Improve MTU handling

- setting MTU on an interface updates the L3 max bytes too
- value cached in the adjacency is also updated
- MTU exceeded generates ICMP to sender

Change-Id: I343ec71d8e903b529594c4bd0543f04bc7f370b3
Signed-off-by: Neale Ranns <neale.ranns@cisco.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/src/vnet/adj/adj.c b/src/vnet/adj/adj.c
index 5f7fe74cd43..d28d5195330 100644
--- a/src/vnet/adj/adj.c
+++ b/src/vnet/adj/adj.c
@@ -338,6 +338,43 @@ adj_feature_update (u32 sw_if_index,
     adj_walk (sw_if_index, adj_feature_update_walk_cb, &ctx);
 }
 
+static adj_walk_rc_t
+adj_mtu_update_walk_cb (adj_index_t ai,
+                        void *arg)
+{
+    ip_adjacency_t *adj;
+
+    adj = adj_get(ai);
+
+    vnet_rewrite_update_mtu (vnet_get_main(),
+                             &adj->rewrite_header);
+
+    return (ADJ_WALK_RC_CONTINUE);
+}
+
+static void
+adj_sw_mtu_update (vnet_main_t * vnm,
+                   u32 sw_if_index,
+                   void *ctx)
+{
+    /*
+     * Walk all the adjacencies on the interface to update the cached MTU
+     */
+    adj_walk (sw_if_index, adj_mtu_update_walk_cb, NULL);
+}
+
+void
+adj_mtu_update (u32 hw_if_index)
+{
+    /*
+     * Walk all the SW interfaces on the HW interface to update the cached MTU
+     */
+    vnet_hw_interface_walk_sw(vnet_get_main(),
+                              hw_if_index,
+                              adj_sw_mtu_update,
+                              NULL);
+}
+
 /**
  * @brief Walk the Adjacencies on a given interface
  */