100G Ethernet MAC/PCS SOC — 5G Infrastructure ASIC
The Verification Challenge
The client was developing a 100G Ethernet MAC/PCS IP for integration into a 5G transport aggregation ASIC. The design implemented IEEE 802.3-2018 RS-FEC (Reed-Solomon Forward Error Correction) and supported both 100GBASE-R4 (4x25G) and 100GBASE-R10 (10x10G) configurations. The APB register map contained 847 registers. Key risks included RS-FEC encoder/decoder functional correctness, multi-lane alignment marker insertion/detection, and PCS lane deskew operation.
SSN Methodology & Solution
- RS-FEC Reference Model: Developed a bit-accurate SystemC reference model of the RS(528,514) encoder and decoder, integrated via DPI-C. Every FEC symbol correction was validated against the reference model.
- Multi-Lane Coverage: Built cross-coverage between lane configuration (4x25G vs 10x10G), AM insertion period, and deskew buffer depth — 156 cross bins in total.
- APB RAL Model: Generated a UVM RAL model from the client’s IP-XACT register specification. Automated register smoke test suite covered reset values, read-write access types, field masking, and aliased register detection.
- Error Injection: Systematic injection of single-symbol, burst, and uncorrectable FEC errors to verify the error indication interface and SNMP-compatible counter behavior.
- AXI4-Stream Verification: Full TKEEP/TLAST/TUSER protocol checking on the data plane, including minimum and maximum frame sizes, VLAN-tagged frames, and jumbo frame support.
Results
Metric | Result |
Functional Coverage | 100% — 1,247 functional bins closed including all RS-FEC error correction scenarios. |
Register Coverage | 100% of 847 registers covered: reset value, write, read, write-1-clear, and read-only fields. |
Bugs Found | 21 bugs found; 2 were critical RS-FEC decoder logic errors that would have caused data corruption under bursty error conditions. |
Tape-Out Result | First-time silicon. ORAN Alliance compliance testing passed on first attempt post-silicon. |
