DSCP Marking

Feature Summary and Revision History

Summary Data

Applicable Product(s) or Functional Area

SMF

Applicable Platform(s)

SMI

Feature Default Setting

Disabled – Configuration Required

Related Changes in this Release

Not Applicable

Related Documentation

Not Applicable

Revision History

Revision Details

Release

Provided support for DSCP marking of control plane signaling messages

2021.01.0

First introduced.

Pre-2020.02.0

Feature Description

The SMF supports a mechanism for differentiated services code point (DSCP) marking of user plane data packets and control plane signaling messages.

The DSCP Marking feature enables the SMF to perform traffic classification and prioritisation to provide the appropriate quality of service (QoS) treatment. DSCP is the six most significant bit of the DiffServ field.

Implementation of this feature requires the use of certain CLIs commands to configure DSCP parameters for both signaling messages and data packets.

DSCP Marking for User Plane Packets

Feature Description

DSCP Marking supports granular configuration. For Interactive Traffic Class (ITC), the SMF supports per-APN configurable DSCP marking for Uplink and Downlink direction that is based on 5QI and ARP-Priority level. This support allows the users to assign different DSCP values for flows with the same 5QI but different ARP priority values. For example, the ability to assign DSCP values that are based on 5QI+ARP can be used to meet compliance on priority and emergency calling via VoLTE.

DSCP Marking is a CLI-controlled feature, which enables to create and map 5QI and ARP values to enforceable QoS parameters.

How the DSCP Marking Works for Data Packets

Allocation of different DSCP values for flows with the same 5QI, but different ARP values, works as follows:

  • Allows DSCP marking of packets that is based on 5QI+ARP combination.

  • 5QI+ARP configuration overrides any pre-entry of DSCP marking of packets that was based on 5QI+ARP combination.

  • 5QI-only DSCP entry overrides all existing 5QI+ARP configuration.

  • Allows implementation of associated DSCP marking for 5QI+ARP for Uplink and Downlink functionality.

Configuring 5QI-QoS Mapping

Use the following CLI commands to create and map 5QI values to enforceable QoS parameters.


configure 
   profile qos qos_name 
      dscp-map qi5 qi5_value [ arp-priority-level arp_value ] uplink user-datagram dscp-marking dscp_marking_value 
      dscp-map qi5 5qi_value [ arp-priority-level arp_value ] downlink { encaps-header { copy-inner | dscp-marking dscp_marking_value } | user-datagram dscp-marking dscp_marking_value encaps-header { copy-inner | dscp-marking dscp_marking_value } } 
      commit

NOTES:

  • dscp-map : Configures 5QI (referred as qi5 in the code) to DSCP-Marking mapping.

  • qi5 5qi_value : Identifier for the authorized QoS parameters. The 5qi_value must be within the range of 0 through 255.

  • arp-priority-level arp_value : Configures the ARP Priority Level. The arp_value must be an integer from 1 through 15.

  • downlink : Configures the downlink traffic.

  • uplink : Configures the uplink traffic.

  • user-datagram : Specifies the DSCP value to be applied to user datagram. Use this keyword to set the DSCP in the inner IP header in uplink or downlink direction.

  • dscp-marking : Specifies the DSCP value to be applied to packets with this 5QI. The value of dscp-marking must be a hexadecimal number from 0x00 through 0x3F.

  • encaps-header : Configures the DSCP value to be applied to encaps header. Use this keyword to set the DSCP in the outer-ip header in downlink direction.

  • copy-inner : Copies the DSCP value from inner IP header to the outer IP header.

The following is a sample configuration.


profile qos test 
 dscp-map qi5 1 downlink encaps-header copy-inner 
 dscp-map qi5 1 downlink encaps-header dscp-marking 0x3b 
 dscp-map qi5 2 downlink user-datagram dscp-marking 0x3b 
 dscp-map qi5 3 downlink user-datagram dscp-marking 0x3b encaps-header copy-inner 
 dscp-map qi5 4 downlink user-datagram dscp-marking 0x3b encaps-header dscp-marking 0x3f 
 dscp-map qi5 2 uplink user-datagram dscp-marking 0x3b 
 
 dscp-map qi5 1 arp-priority-level 1 downlink encaps-header copy-inner 
 dscp-map qi5 2 arp-priority-level 2 downlink encaps-header dscp-marking 0x3b 
 dscp-map qi5 4 arp-priority-level 3 downlink user-datagram dscp-marking 0x3b 
 dscp-map qi5 2 arp-priority-level 4 downlink user-datagram dscp-marking 0x3b encaps-header copy-inner 
 dscp-map qi5 4 arp-priority-level 5 downlink user-datagram dscp-marking 0x3b encaps-header dscp-marking 0x3f 
 dscp-map qi5 4 arp-priority-level 5 uplink user-datagram dscp-marking 0x3b

