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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.

Where did you see that an I-Frame with the F bit set should clear the condition ?

you are right. i searched through the document. the I-Frame is handled during "timer recovery state", but this state is not cleared then. anyway: i am missing the description for "Receiving RR frames". A general description for RR, RNR, REJ is given in 5.5.3, but it does not describe what todo on a valid RR response with F bit set to "1". this is why i missed it.