|  | 1.3 | LAN Design
| 1.3.4 | Developing a LAN topology

After the requirements for the overall network have been gathered, an overall topology or model of the LAN can be developed. The major pieces of this topology design can be broken into three unique categories of the OSI model. Layer 1 - Physical Layer Includes wire media type such as CAT5 UTP and fiber-optic cable along with TIA/EIA-568-A Standard for layout and connection of wiring schemes. Design Goal Build this layer of the OSI model with speed and expansion capabilities. Layer 2 - Data Link Layer Includes selection of Layer 2 devices such as bridges or LAN switches used to interconnect the Layer 1 media to a LAN segment. Devices at this layer will determine the size of the collision and broadcast domains. Design Goals Create a concentration point within the MDFs or IDFs where end hosts can be grouped at Layer 1 to form a physical LAN segment. Install LAN switching devices that use microsegmentation in order to reduce the collision domain size. Create a point (at Layer 2) of the topology where users can be grouped into virtual workgroups (VLANs) and unique broadcast domains. Layer 3 - Network Layer Includes selection of Layer 3 devices such as routers that are used to create unique LAN segments and allow communication between segments based on Layer 3 addressing such as IP addressing. Design Goals Build a path between LAN segments that will filter the flow of data packets. Isolate ARP broadcasts. Isolation of collisions between segments. Filtering of Layer 4 services between segments.