AW: LAPDm bug: How to exit LAPDm_STATE_TIMER_RECOV state

Andreas.Eversberg Andreas.Eversberg at
Mon Oct 25 07:50:53 UTC 2010

> The timer recovery condition is only cleared if the data link layer
> entity receives a valid supervisory frame response
> with the F bit set to "1". If the N(R) of this received supervisory
> frame is within the range from its current state variable
> V(A) to its current send state variable V(S) inclusive, it shall set
> its send state variable V(S) to the value of the received
> N(R). Timer T200 shall be reset if the received supervisory frame
> response is an RR or REJ response with F bit set to
> "1". The data link layer entity shall then resume with I frame
> transmission or retransmission, as appropriate.
> Timer T200 shall be set if the received supervisory response is an RNR
> response, and the data link layer shall proceed
> with the enquiry process in accordance with subclause 5.5.5.

hi sylvain,

you are right. in case of an RR "response" (or an I frame) with the F
bit set to "1", there is no clearing of the "timer recovery state". in
other cases (RNR, REJ) it is handled.

i would like to test this with a prepared frame drop tonight. if this
works, i will commit it.



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