vpp

VPP moves network packets through software at speeds people used to need custom hardware for. It runs a full router and switch on a standard x86 or ARM server: routing, switching, tunneling, ACLs, NAT, and more, processing packets in batches to stay fast. Apache 2.0, hosted by the FD.io project and originally built at Cisco.

This is infrastructure plumbing, not an app. You get the best performance on bare metal with the network card bound to DPDK and CPU cores pinned to packet work. Pre-built packages exist, but tuning VPP for real throughput means understanding hugepages, core affinity, and your NIC. It is built for people who create network functions, not people who consume them.

If you are building a software router, a load balancer, a 5G data plane, or a high-throughput gateway, VPP is one of the few open projects that performs at carrier scale. Solo developers and product teams almost never need this. Network engineering teams, telcos, and infrastructure vendors are the audience. For ordinary service-to-service networking, a service mesh or a cloud load balancer is the right tool.

The catch is the learning curve. VPP is powerful and well documented, but the core concepts (graph nodes, vectors, plugins) are unfamiliar even to experienced network engineers. Expect a real ramp before you ship anything on it.