The advent of the modern data center revolutionized just about everything we know about computing and networking. Whether it be the rise of NoSQL databases, new application architectures and microservices, or Clos networks with routing as the fundamental rubric rather than bridging, they have each upended hitherto well-regarded ideas. This also has affected how services such as firewalls and load balancers are deployed.
This chapter examines how the new model of services shifts routing all the way to the server, and how we configure BGP on the host to communicate with the ToR or leaf switch.
Traditional network administrators’ jurisdiction ended at the ToR switch. Server administrators handled server configuration and management. In the new-world order, either separate server and network administrators have been replaced by a single all-around data center operator, or network administrators must work in conjunction with server administrators to configure routing on hosts, as well. In either case, it is important for a data center operator to ensure that the configuration of BGP on the host does not compromise the integrity of the network.
In traditional data center networks, the boundary between bridging and routing, the L2–L3 gateway, was where services such as firewall and load balancers were deployed. The boundary was a natural fit because the boundary represented in some sense the separation of the client from the server. ...