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 prioritization to provide the appropriate quality of service (QoS) treatment. DSCP is a significant bit in the DiffServ field.

This feature uses CLI commands to configure DSCP parameters for both signaling messages and data packets. For configuration details, see the Configuring 5QI-QoS Mapping and Configuring DSCP Marking for Control Plane Signaling sections in this chapter.


Note

This feature is also applicable on 4G calls with legacy interfaces.

DSCP Marking for Data 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.

The SMF sends the configured DSCP value to the UPF. Then, the UPF applies the DSCP marking on the uplink and downlink packets based on the 5QI and ARP.

How the DSCP Marking Works for Data Packets

This section describes how the DSCP marking can be performed for the 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 based on 5QI and ARP combination.

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

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

  • Allows implementation of associated DSCP marking for 5QI and ARP for uplink and downlink traffic.

Configuring 5QI-QoS Mapping

Use the following sample configuration to create and map 5QI values to enforceable QoS parameters.


config 
   profile qos qos_profile_name 
      dscp-map qi5 qos_id 
      arp-priority-level arp_value uplink user-datagram dscp-marking dscp_marking_value 
      arp-priority-level arp_value downlink { encsp-header { copy-inner | dscp-marking dscp_marking_value } | user-datagram dscp-marking dscp_marking_value } } 
      commit

NOTES:

  • dscp-map qi5 qos_id : Specify the ID for the authorized QoS parameters. qos_id must be an integer in the range of 1-255.


    Note

    If the DSCP configuration is unavailable at the QoS flow level but available at the QoS profile level, then DSCP configuration is used from the QoS profile level.

  • arp-priority-level arp_value uplink user-datagram dscp-marking dscp_marking_value : Configure the ARP priority level and then set the DSCP value in the inner IP header in uplink direction. This DSCP value is applied to the packets with the configured 5QI value.

    arp_value must be an integer in the range of 1-255.

    dscp_marking_value must be a hexadecimal number from 0x00 through 0x3F.

  • arp-priority-level arp_value downlink { encsp-header { copy-inner | dscp-marking dscp_marking_value } | user-datagram dscp-marking dscp_marking_value } } : Configure the ARP priority level and then set the DSCP value to be applied to encapsulation header or user datagram.

    If encsp-header is configured, set the DSCP in the outer-ip header in downlink direction or copy the DSCP value from inner IP header to the outer IP header.

    If user-datagram is configured, set the DSCP in the inner IP header in downlink direction.

    arp_value must be an integer in the range of 1-255.

    dscp_marking_value must be a hexadecimal number from 0x00 through 0x3F.

The following is an example 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

Verifying DSCP Configuration for UP Packets

This section describes how to verify the DSCP Marking feature configuration for the UP packets.

Use the show running-config profile qos command to verify the DSCP configuration for UP packets.

The following is an example output of the show running-config profile qos command. 

smf# show running-config profile qos 
profile qos abc
 ambr ul "250 Kbps"
 ambr dl "500 Kbps"
 qi5      7
 arp priority-level 14
 arp preempt-cap NOT_PREEMPT
 arp preempt-vuln PREEMPTABLE
 priority 120
 max data-burst 2000
exit
profile qos qos_1
 dscp-map qi5 1 arp-priority-level 5 uplink user-datagram dscp-marking 0x1e
 dscp-map qi5 1 arp-priority-level 5 downlink user-datagram dscp-marking 0x22 encsp-header copy-inner
 dscp-map qi5 2 arp-priority-level 6 uplink user-datagram dscp-marking 0x3e
 dscp-map qi5 2 arp-priority-level 6 downlink user-datagram dscp-marking 0x23 encsp-header copy-inner
 dscp-map qi5 3 arp-priority-level 12 uplink user-datagram dscp-marking 0x2f
 dscp-map qi5 3 arp-priority-level 12 downlink user-datagram dscp-marking 0x14 encsp-header copy-inner
 dscp-map qi5 6 downlink encsp-header copy-inner
 dscp-map qi5 7 downlink encsp-header dscp-marking 0x01
exit

DSCP Marking for Control Plane Signaling

Feature Description

The SMF supports marking of DSCP values to control packets as per the configuration at the interface.


Note

The current implementation of DSCP marking supports only per interface and protocol 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 interface.

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)

—

101 - Critical

000 000

0

Best Effort

—

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 feature has the following limitation:

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

Configuring DSCP Marking for Control Plane Signaling

This section describes how to configure the DSCP Marking feature for CP signaling messages.

Configuring the DSCP Marking feature involves the following steps:

Configuring DSCP Marking per Endpoint

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


config 
   instance instance-id gr_instance_id 
      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.

Configuring DSCP Marking per Interface

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


config 
   instance instance-id gr_instance_id 
      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.

Verifying DSCP Configuration for CP Signaling Messages

This section describes how to verify the DSCP Marking feature configuration for the CP signaling messages.

Use the show running-config instance instance-id gr_instance_id endpoint command to verify the DSCP configuration for control packets.

The following is an example output of the show running-config instance instance-id 1 endpoint command. 

smf# show running-config instance instance-id 1 endpoint
instance instance-id 1
 endpoint sbi
  replicas 2
  nodes 1
  dscp 24
  vip-ip 209.165.200.230
  interface nrf
   loopbackPort 9050
   vip-ip 209.165.200.236 vip-port 8090
   dscp 24
  exit
 exit
exit

OAM Support for DSCP Marking

Monitoring Support

The SMF uses the monitor protocol and monitor subscriber commands to view the configured DSCP value.