USB

USB4 v1 (tunnelling / path layer)

An independent clean-room USB4 tunnelling / path-layer VIP: a router with adapters and a per-hop path table…

shippingGroup USBStandard USB-IF USB4 Specification — transport and tunnelling layer

Available now — real, tested verification collateral, not a roadmap placeholder.

Verification IP is not safety-rated. These are testbench components — no ASIL target, no FMEDA, no IP-XACT, no safety-mechanism interface. They exist to help you verify a design, not to carry a safety argument. The safety soft-IP catalog is over here.

The deliverable

What you get

Bus-functional model

An independent driver for the protocol, written clean-room from the public specification — not derived from our own RTL, so it is a genuine second source.

Passive protocol checker

A monitor that watches the bus and asserts the spec’s rules continuously, so a violation fails the run where it happens rather than downstream.

Self-checking interop testbench

A one-command testbench that drives the model against real RTL and hard-checks the result — reproduce every claim on day one.

An independent clean-room USB4 tunnelling / path-layer VIP: a router with adapters and a per-hop path table, a separately written connection manager that builds paths by writing one hop at a time, and a passive link checker (“usb4/, make usb4_oss, 20/20 checks). Covers HopID-based forwarding, the control path, adapter enable, per-link credit flow control, route-string depth, and protocol tunnels (USB3, DisplayPort, PCIe) sharing one link. Six rules, each pinned by a per-rule mask to its own injected fault. SCOPE: the transport layer. The USB4 physical layer and lane bonding, Gen2/3/4 line coding, the full router configuration space, sideband discovery, and the tunnelled protocols’ own semantics (vip-usb32, vip-dp20/21, vip-pcie) are NOT modelled — a tunnel payload here is an opaque token, which is what a tunnel is meant to treat it as. The sharpest result is a NEGATIVE one, and it is the strongest instance of this shape in the catalog. A HopID is a LOCAL LABEL, not a global identifier: which tunnel a packet belongs to exists only as table entries distributed across the routers on its path. T9 crosses two of those entries with a single wrong write. Every packet on the link stays perfectly legal — HopID non-zero and in range, adapter valid, route legal, credit respected — and the DisplayPort payload is delivered to the USB3 endpoint. The checker is blind by construction, and no rule about a packet could fix it: the packet is not wrong, the distributed table is, and the table is not on the wire.

Key Features

Routers with adapters and a per-hop path table (ingress adapter + HopID → egress)
Control path (HopID 0), path set/clear and adapter-enable control packets
Protocol tunnels (USB3 / DisplayPort / PCIe) sharing one link, terminating by path config
Per-link credit flow control and route-string depth limiting
Passive checker, 6 rules, each pinned by a per-rule mask to its own injected fault
The crossed-path blind spot named and asserted, not papered over

Standards & Compliance

USB-IF USB4 Specification — transport and tunnelling layer

Interested in the USB4 v1 (tunnelling / path layer) VIP?

Deliverables, the file manifest, and licensing terms are shared under a mutual NDA.

Talk to us →See related VIP

Verification IP is testbench collateral and is deliberately not safety-rated: no ASIL target, no FMEDA, and no IP-XACT descriptor. It carries no functional-safety claim.

circuit-design.space · +1-971-357-1400 · anovickis@circuit-design.space