4G Failure in radio interface procedure cause value 26

4G LTE
1

Hello,

What are causes for this failure cause value? (failure in radio interface procedure cause value 26)

2

Possible radio link failures( check AbnormRel.RNL if increase ).

Actually the main root cause seems that UE not reply to Security Mode Command and UuMessageWaitingTimer expired (Check value of timer)

From Trace ,enodeB send S1AP:InitialContextSetupFailure with value Cause : failure-in-radio-interface-procedure and then Call Drop will increase.

Note:Increased UuMessageWaitingTimer gives UE more time to finish RRC procedure – lower probability of abnormal eNB release

1 Like
3

indeed UE is not replying to security command but uu timer is at 35secs.

What is its due to
image

which command can show the allowed encryption algorithms of the enodeB.

4

Below command

Integrity protection algorithm
Integrity protection algorithm904×211 3.86 KB

Ciphering algorithm
Ciphering algorithm900×187 3.62 KB

Trace

LST ENODEBINTEGRITYCAP:

PrimaryIntegrityAlgo=AES, SecondIntegrityAlgo=Snow3G, ThirdIntegrityAlgo=ZUC, NullAlgo=Enable;

LST ENODEBCIPHERCAP

PrimaryCipherAlgo=AES, SecondCipherAlgo=Snow3G, ThirdCipherAlgo=ZUC, FourthCipherAlgo=NULL;

Counter to check Failure:Number of security mode configuration failures received from the UE [L.SecurMode.Fail]

5

L.SecurMode.Fail this counter is for Huawei OEM do have similar counter for other OEM’s.