· The PDN connectivity procedure is used by the UE to request the setup of a default EPS bearer to a PDN.
· The UE requests connectivity to a PDN by sending a PDN CONNECTIVITY REQUEST message to the network. If this request is accepted by the network, then it initiates the establishment of a default EPS bearer context activation procedure.
· This procedure is used either to establish the first default bearer (PDN CONNECTIVITY REQUEST is sent along with initial attach message), or to establish subsequent default bearers to additional PDNs (a stand-alone PDN CONNECTIVITY REQUEST is sent by the UE).
· If the UE is in EMM-IDLE mode, the Service Request procedure is performed before the PDN Connectivity procedure can be initiated.
· If there is already a PDN connection for emergency bearer services established, the UE shall not request an additional PDN connection for emergency bearer services.
· A UE attached for emergency bearer services shall not request a PDN connection to any other PDN.
· When the PDN CONNECTIVITY REQUEST message is sent together with an ATTACH REQUEST message, the UE shall not include the APN.
· When requesting connectivity to an additional PDN, the UE shall include the requested APN (in the stand-alone PDN CONNECTIVITY REQUEST) except for emergency bearer services
· The UE may set the ESM information transfer flag in the PDN CONNECTIVITY REQUEST message to indicate that it has ESM information, i.e. protocol configuration options, or APN, or both, that needs to be transferred to the MME after the NAS signalling security has been activated
· If the ESM information transfer flag is set in PDN CONNECTIVITY REQUEST message, the MME initiates (after NAS sigalling security is activated) the ESM information request procedure in which the UE can provide the MME with protocol configuration options or APN or both.
· If the UE wishes to connect to a PDN using default APN, it need not include the APN in the Access Point Name IE in the ESM INFORMATION RESPONSE or PDN CONNECTIVITY REQUEST (stand-alone) message. The only exceptional case is, if the connectivity to a PDN using the default APN requires PAP/CHAP, then the UE should include the APN in the Access point name IE
· The UE shall set the Request Type IE to "initial request" when the UE is establishing a new PDN connectivity to a PDN in an attach procedure or in a stand-alone PDN connectivity procedure.
· The UE shall set the Request Type IE to "emergency" when the UE is requesting a new PDN connectivity for emergency bearer services.
· The Request Type IE is set to "handover" when the connectivity to a PDN is established upon handover from a non-3GPP access network and the UE was connected to that PDN before the handover to the 3GPP access network
· The other IEs in the PDN CONNECTIVITY REQUEST message include EPS Bearer Identity, Procedure Transaction Identity, PDN Type, and Device Properties etc…
· If the UE includes ESM information transfer flag in the PDN CONNECTIVITY REQUEST message, the MME waits for completion of the ESM information request procedure before proceeding with the PDN connectivity procedure. The MME then checks if connectivity with the requested PDN can be established.
· If requested APN is not included in the PDN CONNECTIVITY REQUEST or the ESM INFORMATION RESPONSE message and the request type is different from "emergency", the MME shall use the default APN as the requested APN. If the request type is "emergency", the MME shall use the APN configured for emergency bearer services
Reference 3GPP TS 24.301
Example1: PDN CONNECTIVITY REQUEST message (sent along with Attach Request)
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Example2: Stand-Alone PDN CONNECTIVITY REQUEST message
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Hi,
ReplyDeleteIn Attach accept Msg. we will get PDN Ip address, so where UE is get its own IP address. Or that address is the UE IP address.
Can u please explain it
Thanks
Sandeep
Hi Sandeep,
DeleteAttach accept NAS message contains the APN name and PDN address. Apn name indicates for which PDN, UE is attached and PDN address is the UE IP address assigned by the APN.
Regards,
Ashwin.
Hi, how does network knows specificaly what type of data the ue requesting in initial request. Network need to know this for obtaining corresponding qci from qci mapping in pcrf for erab setup. Say example how it knows if ue requesting service for web browsing or ftp download? Assuming only one Apn exist in operator's network.
ReplyDeleteDefault EPS Bearer is pre-configured with standard QoS so it doesn't matter what application UE is accessing, of application specific QoS addition Network Function (Application Detection Function) is needed, this connects to PCRF via Sd interface, letś say you want to assign guaranteed bit rates to a NetFlix app, then Application Detection Function will detect Netflix based on config, then request for additional QoS to PCRF which will install Rule to PCEF for that appication etc. I hope this helps
DeleteHi, I notice that there is an APN configured in my handset (UE). Is this the default APN? When is it being used?
ReplyDeleteIs there any time period after which PDN connectivity request is sent??
ReplyDeleteOnce QCI5 is removed, UE do not send PDN connectivity request after voice call initiation, is it UE fault or there is any timer after which only UE can send PDN connectivity request for QCI5??
Hi All, I have Basic Question, Why are we sending PDN connection req when we are doing Attach?
ReplyDeleteHi,
ReplyDeleteI have a question. I have not configured my additional APN in IMSI's APN configuration as well as on HSS's APN Configuration. After initial attach with one default APN, my UE is requesting to create another PDN connection with this APN not configured(the same APN is known to MME's PGW Configuration and is also configured at PGW). The UE is able to attach with DIAMETER_UNABLE_TO_COMPLY in Notify Answer message from HSS->MME. There is no message exchange between MME and HSS in additional PDN connection, but still in Create Session Request from SGW->PGW, "Selection Mode : MS or n/w provided APN, subscribed verified" is there. Please explain. How?
I'm facing one issue during my test. Attach fail with eMM-cause:no-Suitable-Cells-In-tracking-area. in the trace there is no messege on S6a interface. so it mean that request is rejected by MME. could you please assist me to find the reason ?
ReplyDeletecan you please share 3gpp spec ref where below thing is mentioned:
ReplyDeleteWhen the PDN CONNECTIVITY REQUEST message is sent together with an ATTACH REQUEST message, the UE shall not include the APN.
I tried looking into PDN Connectivity Request message in ETSI TS 124 244 and ETSI TS 124 008 but I can not find when APN info shall be included in PDN connectivity request and when it shouldn't. Can you please help ?
Please check 24.301 section 6.5.1.2
Deletecan u share ur mail id need to discuss
ReplyDeleteFrom wireshark traces how can i find the number of PDN connections that exist after MME initiated dettach
ReplyDeleteSir
ReplyDeleteThe information provided by is so much helpful .
Can please explain after ,
Initial UE msg(Attach request ,PDN connectivity request)
UE to eNB
Rcc connection req ->
<-Rcc connection setup
Rcc connection setup complete +Nas attach req ->
Initial UE msg(Attach request ,PDN connectivity request) after this procedure
hie kumar,
ReplyDeleteif possible upload some ims stuff.
thank you somuch for ur blog..
its very useful.
Hi All,
ReplyDeletethere is no response from the below IMS PDN connectivity request from the n/w hence IMS registration is not getting triggered. What could be the possible reason for this. Do i need to see why there is response from n/w side on PDN connectivity request.
For example:-
[0xB0E3] OTA LOG 01:24:11.636311 LTE NAS ESM Plain OTA Outgoing MessagePDN connectivity request Msg1 0
[0xB0E3] OTA LOG 01:24:13.920022 LTE NAS ESM Plain OTA Outgoing MessagePDN connectivity request Msg1 0
[0xB0E3] OTA LOG 01:24:19.636426 LTE NAS ESM Plain OTA Outgoing MessagePDN connectivity request Msg1 0
[0xB0E3] OTA LOG 01:24:21.929188 LTE NAS ESM Plain OTA Outgoing MessagePDN connectivity request