (VLIB_BUFFER_PRE_DATA_SIZE);
+
+  /**
+   * more control plane members that do not fit on the first cacheline
+   */
+  /**
+   * A sorted vector of delegates
+   */
+  struct adj_delegate_t_ *ia_delegates;
+
 } ip_adjacency_t;
 
 STATIC_ASSERT ((STRUCT_OFFSET_OF (ip_adjacency_t, cacheline0) == 0),
@@ -308,6 +317,12 @@ extern vnet_link_t adj_get_link_type (adj_index_t ai);
 extern u32 adj_get_sw_if_index (adj_index_t ai);
 
 /**
+ * @brief Return true if the adjacency is 'UP', i.e. can be used for forwarding.
+ * 0 is down, !0 is up.
+ */
+extern int adj_is_up (adj_index_t ai);
+
+/**
  * @brief Return the link type of the adjacency
  */
 extern const u8* adj_get_rewrite (adj_index_t ai);