Switch ID question for VOQ systems

[tbgowda]

Hello,

This is probably a SAI question but I am asking it here since I am seeing a behavior in syncd that is leaving me baffled.

The switch ID terminology is confusing me, I am hoping to get these questions answered and get a clarification.

Consider an example VOQ switch with two linecards : LC0 and LC1

Lets start from create_switch SAI API. The output parameter switch_id is the object ID of the "switch" formed by the SAI layer and returned back to the caller. Lets call it "switch_object_id" to avoid confusion.

/**
 * @brief Create switch
 *
 * SDK initialization/connect to SDK. After the call the capability attributes should be
 * ready for retrieval via sai_get_switch_attribute(). Same Switch Object id should be
 * given for create/connect for each NPU.
 *
 * @param[out] switch_id The Switch Object ID
 * @param[in] attr_count Number of attributes
 * @param[in] attr_list Array of attributes
 *
 * @return #SAI_STATUS_SUCCESS on success, failure status code on error
 */
typedef sai_status_t (*sai_create_switch_fn)(
        _Out_ sai_object_id_t *switch_id,
        _In_ uint32_t attr_count,
        _In_ const sai_attribute_t *attr_list);

Now, in a VOQ system should the SAI layer return the same "switch_object_id" for all the nodes in the chassis? In our VOQ switch, should SAI on LC0 and LC1 return the same switch_object_id or different "switch_object_id"s?

There is a "switch_id" in the DEVICE_METADATA of the SONiC config_db.json. Lets call it "switch_voq_id". Ex:

    "DEVICE_METADATA": {
        "localhost": {
            "hwsku": "Force10-S6000",
            "platform": "x86_64-kvm_x86_64-r0",
            "mac": "52:54:00:75:65:02",
            "switch_id": "2",
            "switch_type": "voq",
            "max_cores": "48",
            "type": "Spine",
            "asic_name": "Asic0",
            "hostname": "Linecard0",
            "deployment_id": "1"
        }
    }

This I presume is local to the node, meaning in our example LC0 and LC1 will have different "switch_voq_id"s. If not, please correct me.

This "switch_voq_id" is also what is used in defining system port configs in SONiC?

    "Linecard2|Asic0|Ethernet112": {
      "speed": "40000",
      "system_port_id": "61",
      "switch_id": "2",
      "core_index": "1",
      "core_port_index": "13"
    }

Questions:

1. Is there any co-relation between switch_voq_id and switch_object_id?
2. If yes, when create_switch is called, should the SAI layer embed the switch_voq_id into the switch_object_id?
3. Say, SAI generates a switch_object_id following some internal logic, will all the subsequent invocation of SAI APIs from syncd use this generated switch_object_id for all the SAI objects (once that needs switch_object_id)?