A Local Area Network is a network infrastructure that spans a small geographical area. LANs have specific characteristics:
- LANs interconnect end devices in a limited area such as a home, school, office building, or campus.
- A LAN is usually administered by a single organisation or individual. Administrative control is enforced at the network level and governs the security and access control policies.
- LANs provide high-speed bandwidth to internal end devices and intermediary devices, as shown in the figure.
The diagram is an illustration of a LAN. At the centre of the diagram is a switch. There are four Ethernet connections on the switch.
At the top left is a connection to a PC. Below that is a connection to the computer at the desk of a worker.
Below that is another connection to the computer at the desk of a worker. At the bottom left is a connection to an IP phone.
To the right of the switch is a connection to a server.
The text under the figure reads: a network serving a home, small building, or a small campus is considered a LAN.
WANs
The figure shows a WAN which interconnects two LANs. A WAN is a network infrastructure that spans a wide geographical area. WANs are typically managed by service providers (SPs) or Internet Service Providers (ISPs).
WANs have specific characteristics:
WANs have specific characteristics:
- WANs interconnect LANs over wide geographical areas such as between cities, states, provinces, countries, or continents.
- WANs are usually administered by multiple service providers.
- WANs typically provide slower speed links between LANs.
The figure shows two branch LANs connected via a WAN link. Both LANs are highlighted in a light yellow box and consist of a central switch connected to three PCs, an IP phone, a server, and a router. The two routers are connected via a red WAN link. On the left is the branch 1 LAN and on the right is the branch 2 LAN.
Zone-Based Policy Firewall
Common Security Architectures
Firewall design is primarily about device interfaces permitting or denying traffic based on the source, the destination, and the type of traffic. Some designs are as simple as designating an outside network and an inside network, which are determined by two interfaces on a firewall.
Here are three common firewall designs.
Here are three common firewall designs.
