Network Triggered Dedicated Bearer Creation

Question

I have a query related to Dedicated Bearer Creation.

If two UEs are attached to the network and if network is triggering the Dedicated Bearer Creation, how network identifies for which UE it has to create the Dedicated Bearer. Because as part of Create Bearer Request that is from PGW-SGW-MME we are no where specifying the IMSI value or something else related to UE. So how will network identify the UE and initiate the Bearer Creation.?

Comments

Commented on behalf of Sheetala Suaro (https://www.facebook.com/groups/LTE.Professionals )
UE IP Address is the identifier

Answer 1

The MME-UE-S1AP-ID and eNB-UE-S1AP-ID are unique to every UE so based on that the network can easily identify the UE.
Also if you see the "ERAB to be setup" you can see the TMSI/P-TMSI for that particular UE

Answer 2

I would like to add few points here. LTE core network has so many nodes likes MME, SGW, PGW/PCEF, PCRF, AF , SPR/HSS . Here when we talk about network initiated it means, Application function is initiating. AF triggers control message to PCRF for an UE and then PCRF sends diameter RAR message to PCEF. PCEF/PGW sits together so once PCEF receives message from PCRF, PGW sends create initiates "create bear request" to SGW and SGW forwards this message to MME. Please go through 3GPP 29.212 and 29.214 specifications. There is a "Subscription-Id " AVP which is used to carry UE subscription related informations like IMSI, MSISDN number in both Rx (interface between PCRF<->AF) and Gx (interface between PRCF and PCEF).