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CC3120MOD: Station mode is unstable means ping response time varies too much

Mahendra Rana
Expert 1010 points
Part Number: CC3120MOD
Other Parts Discussed in Thread: CC3220SF

Can anyone help me that why in station mode ping behave strange. While no traffic is occurring I get ping times around 50-200 ms (sometimes once or two below 10ms as well).

But once I started ModbusTCP traffic by query through modbus tcp/ip client then ping time goes down to well below 10ms (generally about 2ms).

Is it this could be some low power mode where WiFi module go down to sleep, when there is no traffic (hence increased ping time). When traffic is occurring there is no time to go down to sleep and therefore ping times goes down to single digit ms.

But In Access Point mode ping is about 1-2 ms all the time.

Reply from 192.168.1.22: bytes=32 time=42ms TTL=128

Reply from 192.168.1.22: bytes=32 time=65ms TTL=128

Reply from 192.168.1.22: bytes=32 time=89ms TTL=128

Reply from 192.168.1.22: bytes=32 time=109ms TTL=128

Reply from 192.168.1.22: bytes=32 time=2ms TTL=128    <-- Start query through modbus tcp/ip client

Reply from 192.168.1.22: bytes=32 time=2ms TTL=128

Reply from 192.168.1.22: bytes=32 time=2ms TTL=128

Reply from 192.168.1.22: bytes=32 time=1ms TTL=128

Reply from 192.168.1.22: bytes=32 time=2ms TTL=128

Reply from 192.168.1.22: bytes=32 time=2ms TTL=128

Reply from 192.168.1.22: bytes=32 time=1ms TTL=128

Reply from 192.168.1.22: bytes=32 time=2ms TTL=128

Reply from 192.168.1.22: bytes=32 time=2ms TTL=128

Reply from 192.168.1.22: bytes=32 time=8ms TTL=128

Reply from 192.168.1.22: bytes=32 time=150ms TTL=128  <-- Stop query through modbus tcp/ip client

Reply from 192.168.1.22: bytes=32 time=72ms TTL=128

Reply from 192.168.1.22: bytes=32 time=299ms TTL=128

Reply from 192.168.1.22: bytes=32 time=113ms TTL=128

Reply from 192.168.1.22: bytes=32 time=2ms TTL=128

Reply from 192.168.1.22: bytes=32 time=161ms TTL=128

Reply from 192.168.1.22: bytes=32 time=186ms TTL=128

Reply from 192.168.1.22: bytes=32 time=205ms TTL=128

 

Can anyone help me, how to resolve this?

 

Regards,

Mahendra Rana

  • 0
    Guru 77965 points

    Hi,

    Your assumptions are correct. If you need to achieve best performance (lower latency) in STA mode, you need to set "always on" power policy. But this settings increase power consumption.

    ret = sl_WlanPolicySet(SL_WLAN_POLICY_PM, SL_WLAN_ALWAYS_ON_POLICY, NULL, 0);

    Jan

  • 0 in reply to Jan D
    Expert 1010 points

    OK. I have tried to set in always power ON mode the ping response improved, but still some time it took more reply time why?

    Reply from 192.168.43.237: bytes=32 time=5ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=49ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=5ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=109ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=3ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=4ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=6ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=16ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=3ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=3ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=3ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=3ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=3ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=3ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=13ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=6ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=7ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=109ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=6ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=7ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=7ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=6ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=9ms TTL=128
    Reply from 192.168.43.237: bytes=32 time=7ms TTL=128

  • 0 in reply to Mahendra Rana
    Guru 77965 points

    Hi,

    I am not sure. Maybe this is related to your network infrastructure (used access point) somehow. Maybe you can use wireless sniffer to determine what is going on at WLAN.

    btw... what SDK version do you use and ServicePack version do you have uploaded inside device?

    Jan

  • 0 in reply to Jan D
    Expert 1010 points

    OK, I will debug it through sniffer. And get back to you if having some issue.

    SDK and service pack of my module are: -

    ==============================================

    CHIP: 0x31000000
    MAC: 2.0.0.0
    PHY: 2.2.0.6
    NWP: 3.9.0.6
    ROM: 0
    HOST: 3.0.1.41

    =======================================

  • 0 in reply to Jan D
    Expert 1010 points

    Please just check and update me that my used sdk and service pack version not having this bug and later it was resolved?

    Regards,

    Mahendra Rana

  • 0 in reply to Mahendra Rana
    Guru 39650 points

    Hi,

    It looks that your service pack is slightly old (from Sep 2018). From this reason I recommand you update. Latest SerivcePack you find inside CC3220 SDK and SimpleLink driver as well. I am not able easily check if this exact issue was fixed at some particular ServicePack.

    With my CC3220SF and latest service pack I see similar behaviour. I am pretty sure, that it is caused by RF interferences in my case.

    Pinging 192.168.1.44 with 32 bytes of data:
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128
Reply from 192.168.1.44: bytes=32 time=2ms TTL=128
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128
Reply from 192.168.1.44: bytes=32 time=3ms TTL=128
Reply from 192.168.1.44: bytes=32 time=51ms TTL=128
Reply from 192.168.1.44: bytes=32 time=2ms TTL=128
Reply from 192.168.1.44: bytes=32 time=2ms TTL=128
Reply from 192.168.1.44: bytes=32 time=2ms TTL=128
Reply from 192.168.1.44: bytes=32 time=3ms TTL=128
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128
Reply from 192.168.1.44: bytes=32 time=14ms TTL=128
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128
Reply from 192.168.1.44: bytes=32 time=3ms TTL=128
Reply from 192.168.1.44: bytes=32 time=6ms TTL=128
Reply from 192.168.1.44: bytes=32 time=2ms TTL=128
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128
Reply from 192.168.1.44: bytes=32 time=4ms TTL=128
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128
Reply from 192.168.1.44: bytes=32 time=3ms TTL=128
Reply from 192.168.1.44: bytes=32 time=2ms TTL=128
Reply from 192.168.1.44: bytes=32 time=4ms TTL=128
Reply from 192.168.1.44: bytes=32 time=6ms TTL=128
Reply from 192.168.1.44: bytes=32 time=2ms TTL=128
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128
Reply from 192.168.1.44: bytes=32 time=2ms TTL=128
Reply from 192.168.1.44: bytes=32 time=1ms TTL=128

    Jan

  • 0 in reply to Mahendra Rana
    TI__Mastermind 22935 points

    Hi Mahendra,

    Our latest service packs would always have the latest bug fixes and features which you can take from the latest CC32XX SDK. 

    Jesu