1. A computer-implemented method for selecting a peer egress appliance for data traffic to a software service through a network comprising a plurality of inter-connected ingress and egress network appliances, the method comprising: measuring one or more performance metrics of data traffic from at least two of the plurality of network appliances to an IP address associated with a software service, the IP address for the software service having been retrieved from a service directory; determining a derived performance metric for each network appliance to each IP address associated with the software service, the derived performance metric based at least in part on the measured one or more performance metrics; selectively advertising the derived performance metric by each network appliance among two or more of the plurality of network appliances; updating an advertised metric table at each of the plurality of network appliances with the derived performance metric received; and selecting a peer egress appliance for data traffic to the IP address associated with the software service, the selection based at least in part on the advertised derived performance metrics.