p4lang/behavioral-model

How p4lang/behavioral-model works

bmv2 is a C++ reference software switch that interprets compiler-generated P4 JSON to process packets, and provides target variants and control-plane interfaces for development and debugging. The principal workflow is packet reception, parsing, ingress and egress P4 control flow, deparsing, and transmission. The graph also shows configuration loading, target runtimes, and debugging/observation capabilities. Workflow details are evidenced by the sampled simple-router implementation; other target and service wiring is included only where documented or shown in sampled entry points.

Main entry points: simple_switch.cpp Simple switch · server.cpp Thrift runtime · pipeline.cpp P4 pipeline · queue.h Packet queues

Components 20

Packet processing

Switch core src/bm_sim/switch.cpp
Packet and PHV src/bm_sim/packet.cpp
P4 parser src/bm_sim/parser.cpp
P4 pipeline src/bm_sim/pipeline.cpp
P4 deparser src/bm_sim/deparser.cpp
Packet queues include/bm/bm_sim/queue.h

P4 model

P4 object loader src/bm_sim/P4Objects.cpp
Match-action tables src/bm_sim/match_tables.cpp
Stateful resources src/bm_sim/stateful.cpp
Multicast replication src/bm_sim/simple_pre.cpp

Switch targets

Simple switch targets/simple_switch/simple_switch.cpp
gRPC switch targets/simple_switch_grpc/main.cpp
PSA switch targets/psa_switch/main.cpp
PNA NIC targets/pna_nic/main.cpp

Control plane

Thrift runtime src/bm_runtime/server.cpp
PI runtime PI/src/pi.cpp

Debugging

Remote debugger src/bm_sim/debugger.cpp
Event logger src/bm_sim/event_logger.cpp

Other components

Packet ports
P4 JSON

Connections 22

Packet ports → Simple switch: delivers packets
Simple switch → Packet queues: enqueues packets
Packet queues → Packet and PHV: supplies packets
Simple switch → P4 parser: parses packets
P4 parser → Packet and PHV: populates headers
Simple switch → P4 pipeline: applies control flow
P4 pipeline → Match-action tables: looks up entries
Match-action tables → Stateful resources: uses resources
Simple switch → P4 deparser: deparses packets
P4 deparser → Packet queues: queues output
Simple switch → Packet ports: transmits packets
P4 JSON → P4 object loader: configures model
P4 object loader → Switch core: loads P4 objects
Simple switch → Thrift runtime: starts service
gRPC switch → Thrift runtime: starts service
PSA switch → Thrift runtime: starts service
PNA NIC → Thrift runtime: starts service
Thrift runtime → Switch core: controls switch
PI runtime → Switch core: implements control API
Simple switch → Multicast replication: supports multicast
P4 pipeline → Remote debugger: notifies control flow
P4 pipeline → Event logger: records events

More C++ diagrams: ros2/demos · hasherezade/bearparser · horionclient/horion · adepierre/sniffcraft · frepple/frepple

Drawn by GitDiagram on September 29, 2026 from the repository's file tree, README and source files. Read as Markdown ·