  Deterministic communication means reliable packet forwarding with close to
zero packet loss and bounded latency. Packet loss or delay above a threshold
caused by, e.g., equipment failure or malfunction could be catastrophic for
applications that require deterministic communication. To meet loss related
targets, per-packet service protection has been introduced by deterministic
communications standards; it is provided by Frame Replication and Elimination
for Reliability (FRER) for Layer 2 Ethernet networks and by Packet Replication,
Elimination, and Ordering Functions (PREOF) for Layer 3 IP/MPLS networks.
  We have implemented FRER with two conceptually different methods: (1) in
eBPF/XDP as a lightweight software implementation; and (2) in userspace. We
evaluate our XDP FRER via an experimental analysis and compare the two FRER
implementations.
