[multicast] Bitmap-based multicast replication for sidecar-lite#152
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This adds multicast replication to sidecar-lite, emulating DPD's sidecar.p4 We manage 2 bitmaps per multicast destination (external, underlay), in which replication is driven via the `Replicate` extern (from p4rs #240). The ingress control block suppresses (or doesn't) these bitmaps based on the geneve multicast option tag, and then merges both into a single replication bitmap. This tag is read-only, matching DPD's sidecar.p4. OPTE (would) stamp it before the packet reaches the switch. Egress decap is gated on the reserved underlay subnet (ff04::/64, per RFC 7346 admin-local scope + Omicron) and tag=2 (Both), matching DPD's egress mcast_tag_check. Ports in the decap table get geneve stripped, others keep encapsulation for OPTE to handle on the receiving sled. Multicast dst MAC derivation (RFC 1112 for IPv4, RFC 2464 for IPv6) and per-port source MAC rewrite run on every replicated copy. Egress validates the outer IP multicast range before any mcast processing. ### References This work depends on the P4(rs) work in [#240](oxidecomputer/p4#240).
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This wires up the softnpu ASIC backend to support multicast end-to-end by translating DPD's sidecar.p4 table operations into sidecar-lite.p4's simplified P4 pipeline. ## AsicMulticastOps We replace the stubbed AsicMulticastOps implementation (which returned "OperationUnsupported" for group creation and port addition with in-memory group tracking via McGroupData, following the tofino_stub pattern. Group membership is used by the table translation layer to build port bitmaps for sidecar-lite's Replicate extern. Ports >= 128 are rejected at add time to match sidecar-lite's 128-bit bitmap width. ## Table translation (asic/src/softnpu/table.rs) We map sidecar.p4 table names to sidecar-lite equivalents and translate action parameters where the designs differ for emulation. All multicast action arms are gated with #[cfg(feature = "multicast")]. ## References - [softnpu #183](oxidecomputer/softnpu#183) - [propolis #1093](oxidecomputer/propolis#1093) - [p4rs #240](oxidecomputer/p4#240) - [sidecar-lite #152](oxidecomputer/sidecar-lite#152) - tokio: 1.50 (due to softnpu) - oxide-tokio-rt: 0.1.3 (following-up from tokio's move to 1.50)
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This wires up the softnpu ASIC backend to support multicast end-to-end by translating DPD's sidecar.p4 table operations into sidecar-lite.p4's simplified P4 pipeline. ## AsicMulticastOps We replace the stubbed AsicMulticastOps implementation (which returned "OperationUnsupported" for group creation and port addition with in-memory group tracking via McGroupData, following the tofino_stub pattern. Group membership is used by the table translation layer to build port bitmaps for sidecar-lite's Replicate extern. Ports >= 128 are rejected at add time to match sidecar-lite's 128-bit bitmap width. ## Table translation (asic/src/softnpu/table.rs) We map sidecar.p4 table names to sidecar-lite equivalents and translate action parameters where the designs differ for emulation. All multicast action arms are gated with #[cfg(feature = "multicast")]. ## References - [softnpu #183](oxidecomputer/softnpu#183) - [propolis #1093](oxidecomputer/propolis#1093) - [p4rs #240](oxidecomputer/p4#240) - [sidecar-lite #152](oxidecomputer/sidecar-lite#152) - tokio: 1.50 (due to softnpu) - oxide-tokio-rt: 0.1.3 (following-up from tokio's move to 1.50)
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This adds multicast replication to sidecar-lite, emulating DPD's sidecar.p4
We manage 2 bitmaps per multicast destination (external, underlay), in which replication is driven via the
Replicateextern (from p4rs #240). The ingress control block suppresses (or doesn't) these bitmaps based on the geneve multicast option tag, and then merges both into a single replication bitmap. This tag is read-only, matching DPD's sidecar.p4. OPTE (would) stamp it before the packet reaches the switch.Egress decap is gated on the reserved underlay subnet (ff04::/64, per RFC 7346 admin-local scope + Omicron) and tag=2 (Both), matching DPD's egress mcast_tag_check. Ports in the decap table get geneve stripped, others keep encapsulation for OPTE to handle on the receiving sled.
Multicast dst MAC derivation (RFC 1112 for IPv4, RFC 2464 for IPv6) and per-port source MAC rewrite run on every replicated copy. Egress validates the outer IP multicast range before any mcast processing.
References
This work depends on the P4(rs) work in #240.