DreamBig Semiconductor, Inc. — A4:5F:B9 (MA-L)

A4:5F:B9 is a 24-bit MA-L block registered to DreamBig Semiconductor, Inc., a US fabless chip company founded in 2019 and headquartered at 2860 Zanker Road, Suite 210, San Jose, CA. Unlike a consumer brand, DreamBig builds datacenter and AI networking silicon — its flagship Mercury is an 800G AI-SuperNIC with a hardware-offloaded RoCE v2 and UEC RDMA engine, built on the chiplet-based Mars platform (Ares networking, Deimos hub, Phobos extensibility chiplets). The practical consequence for OUI work: a MAC in A4:5F:B9 space almost certainly belongs to enterprise datacenter hardware — AI training/inference racks, GPU clusters, and high-performance compute nodes carrying SmartNICs or DPUs — not consumer, mobile, or IoT gear. An address from this block surfacing outside a datacenter context is therefore worth investigating. The company raised a $75M Series B in July 2024 (co-led by Samsung Catalyst Fund and the Sutardja family) and was acquired by Arm in a roughly $265M cash deal announced in late 2025, so the silicon may increasingly ship under the Arm umbrella even though the IEEE registration remains under DreamBig's name. No public CVEs or vulnerability disclosures for DreamBig products were found as of June 2026; the standard datacenter network-adapter risk posture applies — RDMA/RoCE-capable NICs in shared GPU fabrics are high-value targets if segmentation is weak.

IEEE assignment

A4:5F:B9 → DreamBig Semiconductor, Inc. [Confirmed] — IEEE the IEEE MA-L registry (line 736); vendor corroborated at https://www.dreambigsemi.com/

Registry / block size

MA-L (24-bit OUI), single prefix A4:5F:B9 [Confirmed] — IEEE the IEEE MA-L registry (MA-L block); no matching row in the IEEE MA-M registry (MA-M) or the IEEE MA-S registry (MA-S). NOTE: IEEE's public OUI data publishes NO assignment/registration date (the IEEE MA-L registry columns are only Registry, Assignment, Organization Name, Organization Address); any "date registered" on third-party tools is a database artifact, not an IEEE fact.

HQ / country

2860 Zanker Road, Suite 210, San Jose, CA 95134, US [Confirmed] — IEEE the IEEE MA-L registry address; matches https://www.dreambigsemi.com/our-company

Company status

active; acquired by Arm (~$265M cash, announced late 2025) [Confirmed] — https://www.sdxcentral.com/news/arm-to-acquire-ai-networking-chipmaker-dreambig-in-265m-deal/

Founded

2019, US fabless semiconductor company [Confirmed] — https://www.dreambigsemi.com/our-company

Device types

datacenter and AI networking silicon — AI SuperNICs (Mercury, 800G), SmartNICs, DPUs, and chiplet-based networking components for AI/HPC/cloud; enterprise/datacenter PCIe adapters and chiplets, not consumer or IoT end-user devices

[Confirmed] — https://www.dreambigsemi.com/our-products, https://www.dbdpu.com/

Notable products

Mercury (800G AI-SuperNIC with hardened RoCE v2 + UEC RDMA engine); Mars Chiplet Platform (Ares networking, Deimos chiplet hub, Phobos extensibility) [Confirmed] — https://www.prnewswire.com/news-releases/dreambig-announces-world-leading-800g-ai-supernic-chip-mercury-with-fully-hw-offloaded-roce-v2--uec-rdma-engine-302342748.html

Funding

$75M Series B, July 2024, co-led by Samsung Catalyst Fund and the Sutardja family [Confirmed] — https://www.prnewswire.com/news-releases/dreambig-closes-75m-series-b-funding-round-co-led-by-samsung-catalyst-fund-and-sutardja-family-to-enable-ai-inference-and-training-solutions-to-the-masses-302197507.html

Assignment / registration date

Unknown — IEEE publishes no OUI registration dates; the IEEE MA-L registry has no date column and no third-party scrape date is recorded here [Confirmed that none exists] — IEEE the IEEE MA-L registry

Security context

no DreamBig-specific CVEs or public vulnerability disclosures found as of June 2026; datacenter RDMA/RoCE NIC risk posture applies (high-value targets in shared GPU fabrics if poorly segmented) [Likely] — single-angle web check, no advisory found; https://www.dreambigsemi.com/our-products

Related vendors

Arm (acquirer, ~$265M deal announced late 2025; IEEE registration still under DreamBig) [Confirmed] — https://www.sdxcentral.com/news/arm-to-acquire-ai-networking-chipmaker-dreambig-in-265m-deal/

Analyst note

an A4:5F:B9 address identifies enterprise datacenter networking silicon (AI/HPC servers, GPU clusters), not consumer or IoT hardware; an appearance outside a datacenter context warrants investigation.