昨天，碰到一個dhcp client renew ip 的時候，網關無法配置成功的問題。目前仍舊沒有思路。在此做一個筆記，順便理一理思路。
1, renew 的時候，request的是同一個ip，通常網關是不變的，此時。若發現網關未變化，不需要刪除default route , then add default again. so, need judge weather the default is changed. we can set a flag.
2. another case: when dhcp client perform renew, dhcp client get a new ip, but the default route does not change, but this time, kernel will delete default route, we should add default again when we process dhcp option.
3. but judge ip is change or default route is change , are in two file. how to define a flag can be modified in this 2 files ? share memory ?
4. if is in share memory, what time to reset the flag, we should make sure, everytime perform renew. we can consider everytime we receive an dhcp-ack.
today we do intergrate test with cwp, we found iptables didn't work. we should consider.
and new event is define, we should modify code to fix it.
