问debian 9.0双网卡配置双IP？

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo

valid_lft forever preferred_lft foreve

inet6 ::1/128 scope host

valid_lft forever preferred_lft foreve

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

link/ether 52:54:00:3c:f0:e1 brd ff:ff:ff:ff:ff:ff

inet 172.16.16.11/20 brd 172.16.31.255 scope global eth0

valid_lft forever preferred_lft foreve

inet6 fe80::5054:ff:fe3c:f0e1/64 scope link

valid_lft forever preferred_lft foreve

3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

link/ether 20:90:6f:61:94:58 brd ff:ff:ff:ff:ff:ff

inet 172.16.16.9/20 brd 172.16.31.255 scope global eth1

valid_lft forever preferred_lft foreve

inet6 fe80::2290:6fff:fe61:9458/64 scope link

valid_lft forever preferred_lft foreve

现在2个公网IP 都是通的，但是172.16.16.11的公网能进入服务器，172.16.16.9的公网就不能进入服务器.请问怎么样 2个都可以进入服务器?