  To interconnect their growing number of servers, current supercomputers and
data centers are starting to adopt low-diameter networks, such as HyperX,
Dragonfly and Dragonfly+. These emergent topologies require balancing the load
over their links and finding suitable non-minimal routing mechanisms for them
becomes particularly challenging. The Valiant load balancing scheme is a very
popular choice for non-minimal routing. Evolved adaptive routing mechanisms
implemented in real systems are based on this Valiant scheme.
  All these low-diameter networks are deadlock-prone when non-minimal routing
is employed. Routing deadlocks occur when packets cannot progress due to cyclic
dependencies. Therefore, developing efficient deadlock-free packet routing
mechanisms is critical for the progress of these emergent networks. The routing
function includes the routing algorithm for path selection and the buffers
management policy that dictates how packets allocate the buffers of the
switches on their paths. For the same routing algorithm, a different buffer
management mechanism can lead to a very different performance. Moreover,
certain mechanisms considered efficient for avoiding deadlocks, may still
suffer from hard to pinpoint instabilities that make erratic the network
response. This paper focuses on exploring the impact of these buffers
management policies on the performance of current interconnection networks,
showing a 90\% of performance drop if an incorrect buffers management policy is
used. Moreover, this study not only characterizes some of these undesirable
scenarios but also proposes practicable solutions.
