Merge pull request #6385 from GalaxyGorilla/bfd_igp_topotest

isis: tests: Fast RIB recovery from BFD recognized link failures

doc/user/bfd.rst

@@ -143,7 +143,7 @@ BFD peers and profiles share the same BFD session configuration commands.
 .. clicmd:: transmit-interval (10-60000)
 
    The minimum transmission interval (less jitter) that this system
-   wants to use to send BFD control packets.
+   wants to use to send BFD control packets. Defaults to 300ms.
 
 .. index:: echo-interval (10-60000)
 .. clicmd:: echo-interval (10-60000)
@@ -159,7 +159,7 @@ BFD peers and profiles share the same BFD session configuration commands.
 
    It is recommended that the transmission interval of control packets
    to be increased after enabling echo-mode to reduce bandwidth usage.
-   For example: `transmission-interval 2000`.
+   For example: `transmit-interval 2000`.
 
    Echo mode is not supported on multi-hop setups (see :rfc:`5883`
    section 3).
@@ -246,6 +246,30 @@ The following commands are available inside the BGP configuration node.
    Removes the BFD profile configuration from peer session(s).
 
 
+.. _bfd-isis-peer-config:
+
+IS-IS BFD Configuration
+-----------------------
+
+The following commands are available inside the interface configuration node.
+
+.. index:: isis bfd
+.. clicmd:: ip isis bfd
+
+   Listen for BFD events on peers created on the interface. Every time
+   a new neighbor is found a BFD peer is created to monitor the link
+   status for fast convergence.
+
+.. index:: no isis bfd
+.. clicmd:: no isis bfd
+
+   Removes any notification registration for this interface peers.
+
+   Note that there will be just one BFD session per interface. In case both
+   IPv4 and IPv6 support are configured then just a IPv6 based session is
+   created.
+
+
 .. _bfd-ospf-peer-config:
 
 OSPF BFD Configuration

isisd/isis_adjacency.c

@@ -171,14 +171,14 @@ void isis_delete_adj(void *arg)
 		return;
 
 	THREAD_TIMER_OFF(adj->t_expire);
-	if (adj->adj_state != ISIS_ADJ_DOWN) {
+	if (adj->adj_state != ISIS_ADJ_DOWN)
 		adj->adj_state = ISIS_ADJ_DOWN;
-		hook_call(isis_adj_state_change_hook, adj);
-	}
 
 	/* remove from SPF trees */
 	spftree_area_adj_del(adj->circuit->area, adj);
 
+	hook_call(isis_adj_state_change_hook, adj);
+
 	XFREE(MTYPE_ISIS_ADJACENCY_INFO, adj->area_addresses);
 	XFREE(MTYPE_ISIS_ADJACENCY_INFO, adj->ipv4_addresses);
 	XFREE(MTYPE_ISIS_ADJACENCY_INFO, adj->ipv6_addresses);

isisd/isis_bfd.c

@@ -138,6 +138,8 @@ static void bfd_adj_event(struct isis_adjacency *adj, struct prefix *dst,
 		return;
 	}
 
+	adj->circuit->area->bfd_signalled_down = true;
+
 	isis_adj_state_change(&adj, ISIS_ADJ_DOWN, "bfd session went down");
 }
 

isisd/isis_lsp.c

@@ -1376,7 +1376,13 @@ static int lsp_refresh(struct thread *thread)
 	if ((area->is_type & level) == 0)
 		return ISIS_ERROR;
 
-	if (monotime_since(&area->last_lsp_refresh_event[level - 1], NULL) < 100000L) {
+	/*
+	 * Throttle regeneration of LSPs (but not when BFD signalled a 'down'
+	 * message)
+	 */
+	if (monotime_since(&area->last_lsp_refresh_event[level - 1], NULL)
+		    < 100000L
+	    && !(area->bfd_force_spf_refresh)) {
 		sched_debug("ISIS (%s): Still unstable, postpone LSP L%d refresh",
 			    area->area_tag, level);
 		_lsp_regenerate_schedule(area, level, 0, false,
@@ -1429,7 +1435,12 @@ int _lsp_regenerate_schedule(struct isis_area *area, int level,
 			"ISIS (%s): Checking whether L%d needs to be scheduled",
 			area->area_tag, lvl);
 
