In this chapter, we will use two different designs. Most designs use either a Benes or Clos leaf-spine design. For comparison, we will use the core-aggregation design.
As we discussed in earlier chapters, a leaf-spine design is the most common multi-rack PoD design. This design will be central to most of the different examples we will give.
In a core-aggregation design, multiple switches are connected to each other, necessitating using the spanning tree protocol or other methods to prevent network loops from forming. A network loop is where multiple switches send the same packets out of all their interfaces. Loops can cause broadcast storms, where devices send a massive amount of packets and receive multiple duplicate packets; this can take down the entire network.
