[srslte-users] service reject error

[J Giovatto]

Hi,

Yes it works |

Setting the channel emulator for the ue.

[channel.dl.rlf]
enable        = true
t_on_ms       = 45000
t_off_ms      = 45000


Current sample rate is 11.52 MHz with a base rate of 23.04 MHz (x2
decimation)
Current sample rate is 11.52 MHz with a base rate of 23.04 MHz (x2
decimation)
Random Access Transmission: seq=14, tti=8831, ra-rnti=0x2
RRC Connected
Random Access Complete.     c-rnti=0x48, ta=0
Service Request successful.

Now a running ping will re-establish the link and continue !

Thanks
Joe


On 6/8/21 12:14 PM, Pedro Alvarez wrote:
> Hi Joe --
>
> Thanks a lot for reporting this. I think the issue here is in the way
> the short MAC integrity is calculated at the MME.
> Basically, the MME (and the UE) need to keep an NAS COUNT, which can
> be decomposed into an overflow counter (16 most significant bits) and
> an NAS sequence number (8 least significant bits).
>
> To check the integrity we should do the following, see section 4.4.3.3:
>
>> The receiver shall use the NAS sequence number included in the received message (or estimated from the 5 bits of the
>> NAS sequence number received in the message) and an estimate for the NAS overflow counter as defined in
>> subclause 4.4.3.1 to form the NAS COUNT input to the integrity verification algorithm.
> We correctly used the received sequence number in the normal integrity
> protection checks, but it seems that the short integrity check is
> incorrect.
> Could you try the attached patch?
>
> On Mon, Jun 7, 2021 at 8:33 PM J Giovatto <jgiovatto at adjacentlink.com> wrote:
>> Hi Folks
>>
>> I was wondering if anyone else has seen this...
>>
>> To reproduce:
>>
>> 1) with a "ping 172.16.0.101 -p aa" running to the epc, break rf link
>> between established ue/enb pair to the epc for 2 minutes or more.
>>
>> 2) re-establish rf link, ping completion never resumes.
>>
>>
>> Log highlights below...
>>
>> epc log ==================================
>>
>> 18:24:17.322551 [NAS    ] [W] Short integrity check failure. Local:
>> count=3, [88 0d ae 3c], Received: count=6, [75 06]
>>
>> ue log ===================================
>>
>> 18:24:17.328535 [NAS    ] [I] Received service reject with EMM cause=0x9
>> and t3446=0
>>
>> 18:24:18.109605 [RLC    ] [I] SRB1 SN=0 outside rx window [1:513] - AM
>> discarding
>>
>> enb log ==================================
>>
>> 8:24:17.323345 [PDCP   ] [I] TX SRB1 PDU, SN=0, integrity=none,
>> encryption=none
>>
>> Thanks
>>
>> Joe
>> _______________________________________________
>> srslte-users mailing list
>> srslte-users at lists.softwareradiosystems.com
>> https://lists.softwareradiosystems.com/mailman/listinfo/srslte-users



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