isisd: apply fast-reroute on an adjacency failure

When a adjacency falls down, the primary routes are not deleted on the
dataplane until the SPF is recomputed. Even the backup routes are
pre-installed on the dataplane, there is no fast-route optimization.

Reasons for an adjacency to come down are:
- BFD down
- Hello timer timeout
- User adjacency clear

Apply the backup route switchover for fast-reroute as soon an IS-IS
adjacency falls down before the first SPF re-computation. Pre-computed
backup routes are applied sooner.

Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/isisd/isis_circuit.c b/isisd/isis_circuit.c
index fedceed3bb..3bbdaac649 100644
--- a/isisd/isis_circuit.c
+++ b/isisd/isis_circuit.c
@@ -604,6 +604,27 @@ size_t isis_circuit_pdu_size(struct isis_circuit *circuit)
 	return ISO_MTU(circuit);
 }
 
+static bool isis_circuit_lfa_enabled(struct isis_circuit *circuit, int level)
+{
+	return (circuit->lfa_protection[level - 1] ||
+		circuit->rlfa_protection[level - 1] ||
+		circuit->tilfa_protection[level - 1]);
+}
+
+void isis_circuit_switchover_routes(struct isis_circuit *circuit, int family,
+				    union g_addr *nexthop_ip, ifindex_t ifindex)
+{
+	char is_type = circuit->area->is_type;
+	if ((is_type == IS_LEVEL_1 || is_type == IS_LEVEL_1_AND_2) &&
+	    isis_circuit_lfa_enabled(circuit, IS_LEVEL_1))
+		isis_area_switchover_routes(circuit->area, family, nexthop_ip,
+					    ifindex, IS_LEVEL_1);
+	if ((is_type == IS_LEVEL_2 || is_type == IS_LEVEL_1_AND_2) &&
+	    isis_circuit_lfa_enabled(circuit, IS_LEVEL_2))
+		isis_area_switchover_routes(circuit->area, family, nexthop_ip,
+					    ifindex, IS_LEVEL_2);
+}
+
 void isis_circuit_stream(struct isis_circuit *circuit, struct stream **stream)
 {
 	size_t stream_size = isis_circuit_pdu_size(circuit);