-		if (area->lsp_regenerate_pending[lvl - 1]) {
+		if (area->lsp_regenerate_pending[lvl - 1]
+		    && !(area->bfd_signalled_down)) {
+			/*
+			 * Note: in case of a BFD 'down' message the refresh is
+			 * scheduled once again just to be sure
+			 */
 			struct timeval remain = thread_timer_remain(
 				area->t_lsp_refresh[lvl - 1]);
 			sched_debug(
@@ -1457,7 +1468,8 @@ int _lsp_regenerate_schedule(struct isis_area *area, int level,
 			(long long)now);
 		THREAD_TIMER_OFF(area->t_lsp_refresh[lvl - 1]);
 		diff = now - lsp->last_generated;
-		if (diff < area->lsp_gen_interval[lvl - 1]) {
+		if (diff < area->lsp_gen_interval[lvl - 1]
+		    && !(area->bfd_signalled_down)) {
 			timeout =
 				1000 * (area->lsp_gen_interval[lvl - 1] - diff);
 			sched_debug(
@@ -1465,17 +1477,21 @@ int _lsp_regenerate_schedule(struct isis_area *area, int level,
 				area->area_tag, timeout);
 		} else {
 			/*
-			 * lsps are not regenerated if lsp_regenerate function
+			 * Schedule LSP refresh ASAP
-			 * is called
-			 * directly. However if the lsp_regenerate call is
-			 * queued for
-			 * later execution it works.
 			 */
-			timeout = 100;
+			timeout = 0;
-			sched_debug(
+
-				"ISIS (%s): Last generation was more than lsp_gen_interval ago."
+			if (area->bfd_signalled_down) {
-				" Scheduling for execution in %ld ms.",
+				sched_debug(
-				area->area_tag, timeout);
+					"ISIS (%s): Scheduling immediately due to BDF 'down' message.",
+					area->area_tag);
+				area->bfd_signalled_down = false;
+				area->bfd_force_spf_refresh = true;
+			} else {
+				sched_debug(
+					"ISIS (%s): Last generation was more than lsp_gen_interval ago. Scheduling for execution now.",
+					area->area_tag);
+			}
 		}
 
 		area->lsp_regenerate_pending[lvl - 1] = 1;

isisd/isis_spf.c

@@ -1288,9 +1288,20 @@ int _isis_spf_schedule(struct isis_area *area, int level,
 
 	/* wait configured min_spf_interval before doing the SPF */
 	long timer;
-	if (diff >= area->min_spf_interval[level - 1]) {
+	if (diff >= area->min_spf_interval[level - 1]
-		/* Last run is more than min interval ago, schedule immediate run */
+	    || area->bfd_force_spf_refresh) {
+		/*
+		 * Last run is more than min interval ago or BFD signalled a
+		 * 'down' message, schedule immediate run
+		 */
 		timer = 0;
+
+		if (area->bfd_force_spf_refresh) {
+			zlog_debug(
+				"ISIS-Spf (%s) L%d SPF scheduled immediately due to BFD 'down' message",
+				area->area_tag, level);
+			area->bfd_force_spf_refresh = false;
+		}
 	} else {
 		timer = area->min_spf_interval[level - 1] - diff;
 	}

isisd/isisd.c

@@ -203,6 +203,9 @@ struct isis_area *isis_area_create(const char *area_tag)
 	area->lsp_refresh_arg[1].area = area;
 	area->lsp_refresh_arg[1].level = IS_LEVEL_2;
 
+	area->bfd_signalled_down = false;
+	area->bfd_force_spf_refresh = false;
+
 
 	QOBJ_REG(area, isis_area);
 

isisd/isisd.h

@@ -127,6 +127,9 @@ struct isis_area {
 	 */
 	int lsp_regenerate_pending[ISIS_LEVELS];
 
+	bool bfd_signalled_down;
+	bool bfd_force_spf_refresh;
+
 	struct fabricd *fabricd;
 
