SessMgr SMF Changes

DSCP markings for Uplink/CORE and Downlink/ACCESS are present at bearer level inside sessmgr_sub_session_t → sessmgr_qci_tab_t.

User datagram DSCP markings are updated in IP header of inner packet. That is, packet sent from UE to Internet and the opposite way.

Encaps header DSCP markings are updated in IP header of outer IP layer having GTP-U header (Outer header).

DSCP markings are sent from SMF to UPF inside FAR IE as follows:

  • Transport Level Marking - The DSCP markings is configured in encaps header for ACCESS side and User-datagram on CORE side for collapse call.

  • Transport Level Marking Options—Includes two options and are applicable only for outer header:

    • Copy-inner: Copy the inner packets markings to outer header

    • Copy-outer: Relay the DSCP markings for outer header

Inner Packet Marking—DSCP markings is configured in user datagram for ACCESS side. For CORE side, it’s N/A for collapse call.

Logic to fetch the DSCP marking has changed for collapse call:

  • Fetch the DSCP markings based on QCI and "qrp_pl" for session from the associated SGW Service for ACCESS/downlink side.

  • Fetch the DSCP markings based on QCI and "qrp_pl" for session from the associated PGW Service for CORE/uplink side.

  • For ACCESS/downlink side, QCI-QOS-mapping table associated with APN-profile takes preference over SGW Service QCI-QOS-mapping table.

  • For CORE/uplink side QCI-QOS-mapping table associated with APN config takes preference over PGW Service QCI-QOS-mapping table.

  • In case SGW Service QCI-QOS-mapping table isn’t configured, then PGW Service QCI-QOS-mapping table is applicable on both ACCESS/CORE side.

  • In case PGW Service QCI-QOS-mapping table isn’t configured, then SGW Service QCI-QOS-mapping table is applicable on ACCESS side and no DSCP markings are applicable on CORE side.

  • DSCP markings are updated on UPF in create/update FAR sent as a part of Sx/N4 Establishment/Modification request from SMF to UPF.

  • Update the TLM, IPM, and TLMO in case of HO from Pure-P to Collapse and vice versa in Sx/N4 Modification request as a part of Update FAR IE.

  • Update the Layer2 markings in case of HO from Pure-P to Collapse and vice versa in Sx/N4 Modification request as a part of Update FAR IE.

Following table depicts the various possible config combinations and outcome for DSCP markings to be applied on ACCESS and CORE side for COLLAPSE call:

S. No. Feature Enable / Disable PGW Service QOS-QCI Table Configured (Q1) SGW Service QOS-QCI Table Configured (Q2) APN QOS-QCI Table Configured (Q3) APN-Profile QOS-QCI Table Configured (Q4) ACCESS/Downlink DSCP Markings for Collapse Call CORE/Uplink DSCP Markings for Collapse Call
1 ENABLE YES YES YES YES Q4 (APN-Profile) Q3(APN)
2 ENABLE YES YES YES NO Q2 (SGW-Service) Q3(APN)
3 ENABLE YES YES NO YES Q4 (APN-Profile) Q1 (PGW-service)
4 ENABLE YES YES NO NO Q2 (SGW-Service) Q1 (PGW-service)
5 ENABLE YES NO YES YES Q4 (APN-Profile) Q3(APN)
6 ENABLE YES NO YES NO Q3(APN) Q3(APN)
7 ENABLE YES NO NO YES Q4 (APN-Profile) Q1 (PGW-service)
8 ENABLE YES NO NO NO Q1 (PGW-service) Q1 (PGW-service)
9 ENABLE NO YES YES YES Q4 (APN-Profile) Q3(APN)
10 ENABLE NO YES YES NO Q2 (SGW-Service) Q3(APN)
11 ENABLE NO YES NO YES Q4 (APN-Profile) N/A (NO DSCP)
12 ENABLE NO YES NO NO Q2 (SGW-Service) N/A (NO DSCP)
13 ENABLE NO NO YES YES Q4 (APN-Profile) Q3(APN)
14 ENABLE NO NO YES NO Q3(APN) Q3(APN)
15 ENABLE NO NO NO YES Q4 (APN-Profile) N/A (NO DSCP)
16 ENABLE NO NO NO NO N/A (NO DSCP) N/A (NO DSCP)
17 DISABLE YES YES YES YES Q3(APN) Q3(APN)
18 DISABLE YES YES YES NO Q3(APN) Q3(APN)
19 DISABLE YES YES NO YES Q1 (PGW-service) Q1 (PGW-service)
20 DISABLE YES YES NO NO Q1 (PGW-service) Q1 (PGW-service)
21 DISABLE YES NO YES YES Q3(APN) Q3(APN)
22 DISABLE YES NO YES NO Q3(APN) Q3(APN)
23 DISABLE YES NO NO YES Q1 (PGW-service) Q1(PGW-service)
24 DISABLE YES NO NO NO Q1 (PGW-service) Q1 (PGW-service)
25 DISABLE NO YES YES YES Q3(APN) Q3(APN)
26 DISABLE NO YES YES NO Q3(APN) Q3(APN)
27 DISABLE NO YES NO YES N/A (NO DSCP) N/A (NO DSCP)
28 DISABLE NO YES NO NO N/A (NO DSCP) N/A (NO DSCP)
29 DISABLE NO NO YES YES Q3(APN) Q3(APN)
30 DISABLE NO NO YES NO Q3(APN) Q3(APN)
31 DISABLE NO NO NO YES N/A (NO DSCP) N/A (NO DSCP)
32 DISABLE NO NO NO NO N/A (NO DSCP) N/A (NO DSCP)