linux-cp: handle ipv4 routes when link goes down

Type: improvement

Currently, when the link goes down on an interface, routes that resolve
through that interface and created with Nexthop API are removed by the
kernel. However, IPv4 routes remain in the FIB because the kernel
doesn't send any notifications about that.

And for the plugin working with user-space applications that create
routes in the kernel using Nexthop API there should be a mechanism to
synchronize the FIB and the kernel in this case.

With this change, add two new startup configuration options to the
plugin to be able to control what should happen with static and dynamic
routes managed by the plugin on link down:
  - del-static-on-link-down (disabled by default, delete routes created
    with the linux-cp static FIB source on link down),
  - del-dynamic-on-link-down (disabled by default, delete routes created
    with the linux-cp dynamic FIB source on link down).

Then, monitor link state changes on interfaces for which a linux-cp pair
exists. If the link goes down on one of the interfaces, process routes
that resolve through that interface according to the new configurations.

Signed-off-by: Alexander Chernavin <achernavin@netgate.com>
Change-Id: I0fbaeeca3f3d1fcd22e8eebb08a0a4a3d0dfe5b8

1 files changed, 14 insertions, 0 deletions

diff --git a/src/plugins/linux-cp/lcp.h b/src/plugins/linux-cp/lcp.h
index 14c1a6e2a75..4ddaa3898d6 100644
--- a/src/plugins/linux-cp/lcp.h
+++ b/src/plugins/linux-cp/lcp.h
@@ -26,6 +26,8 @@ typedef struct lcp_main_s
   int default_ns_fd;
   u8 lcp_auto_subint; /* Automatically create/delete LCP sub-interfaces */
   u8 lcp_sync;	      /* Automatically sync VPP changes to LCP */
+  u8 del_static_on_link_down;  /* Delete static routes when link goes down */
+  u8 del_dynamic_on_link_down; /* Delete dynamic routes when link goes down */
   u8 test_mode;	      /* Set when Unit testing */
 } lcp_main_t;
 
@@ -38,6 +40,18 @@ int lcp_set_default_ns (u8 *ns);
 u8 *lcp_get_default_ns (void); /* Returns NULL or shared string */
 int lcp_get_default_ns_fd (void);
 
+/**
+ * Get/Set whether to delete static routes when the link goes down.
+ */
+void lcp_set_del_static_on_link_down (u8 is_del);
+u8 lcp_get_del_static_on_link_down (void);
+
+/**
+ * Get/Set whether to delete dynamic routes when the link goes down.
+ */
+void lcp_set_del_dynamic_on_link_down (u8 is_del);
+u8 lcp_get_del_dynamic_on_link_down (void);
+
 #endif
 
 /*