DP83867ERGZ-S-EVM: Back to Back SGMII Link Register settings

Hi Franz,

I will try to replicate this setup on my end and update you. Please give me time till end of the week to get back to you.

Thanks,
Rahul

Thanks Rahul,

don't hesitate to ask if you need more information.

Franz

Will do!

Regards,

Rahul

Hi Franz,

I have tried setting up two EVM back to back SGMII in their default configurations, used Smart bits to send packets for some time. I haven't noticed any link drop or RX errors.

Can you please share images of your test setup and the SMA cable lengths used to connect between the boards?

Thanks,
Rahul

Hi Rahul,

please apologize my late answer, was on vacation for a few days :).

Here's a image of my setup, SMA cable length is approximately 20cm.

The raspberry pi is for reading MDIO registers. When using iperf3 on notebooks I do not see the RX_ER, but when using the Etherscope I do.

With this setup I see sporadic TCP and UDP errors using Iperf3.

I know this is hard to reproduce, but could you please clarify what your colleague Hillman Lin meant in this thread?

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1111527/dp83867ergz-s-evm-about-repeater-operation-by-back-tp-back-connection-of-two-dp8367e-sgmii-evms

Hi Franz,

We do not have Etherscope to replicate the same setup. I have used smartbits for packet generation and this didn't cause any RX_ERs to be triggered.

Another test setup I can think of is using Iperf on a PC, but you have mentioned no issues with this setup as well.

Franz Forstmayr1 said:

I know this is hard to reproduce, but could you please clarify what your colleague Hillman Lin meant in this thread?

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1111527/dp83867ergz-s-evm-about-repeater-operation-by-back-tp-back-connection-of-two-dp8367e-sgmii-evms

When using as a repeater, if you want to avoid the SGMII ANEG process you can force the speeds on both the PHYs.

Thanks,
Rahul

Hi Rahul,

Franz Forstmayr1 said:

The two boards can establish a connection but when running an iperf3 measurement or a netAlly LANBERT measurement I can see packet errors of about 0.01%.

I can establish a connection but see udp packet loss with iperf3 too. However I'm not sure how valid the iperf3 measurement is in this case.

Hi Franz,

Can you please share register dump on both the EVMs used in the test setup after running the test and noticing packet loss ?

Can you also share the iperf3 logs as well ?

Did you try changing the SMA cables and notice different results ? I would also recommend in using different link partners also.

Thanks,
Rahul

Hi Rahul,

I think I found the issue, at least the measurement with the Netally Etherscopes. When I change the "PORT TYPE" in Register CFG1 to 1 - Multiport Device, the test runs without any error. In another document I saw this is a recommended setting for Switches and Repeaters, and my application is basically a repeater. Another option is to force 1000Base-T Master mode at the device next to the generator.

However I would like to avoid the use of an microcontroller, and unfurtonately there's no strapping option to set the "PORT TYPE". Could you recommend another Phy with "PORT TYPE" strapping option to use in this application? 

Hi Franz,

Can you please share the document that refers to the PORT TYPE to be configured to Multi Port ?

Thanks,
Rahul

Hi Rahul,

I found this option in the Datasheet of DP83867 section 8.4.3.2, I set the regiser according to table 8.6.10.

Best Regards
Franz

Hi Franz,

Is this the section you are referring to ?

Regards,
Rahul

yes exactly!

I couldn't find any note that refers to change PORT TYPE to multi port selection in that section. Just wanted to confirm where we have provided that guidance.

Regards,
Rahul