AMF not connecting with gNB

fefer · March 22, 2021, 2:42pm

Hi all,

I am trying to connect free5GC with a Nokia Airscale, but I am getting some strange problems regarding the AMF connection. I am attaching the configs and logs. Can someone help me? Below is the atchitecture overview:

free5gc(sa)

free5gc.7z (76.2 KB)

free5GC · March 22, 2021, 2:42pm

Hi,
The error seems like encounter some TA things:

time="2020-11-25T12:00:19-03:00" level=error msg="Registration Reject[Tracking area not allowed]" category=Gmm component=AMF

Does the TAC in the RAN same as TAC on AMF’s config?

fefer · March 22, 2021, 2:42pm

Yes, they are both set for 8101. Attached the output of Nokia gNB.

free5GC · March 22, 2021, 2:42pm

Is your NRF running?

fefer · March 22, 2021, 2:42pm

Thank you for your answer!
You are right, the NRF was not running. Now its running, but still no progress from the gNB side, I am sending the SCTP but an abort message is sent from the core side. Attached the new logs

free5gc.7z (79.7 KB)

free5GC · March 22, 2021, 2:42pm

Is it possible to provide some pcap file?

There is also some address error on the new output file, may you check on it?

fefer · March 22, 2021, 2:42pm

Sure, I have changed the AMF config and now the SCTP seems to be much better. However, now I am getting the following error:

2020-12-11T07:25:31-03:00 [ERRO][AMF][NGAP] Build NGSetupResponse failed : OctetString Length is over upperbound (/home/free5gc/free5gc/src/amf/ngap/message/send.go:87 free5gc/src/amf/ngap/message.SendNGSetupResponse)

Attached the logs, unfortunately the pcap is too big to upload a bit more than 4.5MB zipped, I am sending two links (one more alternativa) with the pcap:

https://app.boxcn.net/s/vjkvjb5bfdleiaq5crbywkeb4ngkhwgc

free5GC · March 22, 2021, 2:42pm

The google drive’s link is not accessible.

fefer · March 22, 2021, 2:42pm

Quick update, I was able to get through by setting the sd as an hexadecimal (D143A5). However, something strange happened after it, the first time the AMF blinked on the gNB side and I got a lot of messages after the SCTP accept, I have saved the output as “output.txt”, unfortunately I was not able to pick up this specific pcap. Then, I tried to run it again and the output was different, I got stuck at the SCTP accept, this one I was able to save the pcap and the output as “output2.txt”, all files are attached. Can you guys help me? I am feeling we are getting really near an integration between them.

free5gc.zip (217.9 KB)

calee · March 22, 2021, 2:42pm

On the pcap file, after RAN send SCTP COOKIE_ACK, it keep sending HEARTBEAT but not sending NGSetup Request.

The heartbeat seems fine, but I’m not sure why your RAN didn’t start to do the ng setup procedure. Maybe you should re-start your RAN?

calee · March 22, 2021, 2:42pm

On your first output, it crash on

github.com

free5gc/amf/blob/be39ddb6b976d436e7b9d8e32495fcfd9b8b7e00/ngap/handler.go#L3337


		case ngapType.ProtocolIEIDDefaultPagingDRX:
			pagingDRX = ie.Value.DefaultPagingDRX
			if pagingDRX == nil {
				logger.NgapLog.Error("PagingDRX is nil")
				return
			}
			logger.NgapLog.Tracef("[NGAP] Decode IE PagingDRX = [%d]", pagingDRX.Value)
		}
	}
	for i := 0; i < len(supportedTAList.List); i++ {
		supportedTAItem := supportedTAList.List[i]
		tac := hex.EncodeToString(supportedTAItem.TAC.Value)
		capOfSupportTai := cap(ran.SupportedTAList)
		for j := 0; j < len(supportedTAItem.BroadcastPLMNList.List); j++ {
			supportedTAI := context.NewSupportedTAI()
			supportedTAI.Tai.Tac = tac
			broadcastPLMNItem := supportedTAItem.BroadcastPLMNList.List[j]
			plmnId := ngapConvert.PlmnIdToModels(broadcastPLMNItem.PLMNIdentity)
			supportedTAI.Tai.PlmnId = &plmnId
			capOfSNssaiList := cap(supportedTAI.SNssaiList)

I suppose that supportedTAList.List is null, may you help to check if these lines has been successfully jump into?

github.com

free5gc/amf/blob/be39ddb6b976d436e7b9d8e32495fcfd9b8b7e00/ngap/handler.go#L3320-L3326


		case ngapType.ProtocolIEIDSupportedTAList:
			supportedTAList = ie.Value.SupportedTAList
			logger.NgapLog.Trace("[NGAP] Decode IE SupportedTAList")
			if supportedTAList == nil {
				logger.NgapLog.Error("Supported TA List is nil")
				return
			}

Maybe when the ConfigurationUpdate didn’t update SupportedTAList, free5GC didn’t welly handle the message.

Sabbir89 · March 22, 2021, 2:42pm

Hi,

Is this issue solved by @fefer or something by free5GC? Curious because I am going to have Airscale gNB most probably in next week and thinking of using the core to be used, free5GC or Open5GS. Thanks

BR,
Sabbir

fefer · March 22, 2021, 2:42pm

Hi Sabbir,

As exposed in this topic, the AMF is up now and all other elements. I am just trying to connect a device there, but still not able, my understanding is that the problem should be on the device side, we are still debugging it. The problem I was having was because I was missing one config. If you have success with Nokia Airscale, please let me know in this topic. I believe I am almost there!

Sabbir89 · March 22, 2021, 2:42pm

Hi Fefer,

Thank you so much for the prompt response. I will share my experience with the test. BTW, have you tried also with the Open5GS 5GC ?

BR,
Sabbir