 	/*

tests/topotests/bfd-isis-topo1/rt1/bfdd.conf

@@ -0,0 +1,17 @@
+!
+debug bfd network
+debug bfd peer
+debug bfd zebra
+!
+bfd
+ peer 10.0.1.2 interface eth-rt2
+  detect-multiplier 3
+  receive-interval 300
+  transmit-interval 300
+ !
+ peer 10.0.2.2 interface eth-rt3
+  detect-multiplier 3
+  receive-interval 300
+  transmit-interval 300
+ !
+!

tests/topotests/bfd-isis-topo1/rt1/isisd.conf

@@ -0,0 +1,35 @@
+log file isisd.log
+log timestamp precision 3
+!
+hostname rt1
+!
+password 1
+!
+debug isis events
+debug isis route-events
+debug isis spf-events
+debug isis adj-packets
+debug isis lsp-sched
+!
+interface lo
+ ip router isis 1
+ ipv6 router isis 1
+ isis passive
+!
+interface eth-rt2
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+ isis bfd
+!
+interface eth-rt3
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+ isis network point-to-point
+ isis bfd
+!
+router isis 1
+ net 49.0000.0000.0000.0001.00
+ is-type level-1
+!

tests/topotests/bfd-isis-topo1/rt1/step1/show_ip_route.ref

@@ -0,0 +1,74 @@
+{
+  "2.2.2.2\/32":[
+    {
+      "prefix":"2.2.2.2\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.1.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "3.3.3.3\/32":[
+    {
+      "prefix":"3.3.3.3\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.2.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "4.4.4.4\/32":[
+    {
+      "prefix":"4.4.4.4\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.2.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "5.5.5.5\/32":[
+    {
+      "prefix":"5.5.5.5\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.1.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ]
+}

tests/topotests/bfd-isis-topo1/rt1/step1/show_ipv6_route.ref

@@ -0,0 +1,70 @@
+{
+  "::ffff:202:202\/128":[
+    {
+      "prefix":"::ffff:202:202\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:303:303\/128":[
+    {
+      "prefix":"::ffff:303:303\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:404:404\/128":[
+    {
+      "prefix":"::ffff:404:404\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:505:505\/128":[
+    {
+      "prefix":"::ffff:505:505\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ]
+}

tests/topotests/bfd-isis-topo1/rt1/step2/show_bfd_peers.ref

@@ -0,0 +1,16 @@
+[
+  {
+    "peer": "10.0.2.2",
+    "interface": "eth-rt3",
+    "status": "up",
+    "diagnostic": "ok",
+    "remote-diagnostic": "ok"
+  },
+  {
+    "peer": "10.0.1.2",
+    "interface": "eth-rt2",
+    "status": "up",
+    "diagnostic": "ok",
+    "remote-diagnostic": "ok"
+  }
+]

tests/topotests/bfd-isis-topo1/rt1/step3/show_bfd_peers_healthy.ref

@@ -0,0 +1,16 @@
+[
+  {
+    "peer": "10.0.2.2",
+    "interface": "eth-rt3",
+    "status": "up",
+    "diagnostic": "ok",
+    "remote-diagnostic": "ok"
+  },
+  {
+    "peer": "10.0.1.2",
+    "interface": "eth-rt2",
+    "status": "up",
+    "diagnostic": "ok",
+    "remote-diagnostic": "ok"
+  }
+]

tests/topotests/bfd-isis-topo1/rt1/step3/show_bfd_peers_rt2_down.ref

@@ -0,0 +1,9 @@
+[
+  {
+    "peer": "10.0.2.2",
+    "interface": "eth-rt3",
+    "status": "up",
+    "diagnostic": "ok",
+    "remote-diagnostic": "ok"
+  }
+]

tests/topotests/bfd-isis-topo1/rt1/step3/show_bfd_peers_rt3_down.ref

@@ -0,0 +1,9 @@
+[
+  {
+    "peer": "10.0.1.2",
+    "interface": "eth-rt2",
+    "status": "up",
+    "diagnostic": "ok",
+    "remote-diagnostic": "ok"
+  }
+]

