ppp not removing address when disconnected

[John Bayly]

I'm using ppp on FreeBSD 7.2-RELEASE. Got this immensely annoying issue 
that when the ADSL connection drops the IP address isn't being removed 
from the tun interface, making it look like the connection is still up.

I've tries this in interactive mode:

    Using interface: tun0
    ppp ON router> dial
    ppp ON router>
    Ppp ON router>
    PPp ON router> Warning: ff02:7::/32: Change route failed: errno:
    Network is unreachable
    PPP ON router> iface show
    tun0 (idx 7) <UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1492 has 1 address:
       inet 81.134.xx.xx --> 81.134.yy.yy netmask 0xffffffff
    PPP ON router> close
    PPp ON router> Warning: ff02:7::/32: Change route failed: errno:
    Network is unreachable
    ppp ON router>
    ppp ON router> iface show
    tun0 (idx 7) <POINTOPOINT,RUNNING,MULTICAST> mtu 1500 has 1 address:
       inet 81.134.xx.xx --> 81.134.yy.yy netmask 0xffffffff
    ppp ON router> iface clear
    ppp ON router> iface show
    tun0 (idx 7) <POINTOPOINT,RUNNING,MULTICAST> mtu 1500 has 0 addresses:
    ppp ON router>

As you can see, the interface comes up with an address when I dial, 
however when I close the connection, the interface still shows the 
address, it's only when I call "iface clear" that the address is removed.

I added "iface clear" to my /etc/ppp/ppp.linkdown, but it makes no 
difference. This is because ppp is still in OPENED state (as per the man 
page: all addresses except for the NCP negotiated address are deleted 
from the interface.). I've confirmed this by turning on all logging, and 
seeing that the "iface clear" command is sent before 
"SendTerminateReq(4)" is called.

Am I missing something in /etc/ppp/ppp.conf that tells ppp to remove the 
address when a connection is down?

Many thanks,
John