Three-Tier Network Topologies

AB.

Three-tier network topology is a network architecture that consists of three layers: access, distribution, and core. Each layer serves a specific function, and together they form a hierarchical structure that provides scalability, resilience, and efficient traffic flow.

Here are two descriptions of three-tier network topologies:

A. The distribution layer runs Layer 2 and Layer 3 technologies

The distribution layer is responsible for aggregating traffic from the access layer and forwarding it to the core layer. It also provides policy-based connectivity and quality of service (QoS) functions, such as traffic filtering and prioritization. Therefore, it needs to support both Layer 2 switching and Layer 3 routing technologies. Layer 2 switching is used to forward traffic within the same subnet, while Layer 3 routing is used to forward traffic between different subnets. By supporting both technologies, the distribution layer can perform its functions effectively.

B. The network core is designed to maintain continuous connectivity when devices fail

The core layer is responsible for providing high-speed connectivity between different parts of the network. It is designed to be highly available and resilient, so it can maintain connectivity even if devices fail. This is achieved by using redundant links and devices, such as switches and routers. Therefore, the core layer should be designed with no single point of failure, so that if one device fails, traffic can be rerouted through another device without disruption. In this way, the network core ensures continuous connectivity and high availability for the entire network.

Therefore, options A and B are correct descriptions of three-tier network topologies. Option C is incorrect because the access layer typically does not manage routing between devices in different domains, but rather provides access to the network for end-user devices. Option D is also incorrect because the core layer does not maintain wired connections for each host, but rather provides high-speed connectivity between different parts of the network. Option E is also incorrect because the core and distribution layers have different functions, as described above.