DSCP Marking for Control Plane Signaling

Feature Description

The SMF supports per-interface configurable DSCP marking for control plane signaling messages.


Note

The current implementation of DSCP marking supports only per RPC and Endpoint. Also, the customers should be aware of the DSCP code value range and its denoted priority.

How the DSCP Marking Works for Control Signaling

The SMF marks the ingress and egress packets after the QoS classification. The protocol endpoints provide the DSCP values at the time of registering the Endpoint and RPC host.

The SMF uses the dscp command in the endpoint and interface configuration to define the DSCP values.

The following table lists the commonly used DSCP values as described in RFC 2475.

Table 1. Commonly Used DSCP Values

DSCP Value

Decimal Value

Meaning

Drop Probability

Equivalent IP Precedence Value

101 110

46

High Priority Expedited Forwarding (EF)

N/A

101 - Critical

000 000

0

Best Effort

N/A

000 - Routine

001 010

10

AF11

Low

001 - Priority

001 100

12

AF12

Medium

001 - Priority

001 110

14

AF13

High

001 - Priority

010 010

18

AF21

Low

010 - Immediate

010 100

20

AF22

Medium

010 - Immediate

010 110

22

AF23

High

010 - Immediate

011 010

26

AF31

Low

011 - Flash

011 100

28

AF32

Medium

011 - Flash

011 110

30

AF33

High

011 - Flash

100 010

34

AF41

Low

100 - Flash Override

100 100

36

AF42

Medium

100 - Flash Override

100 110

38

AF43

High

100 - Flash Override

001 000

8

CS1

1

010 000

16

CS2

2

011 000

24

CS3

3

100 000

32

CS4

4

101 000

40

CS5

5

110 000

48

CS6

6

111 000

56

CS7

7

000 000

0

Default

101 110

46

EF

Limitations

The DSCP Marking is per interface basis and not per peer or session.

Configuring DSCP Marking for Control Plane Signaling

The following sections provide the configurations required for the DSCP marking of signaling messages.

Configuring DSCP Marking per Endpoint

Use the following sample configuration to configure the DSCP values at the endpoint level.


config 

      endpoint { gtp | li | protocol | radius | sbi } 
         dscp dscp_value 
         commit

NOTES:

  • The DSCP Marking configuration is applicable only to the following endpoints:

    • protocol

    • sbi

    • gtp

    • radius

    • li

  • dscp dscp_value : Specify the DSCP value for the control plane signaling messages. dscp_value must be a hexadecimal number from 0x00 through 0x3F or a decimal value ranging from 0 through 63.

  • The DSCP Marking feature supports dynamic change of the configuration.

Confuring DSCP Marking per Interface

Use the following sample configuration to configure the DSCP values at the interface level.


configure 

      endpoint { gtp | li | protocol | radius | sbi } 
         interface { coa-nas | gtpu | n4 | n7 | n10 | n11 | n16 | n40 | nrf | radius-client | s2b | s5 | s8 | upf-rcm-conn | upf-rcm-reg } 
            dscp dscp_value 
            commit

NOTES:

  • The DSCP marking configuration is applicable to all the interfaces defined within the configured endpoints.

  • dscp dscp_value : Configures the DSCP value for the control plane signaling messages. dscp_value must be a hexadecimal number from 0x00 through 0x3F or a decimal value ranging from 0 through 63.

  • The DSCP Marking feature supports dynamic change of the configuration.

  • The Service-based Interface (SBI) configuration applies to all the interfaces. If a specific interface configuration is present, it overrides the DSCP values.

  • For the interfaces to work properly, it is mandatory to configure vip-ip, vip-port, and loopbackPort at each interface level.