AMF Returns ABORT in Response to SCTP INIT

I have installed Free5GC (version 3.1.0) in a VM (Ubuntu 20.04 kernel 5.13.0) created in Microsoft Azure Cloud. Free5GC-gnb has been installed on-premise in my lab. The core and gNB have been communicating with public IP through firewall. However, as soon as we run nr-gnb, AMF sends SCTP Abort. No reason has been given. The following shows the packet capture at gNB and core. The configs are also shown below.

root@ueransim:/opt/free5gc-RAN/UERANSIM# build/nr-gnb -c config/free5gc-gnb.yaml
UERANSIM v3.1.0
[2022-06-10 13:55:56.989] [sctp] [info] Trying to establish SCTP connection… (23.100.16.239:38412)
[2022-06-10 13:55:57.021] [sctp] [error] Connecting to 23.100.16.239:38412 failed. SCTP could not connect: Connection refused

root@ueransim:/opt/free5gc-RAN/UERANSIM/config# tcpdump -ni ens4
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ens4, link-type EN10MB (Ethernet), capture size 262144 bytes
13:55:56.992295 IP 192.168.163.244.49715 > 23.100.16.239.38412: sctp (1) [INIT] [init tag: 2806966459] [rwnd: 106496] [OS: 10] [MIS: 10] [init TSN: 1928839303]
13:55:57.002754 IP 23.100.16.239.38412 > 192.168.163.244.49715: sctp (1) [ABORT]
13:55:57.002836 IP 192.168.163.244.49715 > 23.100.16.239.38412: sctp (1) [INIT] [init tag: 428888311] [rwnd: 106496] [OS: 10] [MIS: 10] [init TSN: 2163775967]
13:55:57.012102 IP 23.100.16.239.38412 > 192.168.163.244.49715: sctp (1) [ABORT]
13:55:57.012157 IP 192.168.163.244.49715 > 23.100.16.239.38412: sctp (1) [INIT] [init tag: 323922057] [rwnd: 106496] [OS: 10] [MIS: 10] [init TSN: 2527221338]
13:55:57.021353 IP 23.100.16.239.38412 > 192.168.163.244.49715: sctp (1) [ABORT]

root@ueransim:/opt/free5gc-RAN/UERANSIM/config# cat free5gc-gnb.yaml
mcc: ‘208’ # Mobile Country Code value
mnc: ‘93’ # Mobile Network Code value (2 or 3 digits)

nci: ‘0x000000010’ # NR Cell Identity (36-bit)
idLength: 32 # NR gNB ID length in bits [22…32]
tac: 1 # Tracking Area Code

linkIp: 192.168.163.244 # gNB’s local IP address for Radio Link Simulation (Usually same with local IP)
ngapIp: 192.168.163.244 #`gNB’s local IP address for N2 Interface (Usually same with local IP)
gtpIp: 192.168.163.244 # gNB’s local IP address for N3 Interface (Usually same with local IP)

List of AMF address information

amfConfigs:

  • address: 23.100.16.239

: 10.5.163.4

port: 38412

List of supported S-NSSAIs by this gNB

slices:

  • sst: 0x1
    sd: 0x010203

Indicates whether or not SCTP stream number errors should be ignored.

ignoreStreamIds: true

root@5GC-CORE-VM-tc2762:/opt/free5gc# tcpdump -ni eth3
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth3, link-type EN10MB (Ethernet), capture size 262144 bytes
13:55:56.996961 IP 12.234.208.124.49715 > 10.5.163.4.38412: sctp (1) [INIT] [init tag: 2806966459] [rwnd: 106496] [OS: 10] [MIS: 10] [init TSN: 1928839303]
13:55:56.997029 IP 10.5.163.4.38412 > 12.234.208.124.49715: sctp (1) [ABORT]
13:55:57.006601 IP 12.234.208.124.49715 > 10.5.163.4.38412: sctp (1) [INIT] [init tag: 428888311] [rwnd: 106496] [OS: 10] [MIS: 10] [init TSN: 2163775967]
13:55:57.006649 IP 10.5.163.4.38412 > 12.234.208.124.49715: sctp (1) [ABORT]
13:55:57.015915 IP 12.234.208.124.49715 > 10.5.163.4.38412: sctp (1) [INIT] [init tag: 323922057] [rwnd: 106496] [OS: 10] [MIS: 10] [init TSN: 2527221338]
13:55:57.015949 IP 10.5.163.4.38412 > 12.234.208.124.49715: sctp (1) [ABORT]

root@5GC-CORE-VM-tc2762:/opt/free5gc# more config/amfcfg.yaml
info:
version: 1.0.3
description: AMF initial local configuration

