SLAAC not working

[Greg Rivers]

I have a couple of hosts on different networks running 11.1-RELEASE amd64. Neither host will auto-configure its IPv6 address, even though valid router advertisements[1] are present. Both hosts have two oce(4) interfaces aggregated in fail-over mode via lagg(4). The lagg interface is configured thusly (/etc/rc.conf):

ifconfig_oce0="up"
ifconfig_oce1="up"
cloned_interfaces="lagg0"
ifconfig_lagg0="inet xxx.xxx.217.100/25 laggproto failover laggport oce0 laggport oce1"
defaultrouter="xxx.xxx.217.1"
ip6addrctl_policy="ipv6_prefer"
ifconfig_lagg0_ipv6="inet6 accept_rtadv"
rtsold_enable="YES"

The running interface looks like this:
lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
	options=507bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWFILTER,VLAN_HWTSO>
	ether ac:16:2d:1e:b8:80
	inet xxx.xxx.217.100 netmask 0xffffff80 broadcast xxx.xxx.217.127 
	inet6 fe80::ae16:2dff:fe1e:b880%lagg0 prefixlen 64 scopeid 0xc 
	nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
	media: Ethernet autoselect
	status: active
	groups: lagg 
	laggproto failover lagghash l2,l3,l4
	laggport: oce0 flags=5<MASTER,ACTIVE>
	laggport: oce1 flags=0<>

ndp(8) shows only:
Neighbor                             Linklayer Address  Netif Expire    S Flags
fe80::ae16:2dff:fe1e:b880%lagg0      ac:16:2d:1e:b8:80  lagg0 permanent R

Other hosts (running RedHat 6) on the same network SLAAC just fine. Does anyone have insight into this problem or suggestions for troubleshooting?

-- 
Greg Rivers


[1]
Internet Control Message Protocol v6
    Type: Router Advertisement (134)
    Code: 0
    Checksum: 0x8176 [correct]
    [Checksum Status: Good]
    Cur hop limit: 64
    Flags: 0x00, Prf (Default Router Preference): Medium
        0... .... = Managed address configuration: Not set
        .0.. .... = Other configuration: Not set
        ..0. .... = Home Agent: Not set
        ...0 0... = Prf (Default Router Preference): Medium (0)
        .... .0.. = Proxy: Not set
        .... ..0. = Reserved: 0
    Router lifetime (s): 1800
    Reachable time (ms): 0
    Retrans timer (ms): 0
    ICMPv6 Option (Source link-layer address : 64:a0:e7:45:63:43)
        Type: Source link-layer address (1)
        Length: 1 (8 bytes)
        Link-layer address: Cisco_45:63:43 (64:a0:e7:45:63:43)
    ICMPv6 Option (Prefix information : 26xx:xxxx:4013:23::/64)
        Type: Prefix information (3)
        Length: 4 (32 bytes)
        Prefix Length: 64
        Flag: 0xc0, On-link flag(L), Autonomous address-configuration flag(A)
            1... .... = On-link flag(L): Set
            .1.. .... = Autonomous address-configuration flag(A): Set
            ..0. .... = Router address flag(R): Not set
            ...0 0000 = Reserved: 0
        Valid Lifetime: 2592000
        Preferred Lifetime: 604800
        Reserved
        Prefix: 26xx:xxxx:4013:23::
    ICMPv6 Option (MTU : 9216)
        Type: MTU (5)
        Length: 1 (8 bytes)
        Reserved
        MTU: 9216