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MTP2 – Alignment procedure

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  • #36553
    Ng Kwong Kuek

    I am doing the emergeny alignment.Assuming i am pt code 1 with another pt code 2.

    After receiving from pt code 2 (LSSU FF FF 01 02 – emergency alignment, I responded with the same FF FF 01 02). Then pt code 2 will send me FISU (FF FF 00); I responded with the same FF FF 00. Pt code send me SLTM FF 80 16 81 ….etc; I responded with SLTM.

    Then I got SLTA from pt code 2 (80 81 16 81 …etc); I responded with the same.

    At this point onwards pt code 2 keep sending me FISU of 80 81 00 and subsequently 81 81 00; how should i acknowledge these FISUs; I responded with the same values; the link went into changeback procedure but went out of service again


    be careful in such point – sltm and slta from both exhanges must be in the same network – nat0(10bin) or nat1(11 bin) or int0(00bin) . Another problem – be careful with point codes.


    Hi Dmitry

    thanks for your reply. Assuming

    point code 2 sends me (point code 1) a SLTM

    Point Code 1 Point Code 2

    SLTA (808116810240000021F0112233445566778899AABBCCDDEEFF)

    Are the above hex values (SLTA) for the BSN/BIB & FSN/FIB correct? Or should I send 8080 instead of 8081



    You have to take care while replying to the msgs, as FISU don’t require the FSN/BSN to be incremented while on the other side LSSU, MSU requires it to be.

    The second thing, if you receive SLTM ( test msg ) should reply with in timeout period of the other end. If times out the other end re-enters into aliengment procedure.

Viewing 4 posts - 1 through 4 (of 4 total)
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