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Original question:

DRA821U: Tx and Rx buffer allocation on switch

DRA821U: Queries regarding the prioritization at switch

Fhanindra Mantriraju
Intellectual 410 points
Part Number: DRA821U

Tool/software:

We have few questions regarding the Shaping of Traffic generated by NAD that is going to external network

Could you please confirm if our understanding is correct:

  • Could you please confirm if the above understanding is correct?
  • HQ queues configured on NAD recognizes the Traffic generated by NAD based on the PCP field set by NAD in the VLAN tag?
  • Does the TI driver automatically map HW quesues with PCP values or is there any specific configuration needed to acive this ( I mean, is it still possible to map PCP2 to a high priority queue)
  • Can the Traffic generated by NAD leaving BAM be routed to BAM kernel space or handled directly by switch ? This is needed because we need to conclude on the specific configuration needed to handle the Traffic handling on switch side 
  • 0
    TI__Mastermind 30430 points

    Hi,

    Fhanindra Mantriraju said:
    Could you please confirm if the above understanding is correct?

    The only thing I would modify here is that the tc rate-limiting here is built into the egress queues and does not exist as a separate block in the hardware.

    Fhanindra Mantriraju said:
    HQ queues configured on NAD recognizes the Traffic generated by NAD based on the PCP field set by NAD in the VLAN tag?

    The ingress queue on socnet1 (there is only 1 Rx queue) will assign a switch priority to the packet based on the PCP value of VLAN tag. By default it is 1-1 mapped. While egressing, the switch priority will be used as egress priority. So in your case, the priority will be maintained for the packet going through the switch.

    Fhanindra Mantriraju said:
    Does the TI driver automatically map HW quesues with PCP values or is there any specific configuration needed to acive this ( I mean, is it still possible to map PCP2 to a high priority queue)

    It is possible, but it will require a patch. It is not configurable at runtime.

    Fhanindra Mantriraju said:
    Can the Traffic generated by NAD leaving BAM be routed to BAM kernel space or handled directly by switch ? This is needed because we need to conclude on the specific configuration needed to handle the Traffic handling on switch side 

    I didn't get what you are trying to do here. Can you explain a bit more here.

    Regards,
    Tanmay

  • 0 in reply to Tanmay Patil
    Intellectual 410 points
    Tanmay Patil said:
    Can the Traffic generated by NAD leaving BAM be routed to BAM kernel space or handled directly by switch ? This is needed because we need to conclude on the specific configuration needed to handle the Traffic handling on switch side 

    I didn't get what you are trying to do here. Can you explain a bit more here.

    Hi Tanmay,

    What i meant was If there is a EGGRESS TRAFFIC on BAM coming directly from NAD 

    For example. VLAN77 internet traffic :  WAN--> IPA/ Modem -->Eth0 (NAD) --> Port2( socnet1) --> port3 (socnet0) --> BAM

    Would the HTB qdesc applied on BMA kernel be applicable for such traffic? or they are directly prioritized by Tx queues based on PCP?

  • 0 in reply to Tanmay Patil
    Intellectual 410 points

    Hi Tanmay,

    As discussed over the call today,

    • It is confirmed that by default Tx queue size is 8 on external ports and no need to increase
    • On host port, we have an option to increase Tx queue size from 1 to 8 ( patch is available)
    • By default PCP is mapped 1:1 to Tx queue --> meaning highest PCP goes to highest queue 
    • However, this can be configured on host port to make sure certain PCP is given the highest priority
    • On external ports, a patch is needed to map PCPs to queues based on required priority

    The following is the expectation 

    • Confirm the feasibility of providing patch with above priorities.
    • Please let us know how to configure the PCP with priorities on host port 
    • Is it possible to give untagged packets highest prio? what is the default priority for untagged packets 
  • 0 in reply to Fhanindra Mantriraju
    Intellectual 410 points

    Hi Tanmay,

    After further discussion with BMW, the following priorities 

    Could you please provide a patch for the same:

    Priority PCP ( >=3) Applicable port Traffic type
    untagged All PTP/ EAPOL
    7 4 All Frame preemption
    6 3 All AVnu class A traffic, noise cancelling, warnings
    5 2 All Telephony, AbVnu class C, computer vision
    4 5 All future use
    3 7 All some/ip, npdu
    2 6 All future use 
    1 0 All Best effort (web, streaming, internet etc..)
    0 (Lowest) 1 All Lower effort , DLT, Debugging

    Also, as discussed kindly update us with the handling of untagged packets