Lattice security model: A security model that defines access to resources based on a lattice-like structure of security levels and clearance rules. It is used to enforce hierarchical access control and prevent unauthorized access to sensitive information. Examples of the lattice security model include the Bell-LaPadula and Biba models.

Layer 2 switches: Network devices that operate at the data link layer (Layer 2) of the Open Systems Interconnection (OSI) model. They are responsible for forwarding data frames between devices on a local network based on the device's MAC addresses. Layer 2 switches are central to local network operation and performance, but they must be properly configured and managed to prevent potential security issues such as MAC flooding or spoofing attacks.

Layer 2 Tunneling Protocol (L2TP): A protocol used to support virtual private networks (VPNs), which provides a private, secure path for data transmission across a public network such as the internet. L2TP creates a tunnel between two L2TP connection points and encapsulates data sent between them. While L2TP itself doesn't provide encryption, it's often used in conjunction with the IPsec protocol, which does provide encryption, to create a more secure VPN.

Layer 3 and 4 Switches: Devices that operate at both the network (Layer 3) and transport (Layer 4) layers of the OSI model. They combine the fast-switching capabilities of a Layer 2 switch with the routing capabilities of a router (Layer 3) and can also make forwarding decisions based on transport layer information (Layer 4), such as TCP or UDP port numbers. This allows for more granular control of network traffic, which can be beneficial for both network performance and security. For example, Layer 4 switching can be used to help mitigate DoS attacks by limiting traffic to certain ports.

Layer 4-7 Switches: Also known as content switches, these devices operate at the transport layer (Layer 4) and higher layers (up to Layer 7 – the application layer) of the OSI model. They not only manage network traffic based on IP addresses and port numbers but also on the basis of data content. This enables more complex and flexible network management, including load balancing and quality of service features, as well as advanced security features, such as protection against application-specific attacks.

Layered security: A security strategy that uses multiple layers of defense to protect against attacks and prevent unauthorized access. It is used to reduce the risk of a single point of failure and increase the overall security of a system. Examples of layered security include firewalls, intrusion detection systems, and access control policies.