tests/topotests/bfd-isis-topo1/rt1/step3/show_ip_route_healthy.ref

@@ -0,0 +1,74 @@
+{
+  "2.2.2.2\/32":[
+    {
+      "prefix":"2.2.2.2\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.1.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "3.3.3.3\/32":[
+    {
+      "prefix":"3.3.3.3\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.2.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "4.4.4.4\/32":[
+    {
+      "prefix":"4.4.4.4\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.2.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "5.5.5.5\/32":[
+    {
+      "prefix":"5.5.5.5\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.1.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ]
+}

tests/topotests/bfd-isis-topo1/rt1/step3/show_ip_route_rt2_down.ref

@@ -0,0 +1,74 @@
+{
+  "2.2.2.2\/32":[
+    {
+      "prefix":"2.2.2.2\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.2.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "3.3.3.3\/32":[
+    {
+      "prefix":"3.3.3.3\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.2.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "4.4.4.4\/32":[
+    {
+      "prefix":"4.4.4.4\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.2.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "5.5.5.5\/32":[
+    {
+      "prefix":"5.5.5.5\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.2.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ]
+}

tests/topotests/bfd-isis-topo1/rt1/step3/show_ip_route_rt3_down.ref

@@ -0,0 +1,74 @@
+{
+  "2.2.2.2\/32":[
+    {
+      "prefix":"2.2.2.2\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.1.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "3.3.3.3\/32":[
+    {
+      "prefix":"3.3.3.3\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.1.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "4.4.4.4\/32":[
+    {
+      "prefix":"4.4.4.4\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.1.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "5.5.5.5\/32":[
+    {
+      "prefix":"5.5.5.5\/32",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "ip":"10.0.1.2",
+          "afi":"ipv4",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ]
+}

tests/topotests/bfd-isis-topo1/rt1/step3/show_ipv6_route_healthy.ref

@@ -0,0 +1,70 @@
+{
+  "::ffff:202:202\/128":[
+    {
+      "prefix":"::ffff:202:202\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:303:303\/128":[
+    {
+      "prefix":"::ffff:303:303\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:404:404\/128":[
+    {
+      "prefix":"::ffff:404:404\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:505:505\/128":[
+    {
+      "prefix":"::ffff:505:505\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ]
+}

tests/topotests/bfd-isis-topo1/rt1/step3/show_ipv6_route_rt2_down.ref

@@ -0,0 +1,70 @@
+{
+  "::ffff:202:202\/128":[
+    {
+      "prefix":"::ffff:202:202\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:303:303\/128":[
+    {
+      "prefix":"::ffff:303:303\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:404:404\/128":[
+    {
+      "prefix":"::ffff:404:404\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:505:505\/128":[
+    {
+      "prefix":"::ffff:505:505\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt3",
+          "active":true
+        }
+      ]
+    }
+  ]
+}

tests/topotests/bfd-isis-topo1/rt1/step3/show_ipv6_route_rt3_down.ref

@@ -0,0 +1,70 @@
+{
+  "::ffff:202:202\/128":[
+    {
+      "prefix":"::ffff:202:202\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:303:303\/128":[
+    {
+      "prefix":"::ffff:303:303\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:404:404\/128":[
+    {
+      "prefix":"::ffff:404:404\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ],
+  "::ffff:505:505\/128":[
+    {
+      "prefix":"::ffff:505:505\/128",
+      "protocol":"isis",
+      "selected":true,
+      "destSelected":true,
+      "installed":true,
+      "nexthops":[
+        {
+          "fib":true,
+          "afi":"ipv6",
+          "interfaceName":"eth-rt2",
+          "active":true
+        }
+      ]
+    }
+  ]
+}

tests/topotests/bfd-isis-topo1/rt1/zebra.conf

@@ -0,0 +1,25 @@
+log file zebra.log
+log timestamp precision 3
+!
+hostname rt1
+!
+debug zebra kernel
+debug zebra packet
+debug zebra events
+debug zebra rib
+!
+interface lo
+ ip address 1.1.1.1/32
+ ipv6 address ::ffff:0101:0101/128
+!
+interface eth-rt2
+ ip address 10.0.1.1/24
+!
+interface eth-rt3
+ ip address 10.0.2.1/24
+!
+ip forwarding
+ipv6 forwarding
+!
+line vty
+!

