Building Google Cloud Platform Solutions

Backend services

Whereas network load balancers distribute traffic across target pools, global load balancers operate on backend services which are composed of one or more backends. Each backend is composed of a single managed or unmanaged instance group, a balancing mode, and a capacity scalar. Unlike NLBs, GLBs cannot balance traffic across arbitrary compute instances. Instead, instances can only be associated with GLBs through the use of an instance group.

Because backends operate on instance groups, they are regional resources. Backend services, on the other hand, may be regional or global resources, with a single backend service serving traffic to multiple backends. Both the balancing mode and capacity setting are used to tell the backend ...