Case25: 4G T4000 SCTP Link Instable

Equipment: T4000 Version: BBU_V100R009C00SP058

1. Issue Description

After add permanet route in script “/appfs/bbu/rootfs/bts/scripts/rootfs_start.sh” and reboot to valid the change. eNB shows S1 link interrupt alarm, and it keeps connect and disconnect, cell status also keeps changing between forbid and normal.

Soft reboot in webgui has same apperance.

2. Troubleshooting

Collect the tcpdump from eNB and see eNB shutdown the S1 link actively and sends “Abort”, check the cause and see “ Asscociation exceeded its max_retrans_ count"

Check the Sctp link parameter for timeout and retransmit times, it’s small and need be adjusted. Maximum Retransmission Timeout(millisecond)=500

Maximum Retransmission Times=3

Max Association Retransmits=2

Life cvcle of Valid cookies=5000

3. Solution Adjust the SCTP link parameter as below and S1 link is stable.

Troubleshooting Methods: Download