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LLC Re-transmission

Viewing 10 posts - 1 through 10 (of 10 total)
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  • #68105 Reply
    Vicky_RF
    Guest

    Dear All,

    Pls help me,what is the LLC Re-transmission ,is at at the RLC layer??

    #68106 Reply
    pix
    Guest

    hi,

    it’s probably at llc layer ! LLC is managed by the SGSN.

    but (as far as i recall) LLC is not supposed to retransmit data (except some signalling, i believe). The retransmission is done at higher layers (applications, such as TCP).

    regards
    pix

    #68107 Reply
    Vicky_RF
    Guest

    Thanks Pix,should we need to consider this LLC Re-transmission in our UL/DL TBF Establishment Success Rate formula.

    #68108 Reply
    pix
    Guest

    how would the llc retransmission impact the TBF establishment ?

    please, more details !

    regards
    pix

    #68109 Reply
    raj
    Guest

    LLC retransmission occurs at the LLC layer and not at the RLC layer.
    Have you ever wondered why there is an requirement of another logical link, i.e. LLC, above RLC, between the MS and SGSN?
    ——–
    There could scenario where LLC retransmissions will be required, for example, for an application that works in an unacknowledged mode and which do not have an error checking and correction mechanism on it own.
    ———
    Due to LLC retransmission, timer running at TCP layer may expire. This will make the TCP to re-send the Network PDU (NPDU), for whom an ack was awaiting, to the LLC layer , which could further add to a delay in the TBF establishment or even a dip in throughput.

    Hope above explains your concerns.

    -Raj/www.telecomspeaks.com

    #68110 Reply
    Vicky_RF
    Guest

    Thanx Raj,
    Do u have the data flow for the same.

    #68111 Reply
    pix
    Guest

    raj,

    are you saying that the application layer might force the LLC to work in an ack mode, thus enabling LLC retransmissions?

    Maybe I am wrong, but as far as i remember, LLC ack mode is enabled only for specific messages (flow control or signalling msg, or something like this).
    For user place, LLC is always unack.

    ==> no llc retransmission
    ==> no delay due to LLC retransmission

    cheers
    pix

    #68112 Reply
    Vicky_RF
    Guest

    Hi Pix,

    How are you

    LLC Transmission is happened due to resource re-allocation request made at RLC layer???

    #68113 Reply
    pix
    Guest

    hi vicky,

    no. But please expand your question, it looks like you are facing a problem ?

    cheers
    pix

    #68114 Reply
    Vicky_RF
    Guest

    Hi Pix,

    Actually I want to know when UL/DL LLC frame changes during the UL/DL GPRS TBF transmission at that time resource re-allocation request is made at RLC layer for UL/DL TBF.

    And also let me know how the LLC frame changes.

Viewing 10 posts - 1 through 10 (of 10 total)
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