USRP X310 Network Setup: Fix Connection Issues & Boost Performance

The USRP X310 is a high-performance Software Defined Radio (SDR) that communicates with host computers through Gigabit and 10 Gigabit Ethernet interfaces. Proper network configuration is crucial for achieving optimal streaming performance and avoiding common connectivity issues. This comprehensive guide covers everything from basic IP setup to advanced performance optimization techniques.

Default IP Address Configuration

Understanding USRP X310 Network Architecture

The USRP X310 stores multiple IP addresses in its EEPROM, with each combination of Ethernet port and interface type having its own dedicated address:

Initial Setup and Device Discovery

Basic Network Configuration Steps

Step 1: Configure Host Network Interface

For Gigabit Ethernet connection (most common):

sudo ifconfig eth1 192.168.10.1 netmask 255.255.255.0

For 10 Gigabit Ethernet on Port 1:

sudo ifconfig eth1 192.168.40.1 netmask 255.255.255.0

Step 2: Test Basic Connectivity

Ping the USRP device:

ping 192.168.10.2  # For Gigabit Ethernet
ping 192.168.40.2  # For 10GbE Port 1

Step 3: Discover USRP Devices

Use UHD utilities to verify detection:

uhd_find_devices
uhd_usrp_probe --args addr=192.168.10.2

Common Discovery Issues and Solutions

Problem: uhd_find_devices returns "No UHD Devices Found" but ping works

Solutions:

1. Firewall Configuration: Add iptables rule to allow UHD broadcast traffic:

   sudo iptables -A INPUT -p udp --sport 49152 -j ACCEPT

2. Specify Device Address Explicitly:

   uhd_find_devices --args addr=192.168.10.2

3. Disable Network Manager: Prevent automatic IP configuration changes:

   sudo systemctl stop NetworkManager
   sudo systemctl disable NetworkManager

FPGA Image Management

Understanding HG vs XG Image Types

The USRP X310 supports two main FPGA image types that determine interface capabilities:

• HG Image (Host+Gen3): One 1 Gigabit Ethernet + One 10 Gigabit Ethernet interface
• XG Image (Gen3x2): Two 10 Gigabit Ethernet interfaces for maximum throughput

The XG image is required for dual 10GbE operation and 200 MS/s streaming performance.

Downloading FPGA Images

Step 1: Download Compatible Images

Use the UHD images downloader to get FPGA images matching your UHD version:

# Download all compatible images for your UHD version
uhd_images_downloader

# List available image URLs (optional)
uhd_images_downloader -l

# Download to custom location (optional)
uhd_images_downloader --download-location=/custom/path

Default Image Locations:

• Linux: /usr/share/uhd/images/
• Windows: C:\Program Files\UHD\share\uhd\images\
• Custom location: Set UHD_IMAGES_DIR environment variable

Step 2: Load FPGA Image to Device

For XG image (dual 10GbE support):

uhd_image_loader --args="type=x300,addr=192.168.10.2" --fpga-path="/usr/share/uhd/images/usrp_x310_fpga_XG.bit"

For HG image (1GbE + 10GbE support):

uhd_image_loader --args="type=x300,addr=192.168.10.2" --fpga-path="/usr/share/uhd/images/usrp_x310_fpga_HG.bit"

Auto-detect image (recommended):

uhd_image_loader --args="type=x300,addr=192.168.10.2"

Power Cycle Required: After loading FPGA image, power cycle the USRP X310 for changes to take effect.

Verifying FPGA Compatibility

Check FPGA compatibility numbers after image loading:

uhd_usrp_probe --args addr=192.168.10.2 | grep -i fpga

Common Compatibility Error:

"Expected FPGA compatibility number 38, but got 36"

Solution: Download and flash correct FPGA image using commands above.

SFP+ Transceiver Configuration

Selecting Compatible SFP+ Modules

The USRP X310 supports multiple SFP+ transceiver types:

• SFP+ to RJ45 Adapters: For Gigabit Ethernet over standard cables
• SFP+ DAC Cables: Direct Attach Copper for 10GbE connections
• SFP+ Optical Transceivers: For long-distance 10GbE connections

Recommended SFP+ Adapters for Reliability:

• Intel Ethernet SFP+ adapters
• Cisco compatible modules
• Mellanox ConnectX series

Hardware Connection Verification

Green LINK LED Indicators:

• Port 0: Should illuminate with compatible SFP+ adapter
• Port 1: Lights up for 10GbE connections

If LEDs don't illuminate:

1. Try a different known-working SFP+ module
2. Verify power connection to USRP X310
3. Check FPGA image compatibility (HG vs XG)

10 Gigabit Ethernet Optimization

Dual 10GbE Configuration

For maximum 200 MS/s streaming performance, configure dual 10 Gigabit Ethernet:

Step 1: Download and Install XG FPGA Image

# Download compatible images first
uhd_images_downloader

# Load XG image for dual 10GbE support
uhd_image_loader --args="type=x300,addr=192.168.10.2"

# Power cycle device after image loading

Step 2: Configure Dual Network Interfaces

sudo ifconfig eth0 192.168.30.1 netmask 255.255.255.0 mtu 9000
sudo ifconfig eth1 192.168.40.1 netmask 255.255.255.0 mtu 9000

Step 3: Test Dual Interface Performance

benchmark_rate --args="type=x300,addr=192.168.30.2,second_addr=192.168.40.2" --rx_rate 200e6

MTU Size Optimization

Maximum Transmission Unit (MTU) configuration significantly impacts performance:

Recommended MTU Settings:

• Gigabit Ethernet: 1500 bytes (default)
• 10 Gigabit Ethernet: 9000 bytes (jumbo frames)

sudo ifconfig eth1 mtu 9000
# Verify MTU setting
ifconfig eth1 | grep MTU

MTU Performance Impact:

• Default 8000 bytes: Standard performance
• 1000-2000 bytes: Improved latency, potential throughput reduction
• 9000 bytes: Maximum throughput for 10GbE

Socket Buffer Optimization

Network Buffer Configuration

Increase socket buffer sizes to prevent packet drops:

Temporary Configuration:

sudo sysctl -w net.core.rmem_max=33554432
sudo sysctl -w net.core.wmem_max=33554432

Permanent Configuration in /etc/sysctl.conf:

net.core.rmem_max=33554432
net.core.wmem_max=33554432
net.core.rmem_default=262144
net.core.wmem_default=262144

Apply changes:

sudo sysctl -p

Ethernet NIC Descriptor Tuning

For 10 Gigabit Ethernet cards, increase RX descriptors:

# Check current settings
ethtool -g eth1

# Increase RX descriptors
sudo ethtool -G eth1 rx 4096

# Set interrupt coalescing
sudo ethtool -C eth1 rx-usecs 25

Advanced Performance Optimization

DPDK Support

Data Plane Development Kit (DPDK) provides highest streaming performance:

Installation:

# Install DPDK dependencies
sudo apt-get install dpdk dpdk-dev

# Bind network interface to DPDK
sudo dpdk-devbind.py --bind=uio_pci_generic eth1

Usage with USRP X310:

# Set DPDK transport
export UHD_DPDK_CTX="eth1"
benchmark_rate --args="type=x300,addr=192.168.30.2,use_dpdk=1"

Multi-Device Configuration

For multiple USRP X310 devices, ensure unique subnets:

Device 1:

• Host IP: 192.168.10.1
• USRP IP: 192.168.10.2

Device 2:

• Host IP: 192.168.110.1
• USRP IP: 192.168.110.2

Configure USRP IP addresses:

usrp_burn_mb_eeprom --args="addr=192.168.10.2" --values="ip-addr0=192.168.110.2"
# Power cycle device after EEPROM change

Troubleshooting Common Issues

Connection Problems Checklist

Device Not Detected:

1. Verify power connection and front panel LEDs
2. Check SFP+ transceiver compatibility
3. Confirm host IP configuration matches USRP subnet
4. Test with explicit device addressing
5. Disable firewall/iptables temporarily

FPGA Image Issues:

1. Run uhd_images_downloader to get compatible images
2. Use uhd_image_loader with correct device address
3. Verify compatibility numbers match UHD version
4. Power cycle device after image loading
5. Check available images in /usr/share/uhd/images/

Performance Issues:

1. MTU size: Set to 9000 for 10GbE
2. Socket buffers: Increase to 32MB
3. NIC descriptors: Increase RX ring buffer
4. CPU affinity: Bind processes to specific cores
5. Real-time scheduling: Use high-priority process scheduling

UHD Utility Commands for Diagnostics

Device Discovery:

# Basic discovery
uhd_find_devices

# Specific device type
uhd_find_devices --args="type=x300"

# By IP address
uhd_find_devices --args="addr=192.168.10.2"

Device Information:

# Complete device probe
uhd_usrp_probe --args addr=192.168.10.2

# Property tree inspection
uhd_usrp_probe --args addr=192.168.10.2 --tree

Performance Testing:

# RX benchmark
benchmark_rate --args addr=192.168.10.2 --rx_rate 50e6 --duration 30

# TX benchmark  
benchmark_rate --args addr=192.168.10.2 --tx_rate 50e6 --duration 30

# Full duplex test
benchmark_rate --args addr=192.168.10.2 --rx_rate 25e6 --tx_rate 25e6

Network Interface Recovery

If network configuration becomes corrupted:

Method 1: Reset to Defaults

# Reset EEPROM to factory defaults
usrp_burn_mb_eeprom --args="type=x300,recover_mb_eeprom" --values="ip-addr0=192.168.10.2"

Method 2: JTAG Recovery

For completely unresponsive devices, use JTAG interface:

# Flash FPGA via JTAG
uhd_image_loader --args="type=x300,addr=192.168.10.2,fpga=HG" --jtag

Performance Benchmarking

Expected Throughput Rates

Interface Performance Limits:

• Gigabit Ethernet: ~50 MS/s (16-bit I/Q)
• Single 10GbE: ~100 MS/s per port
• Dual 10GbE: ~200 MS/s total (100 MS/s per port)
• PCIe: ~200 MS/s (maximum device capability)

Monitoring Performance Indicators

Watch for Error Indicators:

• 'O' characters: Overflow (samples from USRP not processed fast enough)
• 'U' characters: Underflow (host not providing samples fast enough)
• 'D' characters: Dropped packets (network configuration issue)

Performance Optimization Checklist:

1. ✓ Compatible FPGA image loaded (HG or XG)
2. ✓ uhd_images_downloader run for latest images
3. ✓ MTU set to 9000 for 10GbE
4. ✓ Socket buffers increased to 32MB
5. ✓ NIC descriptors maximized
6. ✓ CPU frequency scaling disabled
7. ✓ Real-time kernel (optional but recommended)
8. ✓ DPDK transport enabled for maximum performance

Conclusion

Proper USRP X310 network configuration requires attention to FPGA image compatibility, IP addressing, MTU settings, socket buffers, and hardware compatibility. Following this comprehensive guide ensures reliable connectivity and optimal streaming performance for your SDR applications.

Key Takeaways:

• Always run uhd_images_downloader first to get compatible FPGA images
• Use XG image for dual 10GbE and maximum throughput
• Verify SFP+ transceiver compatibility
• Use jumbo frames (MTU 9000) for 10GbE connections
• Increase socket buffer sizes to prevent drops
• Configure firewall rules for UHD discovery
• Monitor performance with benchmark_rate utility
• Consider DPDK for maximum throughput applications

For production deployments, implement these optimizations systematically and validate performance using the provided benchmarking commands. Always ensure FPGA image compatibility matches your UHD version before troubleshooting network issues.