IPv6 link local address missing on wwan0 interface?

[Bjørn Mork <bmork telenor net>]

Hello,

I just noticted something weird on my NM + MM managed LTE modem
interface: There is no IPv6 link local address:

root@miraculix:/etc# ip addr show dev wwan0
134: wwan0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default 
qlen 1000
    link/ether 3a:50:b3:ff:65:29 brd ff:ff:ff:ff:ff:ff
    inet 10.236.15.139/29 brd 10.236.15.143 scope global wwan0
       valid_lft forever preferred_lft forever
    inet6 2a02:2121:30a:8ec9:3850:b3ff:feff:6529/64 scope global mngtmpaddr dynamic 
       valid_lft forever preferred_lft forever
    inet6 2a02:2121:30a:8ec9:ec6f:52f7:b166:425f/64 scope global 
       valid_lft forever preferred_lft forever


As expected, the addrgenmode is set to 'none', so all address generation
is supposed to be handled by NM, isn't it?


root@miraculix:/etc# ip -d link show dev wwan0
134: wwan0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN mode DEFAULT 
group default qlen 1000
    link/ether 3a:50:b3:ff:65:29 brd ff:ff:ff:ff:ff:ff promiscuity 0 addrgenmode none numtxqueues 1 
numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 


The hardware here is an EM7455 in MBIM mode.  I am using the Debian
1.6.2-3 version of NetworkManager along with some arbitrary "1.7.0" git
checkout of ModemManager.  Let me know if you need more details.

I don't know if this could possibly cause any issues.  It was just a bit
unexpected.  I tried to ping ff02::1%wwan0 and expected at least one
link local reply.

And RFC4291 is pretty clear, quoting from section 2.1:

   All interfaces are required to have at least one Link-Local unicast
   address





Bjørn