Fetching the Target eNB based on the Target en-gNB ID without TAC

Feature Summary and Revision History

Summary Data

Applicable Product(s) or Functional Area

MME

Applicable Platform(s)

  • ASR 5500

  • VPC-DI

Feature Default

Enabled - Always-On

Related Changes in This Release

Not Applicable

Related Documentation

MME Administrartion Guide

Revision History

Revision Details

Release

MME supports fetching target eNodeB based on the en-gNB-ID without TAC. For more information, see the MME Support for EN-DC SON Configuration Transfer IE on S1-AP chapter in the MME Administration Guide.

  • 2024.2.0

  • 21.28.m5

Feature Description

In some scenarios, when the UE moves to a coverage of en-gNB, which is not added as secondary node to the eNodeB, but the UE is presently connected to eNodeB uses ANR procedures to add en-gNB as secondary node and send the ENB CONFIGURATION TRANSFER message to the MME. Currently eNodeB may not send the right Tracking Area Update (TAC) in the selected TAI of target en-gNB. This mapping of eNodeB to en-gNB id with PLMN and TAC in MME could result in secondary node addition failure.

To overcome this scenario, MME supports seamless mobility between two gNBs connected with eNodeBs in the same or different TACs. MME maps eNodeB to en-gNB ID plus bPLMN received in the S1 setup and eNodeB Configuration Update requests. Thus the en-gNB ID and PLMN key fetch target eNodeB connected to target en-gNB ID seamlessly. If a multiple target eNodeB ID matches, the first available eNodeB with the association state in MME as UP is selected.