Load balancer with BGP and UCMP

Uniform load distribution to anycast servers using BGP bandwidth community and unequal cost multipath forwarding

Scalable modern applications are deployed as clusters of server instances and load balancers are needed to distribute client requests across server instances. In order to ensure positive user experience an application needs to be always responsive and no instance should get bogged down with overload.

Sophisticated load balancing solutions help but often involve expensive and proprietary components. These also are additional point of failure requiring maintenance and are often overkill for most use cases.

Here is one solution to this complex problem that can achieve spreading client requests evenly across application servers with network switches running Cumulus Linux. All this is achieved without adding any additional device or component.

The case in point is that the user has a large number of anycast services running in a multipod Clos network. The number of service endpoints can dynamically change and user expectation is that service endpoints get uniformly loaded.

This solution works well for both cases, one where Clos fabric is Layer-3 only network and another where we have Evpn vxlan overlay network. Care must be taken though to select switch hardware that can support overlay Continue reading