Case 4: nCell-T5000 +EU+RU4240 - UDP DL Low Throughput

Equipment: nCell-T5000 +EU+RU4240
Version: BBU: 5GNR_ax.tdd.fr1.2.2.3_422_r50381_i19_20221028_085555+EU:
V0.05.05+RRU:V0.05.05+Acceleration Card：FGAF2.2.0_220811_R

Networking:

Issue Description:
Run Iperf test from Core server after network setup done and UE registered, both TCP and UDP Downlink speed is
limited at around 500Mbps, PDSCH schedule times is low.Iperf test for DL TCP:

Iperf test for DL UDP:

Suggested Troubleshooting Methods:
Check why the RB dispatch is low:
a. Check if the radio environment good.
b. Check if signed AMBR and QCI is restricted.
c. Check if income traffic insufficient.
d. Check if MAC/RLC/PDCP Layer issue

Troubleshooting Procedures:

Padding traffic at air interface, it can reach more than 800Mbps and the scheduled times is full.

Check the AMBR and QCI of UE, maximum 5Gbps and 5QI-9, no restriction.

Check the Tx/Rx speed rate of interface in Iperf server and gNB, it shows the income traffic is sufficient and

Iperf server N6/N3 interface:

gNB N3 Interface:

Check the PDCP layer throughput, it’s same with MAC layer. Check the user-plane data and see there is a lot UDP data stacking which is not extracted, suspect CPU core assignment improperly.

Check the Core Assignment files (CoreAssignment.conf 、 protStackCfg.sh 、 dataplane_env) under
/opt/bbu/oam/cm, it’s not correct. Modify those files as per below:
Modify “CoreAssignment.conf”

Modify “dataplane_env”

Modify “protStackCfg.sh”

Restart protocol stack and disable the switch of security and integrity, restart UE and do iperf test again,
dispatch is full and both tcp&udp throughput improved.

Conclusion:
a. Security and integrity impacts throughput, need be disabled.
b. CPU core assignment issue impact RB dispatch, related core files (CoreAssignment.conf、protStackCfg.sh、dataplane_env)need be aligned as per latest solution.

 Troubleshooting Methods: Download