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DL LLC Congestion in ALU-2G

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  • 22nd February 2016 at 06:11 #69877
    Hamza
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    Any GPRS/EGPRS Expert Please support,

    we are facing high ‘DL LLC Congestion’ in our 2G Network which is severely hitting THPT

    There is no any congestion in radio access side( radio/ater/abis/GPU etc)

    so , how to cope such kind of congestion which is suspected on other interface ( GB/GIU) but impacting radio KPIs?
    Do we have choice to tune some paramter from radio side to cope such congestions?

    23rd February 2016 at 21:29 #69878
    Pix
    Guest

    Hi Hamza,

    That’s an interesting issue. The SGSN is sending LLC frames to your MS’s, but the MFS is sending control frames indicating that the downlink throughput is too high at Gb level and will saturate the BSS.

    The issue is indeed in the BSS, and not in the NSS side. The BSS is telling the NSS to stop sending data because it can’t handle it.

    Now your job is too find why & where is the BSS “limited”.

    Check out the counters that measures the PMU load in the MFS, and look at hourly values :
    GPRS_PMU_CPU_power_budget
    – if > 95% the PMU enters in overload state (GPRS_PMU_OVERLOAD_TIME)

    Look at the number of MS Contexts :
    GPRS_MS_IDLE_MAX / 4000 = a load (%)
    – if 100% then PMU is overloaded

    Look at the number of TBF ESTABLISHED :
    GPRS_DL_ESTAB_MAX + GPRS_UL_TBF_MAX)*0.7 < 3840 - if not verified then PMU is overloaded One of these 3 possibilities should be the cause of your touble (CPU load, MS Contexts, TBF numbers) Leet me know, and then we can try to fix it... Cheers Pix

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