tests/topotests/bfd-isis-topo1/rt2/bfdd.conf

@@ -0,0 +1,12 @@
+!
+debug bfd network
+debug bfd peer
+debug bfd zebra
+!
+bfd
+ peer 10.0.1.1 interface eth-rt1
+  detect-multiplier 3
+  receive-interval 300
+  transmit-interval 300
+ !
+!

tests/topotests/bfd-isis-topo1/rt2/isisd.conf

@@ -0,0 +1,30 @@
+log file isisd.log
+!
+hostname rt2
+!
+password 1
+!
+debug isis events
+debug isis route-events
+debug isis spf-events
+!
+interface lo
+ ip router isis 1
+ ipv6 router isis 1
+ isis passive
+!
+interface eth-rt1
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+ isis bfd
+!
+interface eth-rt5
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+!
+router isis 1
+ net 49.0000.0000.0000.0002.00
+ is-type level-1
+!

tests/topotests/bfd-isis-topo1/rt2/step2/show_bfd_peers.ref

@@ -0,0 +1,9 @@
+[
+  {
+    "peer": "10.0.1.1",
+    "interface": "eth-rt1",
+    "status": "up",
+    "diagnostic": "ok",
+    "remote-diagnostic": "ok"
+  }
+]

tests/topotests/bfd-isis-topo1/rt2/zebra.conf

@@ -0,0 +1,22 @@
+log file zebra.log
+!
+hostname rt2
+!
+debug zebra kernel
+debug zebra packet
+!
+interface lo
+ ip address 2.2.2.2/32
+ ipv6 address ::ffff:0202:0202/128
+!
+interface eth-rt1
+ ip address 10.0.1.2/24
+!
+interface eth-rt5
+ ip address 10.0.3.1/24
+!
+ip forwarding
+ipv6 forwarding
+!
+line vty
+!

tests/topotests/bfd-isis-topo1/rt3/bfdd.conf

@@ -0,0 +1,12 @@
+!
+debug bfd network
+debug bfd peer
+debug bfd zebra
+!
+bfd
+ peer 10.0.2.1 interface eth-rt1
+  detect-multiplier 3
+  receive-interval 300
+  transmit-interval 300
+ !
+!

tests/topotests/bfd-isis-topo1/rt3/isisd.conf

@@ -0,0 +1,32 @@
+log file isisd.log
+!
+hostname rt3
+!
+password 1
+!
+debug isis events
+debug isis route-events
+debug isis spf-events
+!
+interface lo
+ ip router isis 1
+ ipv6 router isis 1
+ isis passive
+!
+interface eth-rt1
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+ isis network point-to-point
+ isis bfd
+!
+interface eth-rt4
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+!
+router isis 1
+ net 49.0000.0000.0000.0003.00
+ is-type level-1
+!
+

tests/topotests/bfd-isis-topo1/rt3/step2/show_bfd_peers.ref

@@ -0,0 +1,9 @@
+[
+  {
+    "peer": "10.0.2.1",
+    "interface": "eth-rt1",
+    "status": "up",
+    "diagnostic": "ok",
+    "remote-diagnostic": "ok"
+  }
+]

tests/topotests/bfd-isis-topo1/rt3/zebra.conf

@@ -0,0 +1,22 @@
+log file zebra.log
+!
+hostname rt3
+!
+debug zebra kernel
+debug zebra packet
+!
+interface lo
+ ip address 3.3.3.3/32
+ ipv6 address ::ffff:0303:0303/128
+!
+interface eth-rt1
+ ip address 10.0.2.2/24
+!
+interface eth-rt4
+ ip address 10.0.4.1/24
+!
+ip forwarding
+ipv6 forwarding
+!
+line vty
+!

tests/topotests/bfd-isis-topo1/rt4/bfdd.conf

@@ -0,0 +1,5 @@
+!
+debug bfd network
+debug bfd peer
+debug bfd zebra
+!

tests/topotests/bfd-isis-topo1/rt4/isisd.conf

@@ -0,0 +1,29 @@
+log file isisd.log
+!
+hostname rt4
+!
+password 1
+!
+debug isis events
+debug isis route-events
+debug isis spf-events
+!
+interface lo
+ ip router isis 1
+ ipv6 router isis 1
+ isis passive
+!
+interface eth-rt3
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+!
+interface eth-rt5
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+!
+router isis 1
+ net 49.0000.0000.0000.0004.00
+ is-type level-1
+!

