Among the factors considered in the optimization are {HEAD ~ the characteristics} of the originating source and {TAIL ~ the network path} 
Among the factors considered in the optimization are { HEAD ~ the characteristics } of the originating source and { TAIL ~ the network path }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL