It is possible to use P4Broker to redirect read-only commands to a Perforce replica server (instead of processing those commands on the master Perforce server).
The idea is to reduce the main server load by processing many read-only commands on the replica server. The P4Broker enables Perforce administrators to configure a single server and host address for their users and transparently force commands to use the appropriate Perforce server (master or replica).
Redirecting commands to a replica server is most useful in older versions of the Perforce Server (2010.2 or 2011.1) when read-only replica servers were first introduced. The advent of Forwarding and Build Farm replicas (in 2012.1) and Edge Servers (2013.2) arguably reduces the need for P4Broker redirection to read-only replicas for reducing master server load.