srsRAN CU/DU fails to establish fronthaul connection with LiteOn FlexFi-RU on Kubernetes

[motangpuar]

Problem

The srsRAN CU/DU cannot establish fronthaul (FH) connection with LiteOn O-RU despite following the official srsRAN guide. The gNodeB receives no RX traffic from the O-RU, though the SR-IOV interface attaches successfully to the container.

Cluster Configuration:

• CPU: Intel(R) Xeon(R) Gold 6326 CPU @ 2.90GHz
• RAM: 128 GB
• OS: RHEL 9.5
• Kernel: 5.14.0-570.49.1.el9_6.x86_64+rt
• Kubernetes: Vanilla v1.31.13
• Container Engine: CRI-O v1.31.13
• NIC for FH: Intel Corporation Ethernet Network Adapter E810-XXV-2
• CNI: Cilium (primary), Multus + SR-IOV network device plugin (FH)

Components:

• CU/DU: srsRAN : softwareradiosystems/srsran-project:release_avx512-11c9bbabb6__2025-09-15
• O-RU: LiteOn : 02.00.09

Expected Behavior

• srsRAN container establishes FH connection via SR-IOV interface and receives traffic from O-RU.

Actual Behavior

• SR-IOV interface attaches to container successfully
• FH connection fails to establish
• Small RX traffic from O-RU detected at gNodeB, despite TX traffic present (~800Mbps)

Reproduction Steps

1. Apply SR-IOV Node Policy
2. Attach SR-IOV network to srsRAN container
3. Start srsRAN CU/DU

Configuration Files

srsRAN Configuration (generated by entrypoint.sh inside container)

• Full : config.txt
• O-RU Section

  ru_ofh:
    t1a_max_cp_dl: 350
    t1a_min_cp_dl: 200
    t1a_max_cp_ul: 350
    t1a_min_cp_ul: 200
    t1a_max_up: 300
    t1a_min_up: 0 #0
    ta4_max: 500
    ta4_min: 0
    is_prach_cp_enabled: true
    ignore_ecpri_payload_size: false
    ignore_ecpri_seq_id: true
    compr_method_ul: bfp
    compr_bitwidth_ul: 9
    compr_method_dl: bfp
    compr_bitwidth_dl: 9
    compr_method_prach: bfp
    compr_bitwidth_prach: 9
    enable_ul_static_compr_hdr: true
    enable_dl_static_compr_hdr: true
    iq_scaling: 5.0
    cells:
      - network_interface: 0000:ca:01.4
        ru_mac_addr: 00:aa:ff:bb:ff:cc
        du_mac_addr: 02:9b:7b:1d:50:5e
        vlan_tag_cp: 6                   # VLAN tag value for CP. Note: no need to configure VLAN on NIC
        vlan_tag_up: 6                   # VLAN tag value for UP. Note: no need to configure VLAN on NIC
        prach_port_id: [4, 5, 6, 7]               # eAxCID for PRACH
        dl_port_id: [0, 1, 2, 3]               # eAxCID for DL, length of dl_port_id corresponds to nof_antennas_dl
        ul_port_id: [0, 1, 2, 3]                  # eAxCID for UL, length of ul_port_id corresponds to nof_antennas_ul
    
  

O-RU Configuration

Band Width = 100000000
Center Frequency = 3749700000
Compression Bit = 9
Control and User Plane vlan = 6
M Plane vlan = 0
default gateway = 
dpd mode : Enable
DU MAC Address = 029b7b1d505e
phase compensation mode : Enable
RX attenuation = 14
TX attenuation = 24
subcarrier spacing = 1
rj45_vlan_ip = 10.101.131.61
SFP_vlan_ip = 10.101.131.62
SFP_non_vlan_static_ip = 192.168.1.100
prach eAxC-id port 0, 1, 2, 3 = 0x0004, 0x0005, 0x0006, 0x0007
slotid = 0x00000000
jumboframe = 0x00000001
sync source : PTP

SRIOV Policy

apiVersion: sriovnetwork.openshift.io/v1
kind: SriovNetworkNodePolicy
metadata:
  name: sriov-srsran-cplane
  namespace: sriov-network-operator
spec:
  resourceName: sriov_srsran_uplane
  nodeSelector:
    feature.node.kubernetes.io/network-sriov.capable: "true"
  priority: 13
  deviceType: vfio-pci
  isRdma: false
  numVfs: 6
  mtu: 9216
  linkType: eth
  nicSelector:
    pfNames:
      - 'ens7f0#4-5'
    rootDevices:
      - '0000:ca:00.0'

Additional Info

LiteOn Sync Status

srsRAN Container Stdout

Using resource environment variable: PCIDEVICE_OPENSHIFT_IO_SRIOV_SRSRAN
Updated hal.eal_args CPU list to: 6,8,10,12,14,16,18,20,22,24,29,31
For BDF 0000:ca:01.4, MAC: 02:9b:7b:1d:50:5e
Configuration file updated and placed in /tmp/gnb-config.yml
EAL: Detected CPU lcores: 32
EAL: Detected NUMA nodes: 1
EAL: Detected shared linkage of DPDK
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'PA'
EAL: VFIO support initialized
EAL: Using IOMMU type 1 (Type 1)
IAVF_DRIVER: iavf_configure_queues(): request RXDID[22] in Queue[0]

srsRAN Container Log

• Full: gnb.log
• N-10 Line:

  2025-10-21T06:38:37.633037 [DU-F1   ] [I] Tx PDU du=0 tid=0: F1SetupRequest
  2025-10-21T06:38:37.633117 [CU-CP-F1] [I] Rx PDU du=0 tid=0: F1SetupRequest
  2025-10-21T06:38:37.633201 [CU-CP-F1] [I] Tx PDU du=0 tid=0: F1SetupResponse
  2025-10-21T06:38:37.633209 [DU-F1   ] [I] Rx PDU du=0 tid=0: F1SetupResponse
  2025-10-21T06:38:37.633214 [DU-F1   ] [I] F1 Setup: Procedure completed successfully.
  2025-10-21T06:38:37.633223 [SCHED   ] [I] [     0.0] cell=0: Cell scheduling was activated.
  2025-10-21T06:38:37.633229 [MAC     ] [I] [     0.0] cell=0: Cell was activated
  2025-10-21T06:38:37.633243 [DU-MNG  ] [I] DU manager started successfully.
  2025-10-21T06:38:37.633244 [DU      ] [I] DU-High started successfully
  2025-10-21T06:38:37.633247 [DU      ] [I] DU started successfully
  2025-10-21T06:38:37.633249 [OFH     ] [I] Starting the operation of the Open Front
  
  

SR-IOV interfaces

Monitored Traffic on SR-IOV Interface