Predictably sharing the network is critical to achieving
high utilization in the datacenter. Past work has focussed
on providing bandwidth to endpoints, but often
we want to allocate resources among multi-node services.
In this paper, we present Parley, which provides
service-centric minimum bandwidth guarantees, which
can be composed hierarchically. Parley also supports
service-centric weighted sharing of bandwidth in excess
of these guarantees. Further, we show how to configure
these policies so services can get low latencies even at
high network load. We evaluate Parley on a multi-tiered
oversubscribed network connecting 90 machines, each
with a 10Gb/s network interface, and demonstrate that
Parley is able to meet its goals.