Three-Layer Networking Design

Large and medium-sized campus networks typically use the following two networking modes: stacking and dual-core networking.

• Stacking networking

  In Figure 3-4, the core layer, aggregation layer, and access layer use stacking. Eth-Trunk networking is recommended between the access layer and aggregation layer, and between the aggregation layer and core layer. The networking where stacking and Eth-Trunk are used is loop-free, and the configuration is simple. There is no need to deploy complex ring network protocols or reliability protocols (such as RSTP, MSTP, and RRPP). This networking ensures device-level and link-level reliability, simplifies the network topology, and reduces deployment and maintenance workload.

  Figure 3-4 Stacking networking

• Dual-core networking
  In Figure 3-5, the core layer uses two devices that are deployed independently, and the core layer is connected to the aggregation layer through ECMP links. It is recommended that dual devices at the aggregation layer and access layer constitute a stack. The aggregation layer and access layer are connected through Eth-Trunks. This networking also ensures high reliability and high performance of the network. In addition, the two core devices are independent of each other.

  Figure 3-5 Dual-core networking

Stacking can virtualize multiple physical switches into one logical switch, which ensures device redundancy and simplifies service configuration. However, there is only one core in terms of services. In dual-core networking, there are two core devices from the service perspective. The aggregation layer can have two equal-cost routes to the core layer. During the upgrade of core devices, services are not interrupted. To simplify O&M, stacking networking is recommended. If customers are sensitive to service interruption, dual-core networking is recommended.