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TLK10034: HS Errors on optical port when low traffic

Samuel Bobrowicz
Prodigy 80 points
Part Number: TLK10034

We are using the TLK10034 on a PCB with two of the HS ports attached to 10G Optical SFP modules. Base KR mode with The LS side of these ports are attached to a Marvell 88E6390X 11-port switch in XAUI mode. The HS ports are in BASE KR mode with link-training and auto negotiation disabled. We are using register bring-up sequence and values for the TLK's registers that were suggested here: https://e2e.ti.com/support/interface/f/138/p/576559/2124111#2124111. 

  • 0
    Prodigy 80 points

    Oops, it looks like most of my post was lost. I was able to recover it by using the browser back button :)  Reposting below:

    We are using the TLK10034 on a PCB with two of the HS ports attached to 10G Optical SFP modules. Base KR mode with The LS side of these ports are attached to a Marvell 88E6390X 11-port switch in XAUI mode. The HS ports are in BASE KR mode with link-training and auto negotiation disabled. We are using register bring-up sequence and values for the TLK's registers that were suggested here: e2e.ti.com/.../2124111

    For the most part our link is operating fine, however we have a higher rate of intermittent packet loss than we would hope, and are exploring multiple avenues to address it. One thing that I noticed while debugging this issue is that the TLK will report constant HS errors when there is low traffic incoming on the optical cable. When I begin transmitting large amounts of video traffic to the TLK, these HS errors stop occurring. No other errors are reported at the TLK during low traffic. This is highly repeatable on all of our TLK HS ports which are connected to SFP optical cables, across multiple units. I've tried all documented HS tuning registers, yet the quirk persists. The other TLK HS ports on our board are connected directly to a BASE-KR receiver on the same PCB, and we do not see this same behavior.

    Is this expected behavior when using the TLK10034 with an Optical SFP module? Anybody got a guess what might cause it if not? I can provide more info if needed.

  • 0 in reply to Samuel Bobrowicz
    Prodigy 80 points

    I just noticed that occasionally the RX_FIFO_UNDERFLOW bit is set when the HS errors are presenting. I'm not sure if this a clue or just caused by the HS errors.

  • 0 in reply to Samuel Bobrowicz
    TI__Mastermind 19235 points

    Hi,

    Related to: "One thing that I noticed while debugging this issue is that the TLK will report constant HS errors when there is low traffic incoming on the optical cable"

    • What do you mean by low traffic? Is valid 10G Ethernet encoded date being transmitted when the traffic is not enabled. Please clarify data encoding and min/max transition density for case of traffic enabled vs not enabled

    Cordially,

    Rodrigo Natal

    HSSC Applications Engineer