Either your network is f*cked up or you use techniques like Spanning Tree to explicitely prevent your signal to be ever routed back to you.Īs you can see, the internal data routing is essential. broadcast packages) lead to serious trouble in the network.Ĭase #3: You have a complicated network setup where loops are possible. It does not make sense to do it and would in some cases (e.g. The switch will in its routing automatically never send the signal back to the source. The NIC has no interest in reading its own signal while sending it.Ĭase #2: The NIC sends the data to a switch. Nobody will talk back to the NIC about the signal. A cost-effective, compact Ethernet loopback tool that can be used as a remote unit to return test traffic, enabling service providers to turn-up and install. configure the internal PHYs on the Ethernet switch with specific MAC. So the loopback high level packet path is as follow: CPU->PHY0 (chip)->Ethernet switch (chip)'s internal PHY->PHY0 (chip)->CPU. Configure the PHY to be in reverse loopback mode by setting MDIO registers. It connects the TX+/- to RX+/- pins for each internal PHY's on the Ethernet switch chip. However I doubt you will ever be able to test the PHY without a second receiver.Ĭase #1: The NIC sends the data to a hub (do these still exist?). Ethernet Physical Layer Compliance (IEEE 802.3) testing as the device under.
Note if the Marvell PHY is supposed to support this, then it may be good to contact them as to why it's not working? Have you probed the SGMII RX signalling (DSP perspective RX or the TX from Marvell PHY perspective) to see if there's any corresponding activity immediate after DSP SGMII TX signalling is transmitted.As you may have guessed, this is not a bug but a feature (and an essential one). A technician or system gains access to the ETE and connects it in some fashion to the network (via manual connection for an Ethernet Test Equipment-Instrument. You'd need to configure the SerDes SGMII to Loopback mode and the SGMII Receive and Transmit SerDes to Loopback mode.
Yes, there's example code but if you're building your code you should be able to do it by setting the SGMII to loopback mode. This is at the analog side and is not a digital loopback of the MAC. The DSP's SGMII PHY has loopback mode support built in. That said, you don't need to do this to perform a PHY loopback on the DSP. Marvell may support something beyond this. Low cost Ethernet loopback device for testing end-to-end network performance when paired with MX100+, MX120+, MX300, TX300, or 3rd party Ethernet testers Ideal. Usually these capabilities again are Tx to Rx loopback of the device itself. I'm not sure of the Marvel PHY's loopback capabilities, as you're aware if you have their data sheet it's under NDA and I don't have a copy of it personally so I can't look at what specifically it says. That's why I was very specific in saying that the DSP cannot do a loopback an Rx to Tx. Also, I thought you were referring to the DSP's PHY being in loopback mode.
That you had the PC Pinging the board and expected a loopback. It sounded to me on the last one when you said you were pinging the board. (to figure out where the problem is i tried to sgmii loopback mode, gbe switch loopback mode and the pkdma loopback mode, but only the last one works. So thats my problem, i cant figure out where the package is loopbacked to and what to problem is or what i do wrong. i see a package coming into the rx queue.īut now i want to loopback the phy so that the package i send to the phy comes back into my rx queue. but when i setup the loopback mode in the phy (by doing mdio accesses) and send a package i dont see it coming back into my recieving queue. after that i pinged to board to see if the recieving function would pop a package from the rx queue.
at first i tried to send a package (custom array with some values) by popping the queue then pushing it with wireshark i saw the package coming in. I used the code from the bootloader, were it gets the firmware by nfs, to get the queue manager system running. If the link lights on the other side of the equipment turns on, then your cable isn’t faulty. Simply plug one end of the cable to the adapter and the other end to a switch or router. By Clicking on the View and Apply button of the Loopback function, this provides the ability to apply soft loopbacks on the Colt Network Interface Devices. i am building a test were i want to test the Phy ethernet controller by doing a loopback test. You can also use the loopback plug to test the Ethernet cable. I am working on the same level as the bootloader.