Support packet trimming

[sallylsy]

Change Scope

• Add parameters to support packet trimming.
• This change is backwards compatible.

Platform Implementations

• Implementation A: Sonic HLD.
• Implementation B: Nvidia Supports.

Tree View

 module: openconfig-qos
   +--rw qos
      +--rw classifiers
      |  +--rw classifier* [name]
      |     +--rw name      -> ../config/name
      |     +--rw config
      |     |  +--rw name?   string
      |     |  +--rw type?   enumeration
      |     +--ro state
      |     |  +--ro name?   string
      |     |  +--ro type?   enumeration
      |     +--rw terms
      |        +--rw term* [id]
      |           +--rw id            -> ../config/id
      |           +--rw config
      |           |  +--rw id?   string
      |           +--ro state
      |           |  +--ro id?   string
      |           +--rw conditions
      |           |  +--rw l2
      |           |  |  +--rw config
      |           |  |  |  +--rw source-mac?             oc-yang:mac-address
      |           |  |  |  +--rw source-mac-mask?        oc-yang:mac-address
      |           |  |  |  +--rw destination-mac?        oc-yang:mac-address
      |           |  |  |  +--rw destination-mac-mask?   oc-yang:mac-address
      |           |  |  |  +--rw ethertype?              oc-pkt-match-types:ethertype-type
      |           |  |  +--ro state
      |           |  |     +--ro source-mac?             oc-yang:mac-address
      |           |  |     +--ro source-mac-mask?        oc-yang:mac-address
      |           |  |     +--ro destination-mac?        oc-yang:mac-address
      |           |  |     +--ro destination-mac-mask?   oc-yang:mac-address
      |           |  |     +--ro ethertype?              oc-pkt-match-types:ethertype-type
+     |           |  +--rw fabric
+     |           |     +--rw config
+     |           |     |  +--rw fabric-priority?   uint8
+     |           |     +--ro state
+     |           |        +--ro fabric-priority?   uint8
      |           +--rw actions
      |              +--rw config
      |              |  +--rw target-group?   -> ../../../../../../../forwarding-groups/forwarding-group/config/name
      |              +--ro state
      |              |  +--ro target-group?   -> ../../../../../../../forwarding-groups/forwarding-group/config/name
      |              +--rw remark
      |                 +--rw config
      |                 |  +--rw set-dscp?      uint8
      |                 |  +--rw set-dot1p?     uint8
      |                 |  +--rw set-mpls-tc?   uint8
      |                 +--ro state
      |                    +--ro set-dscp?      uint8
      |                    +--ro set-dot1p?     uint8
      |                    +--ro set-mpls-tc?   uint8
      +--rw buffer-allocation-profiles
      |  +--rw buffer-allocation-profile* [name]
      |     +--rw name      -> ../config/name
      |     +--rw config
      |     |  +--rw name?   string
      |     +--ro state
      |     |  +--ro name?   string
      |     +--rw queues
      |        +--rw queue* [name]
      |           +--rw name      -> ../config/name
      |           +--rw config
      |           |  +--rw name?                                  -> ../../../../../../queues/queue/config/name
      |           |  +--rw dedicated-buffer?                      uint64
      |           |  +--rw dedicated-buffer-temporal?             uint64
      |           |  +--rw use-shared-buffer?                     boolean
      |           |  +--rw shared-buffer-limit-type?              identityref
      |           |  +--rw static-shared-buffer-limit?            uint32
      |           |  +--rw static-shared-buffer-limit-temporal?   uint32
      |           |  +--rw dynamic-limit-scaling-factor?          int32
+     |           |  +--rw packet-discard-action?                 enumeration
      |           +--ro state
      |              +--ro name?                                  -> ../../../../../../queues/queue/config/name
      |              +--ro dedicated-buffer?                      uint64
      |              +--ro dedicated-buffer-temporal?             uint64
      |              +--ro use-shared-buffer?                     boolean
      |              +--ro shared-buffer-limit-type?              identityref
      |              +--ro static-shared-buffer-limit?            uint32
      |              +--ro static-shared-buffer-limit-temporal?   uint32
      |              +--ro dynamic-limit-scaling-factor?          int32
+     |              +--ro packet-discard-action?                 enumeration
+     +--rw packet-trim
+        |  +--rw symmetric-dscp?   uint8
+        |  +--rw traffic-class?    uint8
+        +--rw state
+           +--rw symmetric-dscp?   uint8
+           +--rw traffic-class?    uint8

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the QoS YANG model by introducing comprehensive support for packet trimming and fabric priority configuration. The primary goal is to provide network operators with more flexible and nuanced control over packet handling, particularly in congestion scenarios, by allowing packets to be trimmed rather than fully dropped. This also includes the ability to define internal fabric priorities for traffic management.

Highlights

• Packet Trimming Support: Added new YANG parameters to support packet trimming functionality, allowing network devices to truncate packet payloads while preserving headers for diagnostic purposes instead of a full drop.
• Fabric Priority Configuration: Introduced new configuration options for defining fabric priority within QoS classifier terms, enabling more granular control over internal switching fabric traffic.
• Backwards Compatibility: The changes are designed to be backwards compatible, ensuring existing configurations and systems will continue to function without disruption.

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[gemini-code-assist]

Code Review

This pull request introduces new YANG models for configuring fabric parameters, packet discard actions (DROP/TRIM), and switch-level packet trimming. Specifically, it adds fabric-params-top and fabric-params-config to define fabric priority, integrates these into QoS match fields, and introduces packet-discard-action in QoS memory management. Additionally, qos-packet-trim-top and packet-trim-config are added to define symmetric DSCP and traffic class for trimmed packets, which are then integrated into the main QoS model. The review comments point out minor typos in the descriptions for fabric parameters and suggest clarifying the definition of 'symmetric packet' for better understanding.

[dplore]

/gcbrun

[OpenConfigBot]

No major YANG version changes in commit 9e05571

[dplore]

Will review in March 31, 2026 OC Operator meeting