L2 rule—A rule containing only Layer 2 (L2) matching conditions, such as Ethernet MAC address and Ethernet type.
L3 rule—A rule containing only Layer 3 (L3) matching conditions, such as source or destination IP address and protocol.
L4 rule—A rule containing both Layer 3 (L3) and Layer 4 (L4) matching conditions, such as TCP/UDP port number.