5. Switch aggregation

Our host continues to grow. It is multiplying its VMware hosts, forcing it to deploy several physical switches to ensure the necessary connectivity. What's more, for obvious reasons of operational reliability, it now has a nominal architecture in one building and a backup architecture in another.

Each building has several interconnected switches. To avoid Level 2 loop problems (at Ethernet level), it is necessary to implement an additional protocol between the switches, called "Spanning Tree".

In simplified terms, if several switches are connected to each other and exchange information on the Ethernet addresses they host, it's a safe bet that at some point, for a given address, the path will not be deterministic and will introduce a loop at level 2 that will circulate the Ethernet packet at maximum speed, saturating the network.