ipv6: router reachability probing
RFC 4191 states in 3.5:
When a host avoids using any non-reachable router X and instead sends
a data packet to another router Y, and the host would have used
router X if router X were reachable, then the host SHOULD probe each
such router X's reachability by sending a single Neighbor
Solicitation to that router's address. A host MUST NOT probe a
router's reachability in the absence of useful traffic that the host
would have sent to the router if it were reachable. In any case,
these probes MUST be rate-limited to no more than one per minute per
router.
Currently, when the neighbour corresponding to a router falls into
NUD_FAILED, it's never considered again. Introduce a new rt6_nud_state
value, RT6_NUD_FAIL_PROBE, which suggests the route should not be used but
should be probed with a single NS. The probe is ratelimited by the existing
code. To better distinguish meanings of the failure values, rename
RT6_NUD_FAIL_SOFT to RT6_NUD_FAIL_DO_RR.
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 41b1ce6..4c09bd2 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -252,6 +252,7 @@
void neigh_destroy(struct neighbour *neigh);
int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb);
int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, u32 flags);
+void __neigh_set_probe_once(struct neighbour *neigh);
void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev);
int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb);