ACL访问控制列表
ip route 0.0.0.0 0.0.0.0 172.16.3.1
exit
ip route 172.16.1.0 255.255.255.0 172.16.2.1
ip route 172.16.4.0 255.255.255.0 172.16.3.2
access-list 100 permit tcp host 172.16.1.2 host 172.16.4.2 eq www
access-list 100 deny icmp host 172.16.1.2 host 172.16.4.2 echo
int s2/0
ip access-group 100 out