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