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HLR rejections vs DCR

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  • #51120 Reply
    Frood
    Guest

    One of our HLRs is overloaded and when it is in overload condition it rejects incoming requests. Usually HLR rejections should have an impact on SDCCH blocking/traffic/drops but what is interesting is that in siemens , I observe an increase in DCR cause radio link message failures whenever HLR rejections increase.

    Any comments?

    #51121 Reply
    Pix
    Guest

    Yes, that’s definitely strange. You mean you’re seeing channel release due to “radio lin messages” ? That’s on the A interface ?

    In other words : are you sure that you “DCR” is counting only TCH drops ?

    On the other hands, a non-response from the HLR might lead to a radio link failure.. If an internal MS timer expires, the Ms will end the connection, and the BTS will detect a radio link failure (MS not alive anymore) … but I’m really not sure.

    And finally : is there a Siemens feature that would trigger the authentication during the TCH, rather than the SDCCH ? If such a feature exists, that might explain your observation.

    #51122 Reply
    Bilal
    Guest

    Check if “Immediate Assignment on TCH” is enabled. In this case TCH drop rate can increase as a result of HLR fault. But still it should not be “radio failure”

    #51123 Reply
    Pix
    Guest

    oh yes, i forgot about this.. why alcatel doesn’t have the immediate assign on TCH ???

    it could be a radio failure, if my assumptions were correct in the previous post.

    #51124 Reply
    Frood
    Guest

    I dont like this, all my possible theories are being shot down.

    Good call on immediate TCH Assignment, but currently there is no cell on which this feature is activated in the whole network. 😀

    I noticed a rise in Handover Access failures aswell. Could it possibly be that during handover some kind of information is needed from different HLRs? Or maybe in party A a TCH is siezed but party B cannot respond due to timeout/congestion and the TCH on party A could be possibly cleared or dropped depending on timer values etc?

    #51125 Reply
    Bilal
    Guest

    TCH of Party A released due to B party’s congestion or no-reply is not considered as a TCH drop. It is a normal release event.

    #51126 Reply
    Frood
    Guest

    Bilal, yes it is a normal release event.Definitely right.I am compelled to agree.

    I am back to square one.

    #51127 Reply
    Pix
    Guest

    Have you checked the ciphering mode ? If there is a discrepancy between the ciphering mode of 2 cells, there might a problem…

    But basically, HLR is impacting the SDCCH drop, not the TCH drop.. you could look further into this path…?

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Reply To: HLR rejections vs DCR
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