A core switch/router is generally connected to several ToR switches via aggregation switches. A wide area network (WAN) connection to the outside carrier network may be included in the core switch, which is at the top of the cloud data center network pyramid. This article looks at what each such tool does, compares how they differ from each other, and offers suggestions as to what sort of network each. Link Aggregation is a nebulous term used to describe various implementations and underlying technologies. While there are many approaches, this article. The aggregation (sometimes also called distribution) layer is a real crossroad. The primary function of an aggregation switch is to aggregate and forward data from multiple network devices, such as access.