Switch

Scope: Legacy Days. For the Days AGO switch-egress LP model, see Switches and logical processes.

Legacy has one demultiplexer actor per physical topology switch. PacketSwitch does not queue packets or serialize links. Its outputs map connects the demultiplexer to schedulers, endpoint actors, or host-attachment models.

Each switch stores two flow tables:

• fib: flow_id -> next_id routes data toward the sink.
• r_fib: flow_id -> previous_id routes TCP ACKs and control packets toward the source.

packet_received classifies packets with neither ack nor control as forward data. It sends ACK and control packets through r_fib. Topology::route_flows installs both tables after it computes all paths.

The Nexosim event clock drives the handler. PacketSwitch::time is a seconds view of Context::time(). Test assertions permit packet.time to precede the current event, so the packet field is a compatibility timestamp rather than a second clock.