zebra: set connected route metric based on the devaddr metric

MACVLAN devices are typically used for applications such as VRR/VRRP that
require a second MAC address (virtual). These devices have a corresponding
SVI/VLAN device -
root@TORC11:~# ip addr show vlan1002
39: vlan1002@bridge: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9152 qdisc noqueue master vrf1 state UP group default
    link/ether 00:02:00:00:00:2e brd ff:ff:ff:ff:ff:ff
    inet6 2001:aa:1::2/64 scope global
       valid_lft forever preferred_lft forever
root@TORC11:~# ip addr show vlan1002-v0
40: vlan1002-v0@vlan1002: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9152 qdisc noqueue master vrf1 state UP group default
    link/ether 00:00:5e:00:01:01 brd ff:ff:ff:ff:ff:ff
    inet6 2001:aa:1::a/64 metric 1024 scope global
       valid_lft forever preferred_lft forever
root@TORC11:~#

The macvlan device is used primarily for RX (VR-IP/VR-MAC). And TX is via
the SVI. To acheive that functionality the macvlan network's metric
is set to a higher value.

Zebra currently ignores the devaddr metric sent by the kernel and hardcodes
it to 0. This commit eliminates that hardcoding. If the devaddr metric
is available (METRIC_MAX) it is used for setting up the connected route
otherwise we fallback to the dev/interface metric.

Setting the macvlan metric to a higher value ensures that zebra will always
select the connected route on the SVI (and subsequently use it for next hop
resolution etc.) -
root@TORC11:~# vtysh -c "show ip route vrf vrf1 2001:aa:1::/64"
Routing entry for 2001:aa:1::/64
  Known via "connected", distance 0, metric 1024, vrf vrf1
  Last update 11:30:56 ago
  * directly connected, vlan1002-v0

Routing entry for 2001:aa:1::/64
  Known via "connected", distance 0, metric 0, vrf vrf1, best
  Last update 11:30:56 ago
  * directly connected, vlan1002

root@TORC11:~#

Ticket: CM-23511
Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/zebra/connected.c b/zebra/connected.c
index ab66eb3324..c449855f6d 100644
--- a/zebra/connected.c
+++ b/zebra/connected.c
@@ -209,6 +209,7 @@ void connected_up(struct interface *ifp, struct connected *ifc)
 		.ifindex = ifp->ifindex,
 		.vrf_id = ifp->vrf_id,
 	};
+	uint32_t metric;
 
 	if (!CHECK_FLAG(ifc->conf, ZEBRA_IFC_REAL))
 		return;
@@ -243,11 +244,13 @@ void connected_up(struct interface *ifp, struct connected *ifc)
 		break;
 	}
 
+	metric = (ifc->metric < (uint32_t)METRIC_MAX) ?
+				ifc->metric : ifp->metric;
 	rib_add(afi, SAFI_UNICAST, ifp->vrf_id, ZEBRA_ROUTE_CONNECT, 0, 0, &p,
-		NULL, &nh, RT_TABLE_MAIN, ifp->metric, 0, 0, 0);
+		NULL, &nh, RT_TABLE_MAIN, metric, 0, 0, 0);
 
 	rib_add(afi, SAFI_MULTICAST, ifp->vrf_id, ZEBRA_ROUTE_CONNECT, 0, 0, &p,
-		NULL, &nh, RT_TABLE_MAIN, ifp->metric, 0, 0, 0);
+		NULL, &nh, RT_TABLE_MAIN, metric, 0, 0, 0);
 
 	if (IS_ZEBRA_DEBUG_RIB_DETAILED) {
 		char buf[PREFIX_STRLEN];
@@ -276,7 +279,7 @@ void connected_up(struct interface *ifp, struct connected *ifc)
 /* Add connected IPv4 route to the interface. */
 void connected_add_ipv4(struct interface *ifp, int flags, struct in_addr *addr,
 			uint16_t prefixlen, struct in_addr *broad,
-			const char *label)
+			const char *label, uint32_t metric)
 {
 	struct prefix_ipv4 *p;
 	struct connected *ifc;
@@ -288,6 +291,7 @@ void connected_add_ipv4(struct interface *ifp, int flags, struct in_addr *addr,
 	ifc = connected_new();
 	ifc->ifp = ifp;
 	ifc->flags = flags;
+	ifc->metric = metric;
 	/* If we get a notification from the kernel,
 	 * we can safely assume the address is known to the kernel */
 	SET_FLAG(ifc->conf, ZEBRA_IFC_QUEUED);
@@ -500,7 +504,7 @@ void connected_delete_ipv4(struct interface *ifp, int flags,
 /* Add connected IPv6 route to the interface. */
 void connected_add_ipv6(struct interface *ifp, int flags, struct in6_addr *addr,
 			struct in6_addr *broad, uint16_t prefixlen,
-			const char *label)
+			const char *label, uint32_t metric)
 {
 	struct prefix_ipv6 *p;
 	struct connected *ifc;
@@ -512,6 +516,7 @@ void connected_add_ipv6(struct interface *ifp, int flags, struct in6_addr *addr,
 	ifc = connected_new();
 	ifc->ifp = ifp;
 	ifc->flags = flags;
+	ifc->metric = metric;
 	/* If we get a notification from the kernel,
 	 * we can safely assume the address is known to the kernel */
 	SET_FLAG(ifc->conf, ZEBRA_IFC_QUEUED);