tests/topotests/bfd-isis-topo1/rt4/zebra.conf

@@ -0,0 +1,22 @@
+log file zebra.log
+!
+hostname rt4
+!
+debug zebra kernel
+debug zebra packet
+!
+interface lo
+ ip address 4.4.4.4/32
+ ipv6 address ::ffff:0404:0404/128
+!
+interface eth-rt3
+ ip address 10.0.4.2/24
+!
+interface eth-rt5
+ ip address 10.0.5.1/24
+!
+ip forwarding
+ipv6 forwarding
+!
+line vty
+!

tests/topotests/bfd-isis-topo1/rt5/bfdd.conf

@@ -0,0 +1,5 @@
+!
+debug bfd network
+debug bfd peer
+debug bfd zebra
+!

tests/topotests/bfd-isis-topo1/rt5/isisd.conf

@@ -0,0 +1,29 @@
+log file isisd.log
+!
+hostname rt5
+!
+password 1
+!
+debug isis events
+debug isis route-events
+debug isis spf-events
+!
+interface lo
+ ip router isis 1
+ ipv6 router isis 1
+ isis passive
+!
+interface eth-rt2
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+!
+interface eth-rt4
+ ip router isis 1
+ ipv6 router isis 1
+ isis hello-multiplier 3
+!
+router isis 1
+ net 49.0000.0000.0000.0005.00
+ is-type level-1
+!

tests/topotests/bfd-isis-topo1/rt5/zebra.conf

@@ -0,0 +1,22 @@
+log file zebra.log
+!
+hostname rt5
+!
+debug zebra kernel
+debug zebra packet
+!
+interface lo
+ ip address 5.5.5.5/32
+ ipv6 address ::ffff:0505:0505/128
+!
+interface eth-rt2
+ ip address 10.0.3.2/24
+!
+interface eth-rt4
+ ip address 10.0.5.2/24
+!
+ip forwarding
+ipv6 forwarding
+!
+line vty
+!

