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zebra: Allow kernel routes to stick around better on interface state …
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…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>
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@donaldsharp
donaldsharp committed Jun 23, 2022
1 parent 3689905 commit fc3de98
Showing 1 changed file with 11 additions and 16 deletions.
27 changes: 11 additions & 16 deletions zebra/zebra_nhg.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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) {
Expand Down

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