The topology of a network is the arrangement or relationship of the network devices and the interconnections between them. LAN and WAN topologies can be viewed in two ways:
- Physical topology: Refers to the physical connections and identifies how end devices and infrastructure devices such as routers, switches, and wireless access points are interconnected. Physical topologies are usually point-to-point or star. See Figure 1.
- Logical topology: Refers to the way a network transfers frames from one node to the next. This arrangement consists of virtual connections between the nodes of a network. These logical signal paths are defined by data link layer protocols. The logical topology of point-to-point links is relatively simple while shared media offers deterministic and a non-deterministic media access control methods. See Figure 2.
The data link layer "sees" the logical topology of a network when controlling data access to the media. It is the logical topology that influences the type of network framing and media access control used.