BGP Control Plane Overhead in Fat-Trees: An Analytical Approach

State-of-the-art Data Center Networks (DCNs) adopt fat-tree topologies based on the original Clos networks due to their non-blocking and constant bisection bandwidth characteristics. Massive Scale Data Center networks comprise thousands of switches, and demand deploying a routing protocol to build Equal Cost Multi-Path connectivity among end nodes. Routing protocol overhead is one of the foremost important parameters to consider in DCN design. Existing approaches to measuring this overhead are based on large emulations or simulations that capture the packets exchanged under certain scenarios and then process them to obtain this measurement. This requires a lot of development effort and may not always be possible at large scales. In this work, using an analytical approach, we analyze the control plane overhead for BGP in the data center. Our proposal manages to measure the overhead injected by BGP in failure and recovery scenarios without the need to develop and deploy large emulations or simulations. The main idea is to use an analytical methodology to obtain mathematical formulas from the expected behavior of BGP. The results show that it is possible to adequately model the load injected by BGP under a set of failure and recovery scenarios. The validation was performed in a simulated environment over the ns-3 simulator.