zebra: Allow kernel routes to stick around better on interface state changes

Currently kernel routes on system bring up would be `auto-accepted`,
then if an interface went down all kernel and system routes would
be re-evaluated.  There exists situations where a kernel route can
exist but the interface itself is not exactly in a state that is
ready to create a connected route yet.  As such when any interface
goes down in the system all kernel/system routes would be re-evaluated
and then since that interfaces connected route is not in the table yet
the route is matching against a default route( or not at all ) and
is being dropped.

Modify the code such that kernel or system routes just look for interface
being in a good state (up or operative) and accept it.

Broken code:
eva# show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
       F - PBR, f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
       t - trapped, o - offload failure

K>* 0.0.0.0/0 [0/100] via 192.168.119.1, enp39s0, 00:05:08
K>* 1.2.3.5/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.6/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.7/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.8/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.9/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.10/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.11/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.12/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.13/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.14/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.16/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 1.2.3.17/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
C>* 4.5.6.99/32 is directly connected, dummy9, 00:05:08
K>* 4.9.10.11/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:05:08
K>* 10.11.12.13/32 [0/0] via 192.168.119.1, enp39s0, 00:05:08
C>* 192.168.10.0/24 is directly connected, dummy99, 00:05:08
C>* 192.168.119.0/24 is directly connected, enp39s0, 00:05:08
<shutdown a non-related interface>
eva# show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
       F - PBR, f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
       t - trapped, o - offload failure

K>* 0.0.0.0/0 [0/100] via 192.168.119.1, enp39s0, 00:05:28
C>* 4.5.6.99/32 is directly connected, dummy9, 00:05:28
K>* 10.11.12.13/32 [0/0] via 192.168.119.1, enp39s0, 00:05:28
C>* 192.168.10.0/24 is directly connected, dummy99, 00:05:28
C>* 192.168.119.0/24 is directly connected, enp39s0, 00:05:28

Working code:
eva# show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
       F - PBR, f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
       t - trapped, o - offload failure

K>* 0.0.0.0/0 [0/100] via 192.168.119.1, enp39s0, 00:00:04
K>* 1.2.3.5/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.6/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.7/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.8/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.9/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.10/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.11/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.12/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.13/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.14/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.16/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 1.2.3.17/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
C>* 4.5.6.99/32 is directly connected, dummy9, 00:00:04
K>* 4.9.10.11/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:04
K>* 10.11.12.13/32 [0/0] via 192.168.119.1, enp39s0, 00:00:04
C>* 192.168.10.0/24 is directly connected, dummy99, 00:00:04
C>* 192.168.119.0/24 is directly connected, enp39s0, 00:00:04
<shutdown a non-related interface>
eva# show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
       F - PBR, f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
       t - trapped, o - offload failure

K>* 0.0.0.0/0 [0/100] via 192.168.119.1, enp39s0, 00:00:15
K>* 1.2.3.5/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.6/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.7/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.8/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.9/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.10/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.11/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.12/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.13/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.14/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.16/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 1.2.3.17/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
C>* 4.5.6.99/32 is directly connected, dummy9, 00:00:15
K>* 4.9.10.11/32 [0/0] via 172.22.0.44, br-23e378ed7fd2 linkdown, 00:00:15
K>* 10.11.12.13/32 [0/0] via 192.168.119.1, enp39s0, 00:00:15
C>* 192.168.10.0/24 is directly connected, dummy99, 00:00:15
C>* 192.168.119.0/24 is directly connected, enp39s0, 00:00:15
eva#

Signed-off-by: Donald Sharp <sharpd@nvidia.com>

diff --git a/zebra/zebra_nhg.c b/zebra/zebra_nhg.c
index f025507f7d1edefa9380582c1b3ebd23879f5525..9a0f48158f036959285eb5382171bf67b9495b40 100644 (file)
--- a/zebra/zebra_nhg.c
+++ b/zebra/zebra_nhg.c
@@ -2084,11 +2084,7 @@ static int nexthop_active(struct nexthop *nexthop, struct nhg_hash_entry *nhe,
                 * route and interface is up, its active. We trust kernel routes
                 * to be good.
                 */
-               if (ifp
-                   && (if_is_operative(ifp)
-                       || (if_is_up(ifp)
-                           && (type == ZEBRA_ROUTE_KERNEL
-                               || type == ZEBRA_ROUTE_SYSTEM))))
+               if (ifp && (if_is_operative(ifp)))
                        return 1;
                else
                        return 0;
@@ -2457,20 +2453,19 @@ static unsigned nexthop_active_check(struct route_node *rn,
                zlog_debug("%s: re %p, nexthop %pNHv", __func__, re, nexthop);
 
        /*
-        * If the kernel has sent us a NEW route, then
+        * If this is a kernel route, then if the interface is *up* then
         * by golly gee whiz it's a good route.
-        *
-        * If its an already INSTALLED route we have already handled, then the
-        * kernel route's nexthop might have became unreachable
-        * and we have to handle that.
         */
-       if (!CHECK_FLAG(re->status, ROUTE_ENTRY_INSTALLED) &&
-           (re->type == ZEBRA_ROUTE_KERNEL ||
-            re->type == ZEBRA_ROUTE_SYSTEM)) {
-               SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
-               goto skip_check;
-       }
+       if (re->type == ZEBRA_ROUTE_KERNEL || re->type == ZEBRA_ROUTE_SYSTEM) {
+               struct interface *ifp;
+
+               ifp = if_lookup_by_index(nexthop->ifindex, nexthop->vrf_id);
 
+               if (ifp && (if_is_operative(ifp) || if_is_up(ifp))) {
+                       SET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
+                       goto skip_check;
+               }
+       }
 
        vrf_id = zvrf_id(rib_dest_vrf(rib_dest_from_rnode(rn)));
        switch (nexthop->type) {