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TIMERS – Implicit IMSI Detach, VLR purge

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  • #57185 Reply
    Viki
    Guest

    Hello colleagues.
    We have a few problems in the netork while changing Implicit IMSI Detach timer, VLR purge timer.
    What are the value of these timers in your networks? Are there any recomendations, standarts, tips?

    Thank you in advance

    #57186 Reply
    Viki
    Guest

    Hey, really nobody has any information? ๐Ÿ™

    #57187 Reply
    Pix
    Guest

    The only thing I know is that the implicit detach timer should be greater than the T3212 (BSS LU timer), more than twice the value, to be on the safe side… (to be confirmed / discussed by NSS Gurus)

    Implicit IMSI Detach timer > 2 x T3212

    Cheers,
    Pix

    #57188 Reply
    Viki
    Guest

    Thank you Pix!

    NSS Gurus, any idea, please?

    #57189 Reply
    Pan
    Guest

    Dear, Viki!
    VLR purging is triggered rather by some events than timer expiration. It is vendor specific event. For example, VLR was filled on 80%. After that, VLR may purges all subscribers which were inactive more than 5 days.

    #57190 Reply
    Pix
    Guest

    What about the Implicit Detach timer in VLR ?

    #57191 Reply
    Pan
    Guest

    Hello, Pix! Glad to meet you again:} You already said that a value of Implicit Detach timer is derived from periodic location update timer (must be greater, but it is not mandatorily be greater more than 2 times). I have no more to say.

    #57192 Reply
    Pix
    Guest

    Hi Pan,

    So we meet again… (western music…) :ยฐ

    Actually, you gave an example that VLR would detach subscribers after 5 days… but the Implicit detach timer is certainly less than one day, isn’t it? At the expiry of this timer, isn’t the subscriber cleared from the VLR ?

    (I might sound a bit ignorant about VLR… that’s probably because I am !!)

    #57193 Reply
    Pan
    Guest

    Hello, Pix!
    VLR purging and Implicit Detach are independent procedures in a VLR. They are used to avoid unwanted signalling load on network (paging and signalling between HLR and VLR) when subscriber is unreachable a long time. In our network Implicit Detach Timer may be changed from 6 min. to 30 hours. When Implicit Detach timer expires than subscriber is detached but isn’t cleared from VLR. When VLR purges subscriber, then it deletes his entry and sends Purge message to HLR.

    #57194 Reply
    Pix
    Guest

    Pan, ok, that’s clear now. thanks ๐Ÿ™‚

    #57195 Reply
    Viki
    Guest

    Hello Pan!
    Thank you for the information.
    You said you configure the Implicit Detach Timer in your network with different value varying from 6 min to 30 hours. What could be a reason to have the defferent values over the network?
    I believe it is better to have it the same on the all elements, isn’t it?
    By the way, what value of the Purge timer you have? What will happen with a MS wich was Detached or Purged when this MS became available?

    #57196 Reply
    Pan
    Guest

    Hi Viki!
    I didn’t say that we have different Implicit Detach Timer values ๐Ÿ™‚ I said that the range from 6 min to 30 hours is allowed in our equipment.
    About VLR purge – see my post from 9 Jun 2009. It is fixed value in our equipment.
    When MS becames available it performs ordinary idle mode procedures (celection/reselection, periodic location updating). When the first contact with network takes place then MS is marked in VLR as attach once again wit location registration procedures triggering between VLR and HLR.

    #57197 Reply
    Viki
    Guest

    Hi, Pan.
    Yes, you are right ๐Ÿ™‚
    Interersting case when a MS went out of coverage, in a while it was purged from the VLR and after this it gets the coverege at the same place. During this time the MS was not turned off and on. So there could be only periodic Location Update for the VLR where it was purged. How it will be treated by the VLR?

    #57198 Reply
    Pan
    Guest

    Hello, Viki! If MS returned under the coverage of the same Location Area without switch off/switch on procedures then Purge state in the VLR and HLR is stored until any outgoing activities of that MS takes place (periodic LU, MOC, MO_SM etc). After that VLR sends LR request to the HLR and the latter inserts subscriber’s data in the VLR.

    #57199 Reply
    Viki
    Guest

    Should not the record of this MS be deleted from the VLR and TMSI released? In this case if it is possible to make a MO call for this MS? There should be Location Update procedure, shouldn’t it?

Viewing 15 posts - 1 through 15 (of 29 total)
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