Broadcom has accelerated its PCIe/CXL roadmap, introducing the Atlas 3 and Atlas 4 platforms to enhance the open AI ecosystem with increased lane counts and bandwidth. The Atlas 3 platform features PCIe Gen 6 and CXL 3.1 support, enabling interoperability among ecosystem partners and allowing for complex AI architecture fabric configurations. Future advancements include Atlas 4 with PCIe Gen 7 capabilities, expected to provide significant performance enhancements by December 2025.

1. Broadcom Accelerates PCIe/CXL
Roadmap to Enable the Open
AI Ecosystem

2. Broadcom Accelerates PCIe/CXL Roadmap
to Enable the Open AI Ecosystem
Rick Kutcipal, Product Planner, Broadcom
Sreeni Bagalkote, Product Planner, Broadcom
AI

3. Broadcom PCIe & CXL Switches
Predictable high-quality execution for 10+ Years
Increasing lane counts for AI systems
Simple fanout  Internal fabric
86x bandwidth increase
Low power / lane

4. Atlas 3: PCIe Gen 6 & CXL 3.1 Switch
144 lane switch in 5nm
technology
Peer-to-Peer across virtual
hierarchies
CXL.mem, CXL.cache, & CXL
fabric support
Best in class SerDes (> 36db
margin)
Embedded PCIe analyzer
Dec 2024 Samples

5. PCIe Gen 5  Gen 6 Complexity
Features Gen 1 Gen 2 Gen 3 Gen 4 Gen 5 Gen 6 Complexity
Physical
Bus Freq. (GHz) 2.5 5 8 16 32 32
High Complexity
Throughput (MB/s) 4 8 16 32 64 128
Physical Encoding NRZ NRZ + PAM4
Link
Link Data Integrity ECRC ECRC + FEC
High Complexity
Wire Protocol Variable length packets Variable + Fixed length (Flit)
Replay Protocol Packet ACK/NAK Packet ACK/NAK + Flit-based ACK
Transaction
Packet Formats 4 Header Types, 22 Packet types 7 Header Types, 61 Packet types
High Complexity
Credit Protocol 3 credit types
3 credit + Flit credits, 2 shared
credits
Encryption Support - Link and Stream(end-to-end)
PCIe Gen 5  Gen 6 transition is highly complex

6. • PCI Gen 6 / CXL 3.1
• Opening to all ecosystem
partners for interop
• Available Now
• Contact for details
rick.kutcipal@broadcom.com
sreenivas.bagalkote@broadcom.c
om
Atlas 3 FPGA Platform Available for Interop
1
2
3 4
5
6
7
8
9
1 Atlas 3 FPGA platform
2 PCIe subsystem
3 CXL subsystem
4 ARM 15
5 Sprite daughter card
6 Debug daughter card
7 Drive connection daughter card
8 Host connection daughter card
9 Atlas 3 FPGA setup

7. Atlas 3 Rapid Development Kit (RDK)
• Multi-host PCIe & CXL topologies
• Create fabric using multiple RDKs
• CXL memory modules via riser card
• Allows out-of-band BMC connection
• Validated with Broadcom Gen 6 retimer
Available Dec 2024

8. Atlas Enables Open AI Architectures
CPU
CPU CPU
CPU
GPU
GPU GPU
GPU GPU
GPU GPU
GPU
CXL Memory
Ethernet NIC
Storage
CXL Memory
Ethernet NIC
Storage
Open internal AI fabric
Open scale-up fabric

9. Announcing Atlas 4 – PCIe Gen 7 & CXL
Switch
128 Gb/s
Broadcom PAM4 SerDes
3nm Process Technology
Sample Availability Dec 2025
Atlas4
AI

10. Thank you!