configuration:
amfName: AMF # the name of this AMF
ngapIpList: # the IP list of N2 interfaces on this AMF
- 23.100.16.239
# - 10.5.163.4
sbi: # Service-based interface information
scheme: http # the protocol for sbi (http or https)
registerIPv4: 10.5.20.18 # IP used to register to NRF
bindingIPv4: 10.5.20.18 # IP used to bind the service
port: 8000 # port used to bind the service
tls: # the local path of TLS key
pem: config/TLS/amf.pem # AMF TLS Certificate
key: config/TLS/amf.key # AMF TLS Private key
serviceNameList: # the SBI services provided by this AMF, refer to TS 29.518
- namf-comm # Namf_Communication service
- namf-evts # Namf_EventExposure service
- namf-mt # Namf_MT service
- namf-loc # Namf_Location service
- namf-oam # OAM service
servedGuamiList: # Guami (Globally Unique AMF ID) list supported by this AMF
# =
- plmnId: # Public Land Mobile Network ID, =
mcc: 208 # Mobile Country Code (3 digits string, digit: 0~9)
mnc: 93 # Mobile Network Code (2 or 3 digits string, digit: 0~9)
amfId: cafe00 # AMF identifier (3 bytes hex string, range: 000000~FFFFFF)
supportTaiList: # the TAI (Tracking Area Identifier) list supported by this AMF
- plmnId: # Public Land Mobile Network ID, =
mcc: 208 # Mobile Country Code (3 digits string, digit: 0~9)
mnc: 93 # Mobile Network Code (2 or 3 digits string, digit: 0~9)
tac: 1 # Tracking Area Code (uinteger, range: 0~16777215)
plmnSupportList: # the PLMNs (Public land mobile network) list supported by this AMF
- plmnId: # Public Land Mobile Network ID, =
mcc: 208 # Mobile Country Code (3 digits string, digit: 0~9)
mnc: 93 # Mobile Network Code (2 or 3 digits string, digit: 0~9)
snssaiList: # the S-NSSAI (Single Network Slice Selection Assistance Information) list supported by this AMF
- sst: 1 # Slice/Service Type (uinteger, range: 0~255)
sd: 010203 # Slice Differentiator (3 bytes hex string, range: 000000~FFFFFF)
- sst: 1 # Slice/Service Type (uinteger, range: 0~255)
sd: 112233 # Slice Differentiator (3 bytes hex string, range: 000000~FFFFFF)
supportDnnList: # the DNN (Data Network Name) list supported by this AMF
- internet
nrfUri: http://10.5.20.10:8000 # a valid URI of NRF
security: # NAS security parameters
integrityOrder: # the priority of integrity algorithms
- NIA2
# - NIA0
cipheringOrder: # the priority of ciphering algorithms
- NEA0
# - NEA2
networkName: # the name of this core network
full: free5GC
short: free
locality: area1 # Name of the location where a set of AMF, SMF and UPFs are located
networkFeatureSupport5GS: # 5gs Network Feature Support IE, refer to TS 24.501
enable: true # append this IE in Registration accept or not
length: 1 # IE content length (uinteger, range: 1~3)
imsVoPS: 0 # IMS voice over PS session indicator (uinteger, range: 0~1)
emc: 0 # Emergency service support indicator for 3GPP access (uinteger, range: 0~3)
emf: 0 # Emergency service fallback indicator for 3GPP access (uinteger, range: 0~3)
iwkN26: 0 # Interworking without N26 interface indicator (uinteger, range: 0~1)
mpsi: 0 # MPS indicator (uinteger, range: 0~1)
emcN3: 0 # Emergency service support indicator for Non-3GPP access (uinteger, range: 0~1)
mcsi: 0 # MCS indicator (uinteger, range: 0~1)
t3502Value: 720 # timer value (seconds) at UE side
t3512Value: 3600 # timer value (seconds) at UE side
non3gppDeregistrationTimerValue: 3240 # timer value (seconds) at UE side

retransmission timer for paging message

t3513:
enable: true # true or false
expireTime: 6s # default is 6 seconds
maxRetryTimes: 4 # the max number of retransmission

retransmission timer for NAS Deregistration Request message

t3522:
enable: true # true or false
expireTime: 6s # default is 6 seconds
maxRetryTimes: 4 # the max number of retransmission

retransmission timer for NAS Registration Accept message

t3550:
enable: true # true or false
expireTime: 6s # default is 6 seconds
maxRetryTimes: 4 # the max number of retransmission

retransmission timer for NAS Authentication Request/Security Mode Command message

t3560:
enable: true # true or false
expireTime: 6s # default is 6 seconds
maxRetryTimes: 4 # the max number of retransmission

retransmission timer for NAS Notification message

t3565:
enable: true # true or false
expireTime: 6s # default is 6 seconds
maxRetryTimes: 4 # the max number of retransmission

retransmission timer for NAS Identity Request message

t3570:
enable: true # true or false
expireTime: 6s # default is 6 seconds
maxRetryTimes: 4 # the max number of retransmission

the kind of log output

debugLevel: how detailed to output, value: trace, debug, info, warn, error, fatal, panic

ReportCaller: enable the caller report or not, value: true or false

logger:
AMF:
debugLevel: debug #info
ReportCaller: true # false
NAS:
debugLevel: info
ReportCaller: false
FSM:
debugLevel: info
ReportCaller: false
NGAP:
debugLevel: debug #info
ReportCaller: false
Aper:
debugLevel: info
ReportCaller: false

Hi @tarunch1k,
It seems both of your configurations are fine.
Is there any error log in free5GC?

Hi, @tarunch1k
since there hasn’t been any replies from you, this topic is closed by admin.
If you have further questions about this topic, please create another topic.
Thanks.