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UDP Offload Engine

UOE IP Core for 10/25/50/100GbE

Atomic Rules UDP Offload Engine (UOE) is a UDP FPGA IP Core that allows for immediate operation at 10, 25, 40, 50, or 100GbE. The UOE IP core implements the UDP standard RFC 768, including checksum, segmentation and reassembly hardware offload. 

This offloads much of the work described in RFC 768 from software to hardware. In doing so, line rates of 25, 50, and 100GbE are achievable.

The UOE IP core enables application-level UDP datagrams to be concurrently sent and received on a LAN or across a network. An integral IGMPv2 multicast pre-selector removes unwanted traffic, and L4 UDP multicasts are pre-selected so that user applications don’t have to perform this function. The UOE IP core is tested for operation with popular FPGA vendors’ Ethernet MACs.

Full line rate with no packet loss

Operate at any line rate up to 100GbE

Offloads UDP standard RFC 768


  • Future proof your application; optimize throughput for all line rates
  • Operates at 10/25/50/100GbE
  • Run full line rate with no packet loss, even for very small packets
  • Offloads UDP standard RFC 768 from software to hardware
  • Robust multicast support

Offload UDP at
full line rate
up to 100GbE

Block Diagram, Data Sheet and Product Details

Product Operation

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RTL sequential circuits in the UOE IP core handle the real-time interconversion of user datagrams and Ethernet frames. The core can function simultaneously as a UDP Sender and a UDP Receiver.

To send a datagram, the core is presented with a datagram and metadata describing the destination and port. If the MAC address for the destination IP address is unknown, the ARP circuit in the core resolves it. If the PDU of the datagram being sent exceeds the MTU, the core segments the datagram into fragments.

To receive, the core listens for Ethernet frames that encapsulate a UDP/IP payload. If the checksums are correct, it forms the datagram out of one or more fragments. When an entire datagram is ready, it is presented to the application logic along with its metadata.
When receiving multicast datagrams, the core preselects and delivers to the application only the host groups that have been joined by IGMP. This capability offloads the task of decoding the 228 ClassD multicast addresses to a 4-bit code encoding 16 host groups.

Detailed Feature List


  • UDP/IPv4 (RFC 768, RFC 791)
  • Hardware checksum, segmentation, and reassembly offload
  • Multicast (IGMPv2) capability
    • Join and leave support for receiving 16 Class-D groups
    • Send and receive multicast host groups
    • Receive pre-selecting offload (discard of unsubscribed multicasts)
  • Concurrent datagram send and receive
  • Ethernet packet: programmable frame MTU up to 16K Bytes (Super-Jumbo Frame support)
  • UDP packet arbitrary datagram PDU up to
  • IPv4 limit of 64K Bytes
  • 16 Entry ARP cache (RFC 826)
  • ICMP (unsegmented echo response message type only, used by “ping”)
  • VLAN (IEEE 802.1Q) support
  • Layer 3 direct, allowing non-UDP application connectivity
  • Statistics accessible by control-plane interface
  • Low-Area implementation, allowing multiple core instances per FPGA
  • Industry-standard AXI4 Interfaces (Avalon-Adapted on Altera devices)

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Reference Examples

Atomic Rules offers UDP IP reference designs for a range of BittWare cards. Atomic Rules UOE IP Core can operate at up to 400 MHz in such cases where 25 GbE must be implemented with the smallest footprint possible. 


The IP core is available in Named-Project or Site-License forms. Both versions include the elements needed for implementation, including a self-validating test bench. Most of the verification IP is also synthesizable, enabling testing to be performed at line rate, not just within a Verilog simulator. 

Named-Project: Allows the product to be used on one named project from development through production using one or more bitstreams including compiled versions of the product on authorized FPGA device(s). The project SLA prohibits use on derivative projects.

Site-License: Allows the product to be used at one authorized location from development through production using one or more bitstreams including compiled versions of the product on authorized FPGA device(s). The site SLA allows the product’s use on derivative projects from the authorized location.

Sample Implementation Results

64BAMD 78K 74K59400MHz 
64BAltera (Stratix & Agilex)73K123K230 M20K500MHz (Agilex)
8BAMD 22K21K44400MHz
8BAltera (Stratix & Agilex)23K32K88 M20K500MHz (Agilex)

Compatible FPGA Cards

The UDP Offload IP is compatible with all current BittWare cards with AMD UltraScale+, Intel Stratix 10 and Intel Agilex FPGAs.

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About the Company

Provider of FPGA IP components and solutions for networking and quality-of-time. IP offerings include Arkville data mover for high-throughput, low-latency communications between host memory and FPGA fabric logic.

Interested in Pricing or More Information?

Our technical sales team is ready to provide availability and configuration information, or answer your technical questions.