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diff --git a/docs/gettingstarted/developers/softwarearchitecture.md b/docs/gettingstarted/developers/softwarearchitecture.md new file mode 100644 index 00000000000..a663134cd46 --- /dev/null +++ b/docs/gettingstarted/developers/softwarearchitecture.md @@ -0,0 +1,44 @@ +Software Architecture +===================== + +The fd.io vpp implementation is a third-generation vector packet +processing implementation specifically related to US Patent 7,961,636, +as well as earlier work. Note that the Apache-2 license specifically +grants non-exclusive patent licenses; we mention this patent as a point +of historical interest. + +For performance, the vpp dataplane consists of a directed graph of +forwarding nodes which process multiple packets per invocation. This +schema enables a variety of micro-processor optimizations: pipelining +and prefetching to cover dependent read latency, inherent I-cache phase +behavior, vector instructions. Aside from hardware input and hardware +output nodes, the entire forwarding graph is portable code. + +Depending on the scenario at hand, we often spin up multiple worker +threads which process ingress-hashes packets from multiple queues using +identical forwarding graph replicas. + +VPP Layers - Implementation Taxonomy +------------------------------------ + + + +- VPP Infra - the VPP infrastructure layer, which contains the core + library source code. This layer performs memory functions, works + with vectors and rings, performs key lookups in hash tables, and + works with timers for dispatching graph nodes. +- VLIB - the vector processing library. The vlib layer also handles + various application management functions: buffer, memory and graph + node management, maintaining and exporting counters, thread + management, packet tracing. Vlib implements the debug CLI (command + line interface). +- VNET - works with VPP\'s networking interface (layers 2, 3, and 4) + performs session and traffic management, and works with devices and + the data control plane. +- Plugins - Contains an increasingly rich set of data-plane plugins, + as noted in the above diagram. +- VPP - the container application linked against all of the above. + +It's important to understand each of these layers in a certain amount of +detail. Much of the implementation is best dealt with at the API level +and otherwise left alone. |