tests/topotests/bfd-isis-topo1/test_bfd_isis_topo1.py

@@ -0,0 +1,304 @@
+#!/usr/bin/env python
+
+#
+# test_bfd_isis_topo1.py
+# Part of NetDEF Topology Tests
+#
+# Copyright (c) 2020 by
+# Network Device Education Foundation, Inc. ("NetDEF")
+#
+# Permission to use, copy, modify, and/or distribute this software
+# for any purpose with or without fee is hereby granted, provided
+# that the above copyright notice and this permission notice appear
+# in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND NETDEF DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NETDEF BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+# OF THIS SOFTWARE.
+#
+
+"""
+test_bfd_isis_topo1.py:
+
+                        +---------+
+                        |         |
+           eth-rt2 (.1) |   RT1   | eth-rt3 (.1)
+             +----------+ 1.1.1.1 +----------+
+             |          |         |          |
+             |          +---------+          |
+             |                               |
+             |                   10.0.2.0/24 |
+             |                               |
+             |                       eth-rt1 | (.2)
+             | 10.0.1.0/24              +----+----+
+             |                          |         |
+             |                          |   RT3   |
+             |                          | 3.3.3.3 |
+             |                          |         |
+        (.2) | eth-rt1                  +----+----+
+        +----+----+                  eth-rt4 | (.1)
+        |         |                          |
+        |   RT2   |                          |
+        | 2.2.2.2 |              10.0.4.0/24 |
+        |         |                          |
+        +----+----+                          |
+        (.1) | eth-rt5               eth-rt3 | (.2)
+             |                          +----+----+
+             |                          |         |
+             |                          |   RT4   |
+             |                          | 4.4.4.4 |
+             |                          |         |
+             |                          +----+----+
+             | 10.0.3.0/24           eth-rt5 | (.1)
+             |                               |
+             |                               |
+             |                   10.0.5.0/24 |
+             |                               |
+             |          +---------+          |
+             |          |         |          |
+             +----------+   RT5   +----------+
+           eth-rt2 (.2) | 5.5.5.5 | eth-rt4 (.2)
+                        |         |
+                        +---------+
+
+"""
+
+import os
+import sys
+import pytest
+import json
+import re
+from time import sleep
+from time import time
+from functools import partial
+
+# Save the Current Working Directory to find configuration files.
+CWD = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(CWD, "../"))
+
+# pylint: disable=C0413
+# Import topogen and topotest helpers
+from lib import topotest
+from lib.topogen import Topogen, TopoRouter, get_topogen
+from lib.topolog import logger
+
+# Required to instantiate the topology builder class.
+from mininet.topo import Topo
+
+
+class TemplateTopo(Topo):
+    "Test topology builder"
+
+    def build(self, *_args, **_opts):
+        "Build function"
+        tgen = get_topogen(self)
+
+        #
+        # Define FRR Routers
+        #
+        for router in ["rt1", "rt2", "rt3", "rt4", "rt5"]:
+            tgen.add_router(router)
+
+        #
+        # Define connections
+        #
+        switch = tgen.add_switch("s1")
+        switch.add_link(tgen.gears["rt1"], nodeif="eth-rt2")
+        switch.add_link(tgen.gears["rt2"], nodeif="eth-rt1")
+
+        switch = tgen.add_switch("s2")
+        switch.add_link(tgen.gears["rt1"], nodeif="eth-rt3")
+        switch.add_link(tgen.gears["rt3"], nodeif="eth-rt1")
+
+        switch = tgen.add_switch("s3")
+        switch.add_link(tgen.gears["rt2"], nodeif="eth-rt5")
+        switch.add_link(tgen.gears["rt5"], nodeif="eth-rt2")
+
+        switch = tgen.add_switch("s4")
+        switch.add_link(tgen.gears["rt3"], nodeif="eth-rt4")
+        switch.add_link(tgen.gears["rt4"], nodeif="eth-rt3")
+
+        switch = tgen.add_switch("s5")
+        switch.add_link(tgen.gears["rt4"], nodeif="eth-rt5")
+        switch.add_link(tgen.gears["rt5"], nodeif="eth-rt4")
+
+
+def setup_module(mod):
+    "Sets up the pytest environment"
+    tgen = Topogen(TemplateTopo, mod.__name__)
+    tgen.start_topology()
+
+    router_list = tgen.routers()
+
+    # For all registered routers, load the zebra configuration file
+    for rname, router in router_list.iteritems():
+        router.load_config(
+            TopoRouter.RD_ZEBRA, os.path.join(CWD, "{}/zebra.conf".format(rname))
+        )
+        router.load_config(
+            TopoRouter.RD_BFD, os.path.join(CWD, "{}/bfdd.conf".format(rname))
+        )
+        router.load_config(
+            TopoRouter.RD_ISIS, os.path.join(CWD, "{}/isisd.conf".format(rname))
+        )
+
