请教启动是网卡为何会link state changed to DOWN!

请教启动是网卡为何会link state changed to DOWN!
这个问题令我十分困惑
现在主要是ADSL+NATD做网关启动时，NATD无法绑定tun0地址

屏幕显示：
starting ppp.
rl0: link state changed to DOWN
starting divert daemons: natdnatd: tun0: cannot get interface address

启动后可以使用ppp_nat,带客户机，但natd的映射功能就无法实现了

rc.conf内容为：
ppp_enable="YES"
ppp_mode="ddial"
ppp_profile="adsl"
ppp_nat="YES"
firewall_enable="YES"
firewall_quiet="NO"
gateway_enable="YES"
ifconfig_rl1="inet 192.168.0.100 netmask 255.255.255.0 media 100BaseTX mediaopt
natd_enable="YES"
natd_interface="tun0"
natd_flages="-dynamic"

rc.firewall内容为：
cmd="ipfw -q add"
pif=tun
ks="keep-state"
ipfw -q -f flush
$cmd 400 allow all from any to any via tun
$cmd 401 allow all from any to any via rl0
$cmd 402 allow all from any to any via rl1
$cmd 403 allow all from any to any via lo0
$cmd 500 divert natd ip from any to any via $pif

请高手教我~，不胜感激！！！