1) use sdm prefer access 分配acl条目资源。2) L2 port 只能用in方向acl3) two kinds traffic：ip/mac.4) 三种过滤应用。L3 port acl,this acl accesscontrol traffic between vlans,and apply to L3 interface.L2 port acl,this acl accesscontrol traffic entering a l2 interface.vlan acl,all traffic in the same vla