+    tgen.start_router()
+
+
+def teardown_module(mod):
+    "Teardown the pytest environment"
+    tgen = get_topogen()
+
+    # This function tears down the whole topology.
+    tgen.stop_topology()
+
+
+def print_cmd_result(rname, command):
+    print(get_topogen().gears[rname].vtysh_cmd(command, isjson=False))
+
+
+def router_compare_json_output(rname, command, reference, count=120, wait=0.5):
+    "Compare router JSON output"
+
+    logger.info('Comparing router "%s" "%s" output', rname, command)
+
+    tgen = get_topogen()
+    filename = "{}/{}/{}".format(CWD, rname, reference)
+    expected = json.loads(open(filename).read())
+
+    # Run test function until we get an result. Wait at most 60 seconds.
+    test_func = partial(topotest.router_json_cmp, tgen.gears[rname], command, expected)
+    _, diff = topotest.run_and_expect(test_func, None, count=count, wait=wait)
+    assertmsg = '"{}" JSON output mismatches the expected result'.format(rname)
+    assert diff is None, assertmsg
+
+
+## TEST STEPS
+
+
+def test_rib_isis_step1():
+    logger.info("Test (step 1): verify RIB (IPv4 and IPv6) for IS-IS")
+    tgen = get_topogen()
+
+    # Skip if previous fatal error condition is raised
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    router_compare_json_output(
+        "rt1", "show ip route isis json", "step1/show_ip_route.ref"
+    )
+    router_compare_json_output(
+        "rt1", "show ipv6 route isis json", "step1/show_ipv6_route.ref"
+    )
+
+
+def test_bfd_isis_sessions_step2():
+    logger.info("Test (step 2): verify BFD peers for IS-IS")
+    tgen = get_topogen()
+
+    # Skip if previous fatal error condition is raised
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    # BFD is just used on three routers
+    for rt in ["rt1", "rt2", "rt3"]:
+        router_compare_json_output(
+            rt, "show bfd peers json", "step2/show_bfd_peers.ref"
+        )
+
+
+def test_bfd_isis_interface_failure_rt2_step3():
+    logger.info("Test (step 2): check failover handling when RT2 goes down")
+    tgen = get_topogen()
+
+    # Skip if previous fatal error condition is raised
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    # Let's kill the interface on rt2 and see what happens with the RIB and BFD on rt1
+    tgen.gears["rt2"].link_enable("eth-rt1", enabled=False)
+
+    # By default BFD provides a recovery time of 900ms plus jitter, so let's wait
+    # initial 2 seconds to let the CI not suffer.
+    # TODO: add check for array size
+    sleep(2)
+    router_compare_json_output(
+        "rt1", "show ip route isis json", "step3/show_ip_route_rt2_down.ref", 1, 0
+    )
+    router_compare_json_output(
+        "rt1", "show ipv6 route isis json", "step3/show_ipv6_route_rt2_down.ref", 1, 0
+    )
+    router_compare_json_output(
+        "rt1", "show bfd peers json", "step3/show_bfd_peers_rt2_down.ref", 1, 0
+    )
+
+    # Check recovery, this can take some time
+    tgen.gears["rt2"].link_enable("eth-rt1", enabled=True)
+
+    router_compare_json_output(
+        "rt1", "show ip route isis json", "step3/show_ip_route_healthy.ref"
+    )
+    router_compare_json_output(
+        "rt1", "show ipv6 route isis json", "step3/show_ipv6_route_healthy.ref"
+    )
+    router_compare_json_output(
+        "rt1", "show bfd peers json", "step3/show_bfd_peers_healthy.ref"
+    )
+
+
+def test_bfd_isis_interface_failure_rt3_step3():
+    logger.info("Test (step 2): check failover handling when RT2 goes down")
+    tgen = get_topogen()
+
+    # Skip if previous fatal error condition is raised
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    # Let's kill the interface on rt3 and see what happens with the RIB and BFD on rt1
+    tgen.gears["rt3"].link_enable("eth-rt1", enabled=False)
+
+    # By default BFD provides a recovery time of 900ms plus jitter, so let's wait
+    # initial 2 seconds to let the CI not suffer.
+    # TODO: add check for array size
+    sleep(2)
+    router_compare_json_output(
+        "rt1", "show ip route isis json", "step3/show_ip_route_rt3_down.ref", 1, 0
+    )
+    router_compare_json_output(
+        "rt1", "show ipv6 route isis json", "step3/show_ipv6_route_rt3_down.ref", 1, 0
+    )
+    router_compare_json_output(
+        "rt1", "show bfd peers json", "step3/show_bfd_peers_rt3_down.ref", 1, 0
+    )
+
+    # Check recovery, this can take some time
+    tgen.gears["rt3"].link_enable("eth-rt1", enabled=True)
+
+    router_compare_json_output(
+        "rt1", "show ip route isis json", "step3/show_ip_route_healthy.ref"
+    )
+    router_compare_json_output(
+        "rt1", "show ipv6 route isis json", "step3/show_ipv6_route_healthy.ref"
+    )
+    router_compare_json_output(
+        "rt1", "show bfd peers json", "step3/show_bfd_peers_healthy.ref"
+    )
+
+
+def test_memory_leak():
+    "Run the memory leak test and report results."
+    tgen = get_topogen()
+    if not tgen.is_memleak_enabled():
+        pytest.skip("Memory leak test/report is disabled")
+
+    tgen.report_memory_leaks()
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))