4G/LTE - NAS |
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ESM Cause - #50, #51, #52
The purpose of the ESM cause information element is to indicate the reason why a session management request (e.g, PDN Connectivity Request) is rejected (e.g, PDN Connectivity Reject) or restricted (e.g, Activate default EPS bearer context request).
NAS Messages Carrying ESM Cause
There are roughly two type of NAS message that carry ESM Cause. One is Activate default EPS Bearer Request which is used to accept the IP that UE requested and another message is PDN Connectivity Reject which is used to reject the PDN that UE requested.
Meaning of the Cause defined in 3GPP
The details of ESM Cause is described in 24.301 B.1 Causes related to Nature of Request
#50, #51, #52 are as follows :
If you expend this table into more detailed cases, we can describe the cases as follows.
Note (*) : "Single Bearer" indicate Network allows 'single address bearer only'.
Also, 24.301 6.2.2 IP address allocation via NAS signalling describes in detail as follows :
Example 1 > i) UE Request IPv4 to Network that support IPv6 only ii) Network send PDN Connectivity Reject with ESM Cause 51
Step 3 : RRC Connection Setup Complete + Attach Request + PDN Connectivity Request
UL-DCCH-Message message: c1 (0) c1: rrcConnectionSetupComplete (4) rrcConnectionSetupComplete rrc-TransactionIdentifier: 0 criticalExtensions: c1 (0) c1: rrcConnectionSetupComplete-r8 (0) rrcConnectionSetupComplete-r8 selectedPLMN-Identity: 1 registeredMME mmegi: 8001 [bit length 16, 1000 0000 0000 0001 decimal value 32769] mmec: 00 [bit length 8, 0000 0000 decimal value 0] dedicatedInfoNAS: 17824a8d76050741220bf61300148001000000000105e060... Non-Access-Stratum (NAS)PDU ..... EPS mobile identity ..... UE network capability ..... ESM message container Length: 33 ESM message container contents: 0202d011d1271a8080211001000010810600000000830600... 0000 .... = EPS bearer identity: No EPS bearer identity assigned (0) .... 0010 = Protocol discriminator: EPS session management messages (0x02) Procedure transaction identity: 2 NAS EPS session management messages: PDN connectivity request (0xd0) 0001 .... = PDN type: IPv4 (1) .... 0001 = Request type: initial request (1) ESM information transfer flag .... Protocol Configuration Options ..... Tracking area identity - Last visited registered TAI ..... DRX Parameter ..... MS Network Capability ..... HEX : 20 20 80 01 00 65 17 82 4A 8D 76 05 07 41 22 0B F6 13 00 14 80 01 00 00 00 00 01 05 E0 60 C0 40 01 00 21 02 02 D0 11 D1 27 1A 80 80 21 10 01 00 00 10 81 06 00 00 00 00 83 06 00 00 00 00 00 0D 00 00 0A 00 52 13 00 14 00 01 5C 0A 00 31 03 E5 E0 3E 13 13 00 14 00 01 11 03 57 58 A6 40 08 04 02 60 00 00 02 1F 00 5D 01 02 E0
Step 7 : dlInformationTransfer+Attach Reject+PDN Connectivity Reject DL-DCCH-Message message: c1 (0) c1: dlInformationTransfer (1) dlInformationTransfer rrc-TransactionIdentifier: 0 criticalExtensions: c1 (0) c1: dlInformationTransfer-r8 (0) dlInformationTransfer-r8 dedicatedInfoType: dedicatedInfoNAS (0) dedicatedInfoNAS: 27cf676073020744137800040202d133 Non-Access-Stratum (NAS)PDU .... NAS EPS Mobility Management Message Type: Attach reject EMM cause Cause: ESM failure (19) ESM message container Element ID: 0x78 Length: 4 ESM message container contents: 0202d133 .... Procedure transaction identity: 2 NAS EPS session management messages: PDN connectivity reject (0xd1) ESM cause Cause: PDN type IPv6 only allowed (51) HEX : 08 00 81 3E 7B 3B 03 98 10 3A 20 9B C0 00 20 10 16 89 98
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