topic ls1028 TSN 802.1QBV queueMaxSDU and guard band question in Layerscape

ls1028 TSN 802.1QBV queueMaxSDU and guard band question

xinliwang — Wed, 09 Aug 2023 02:44:49 GMT

Hi @yipingwang and community

I wanna discuss with you guys regarding the definition of queueMaxSDU and guard band in NXP 802.1BV.

According to the reference menu the guardband is set by"--maxSDU"

and the maxSDU definition is "queueMaxSDU" which also set by "--maxSDU"

But according to the IEEE802.1qbv. The queueMaxSDU and guardband has no absolut connection. We can determine the size we need for the guard bands, depending on the queueMaxSDU which means we can set queueMaxSDU and guardband independently. On the other hand, these two parameters no need to be equal.

But on NXP board ls1028ardb, we can not set both parameters independently. I wonder is this a unique NXP qbv feature or it could be imprved based on IEEE802.1QBV standard?

Thanks.

Re: ls1028 TSN 802.1QBV queueMaxSDU and guard band question

yipingwang — Mon, 14 Aug 2023 06:53:15 GMT

Currently in linux driver, guard band is calculated according to "QSYS_QMAXSDU_CFG_x", it's MAX SDU for traffic class x(0~7).
Customer can also set "PORT_MAX_SDU", this value is used for guard band calculation for a traffic class if the QMAXSDU_CFG_* is set to '0'.

for LS1028 switch IP, guard band is calculated according to the MAX SDU of the related traffic class or port.

Thanks

Re: ls1028 TSN 802.1QBV queueMaxSDU and guard band question

xinliwang — Mon, 14 Aug 2023 10:14:22 GMT

Hi @yipingwang

Thank you for your reply;

It seems like we could not set guardband independently.

But I wonder does eno0 port has guardband too? I could not find any description on ENETC chapter.

Thank you