Hi Julian, I think I see this event happening often when I start a forward
with a forward partner from my FBB software. I see a slow-down of the
forward and my system sends several REJ frames. Then it gets back to
forwarding (or reverse forwarding) and goes awhile at normal 9600 baud
speed. The REJ frame problem can be seen easilly from my "listen" window
because of the slowdown that happens at the same time.
To be honest, I decided that these REJ frames are a normal part of ax25.
But your analysis makes it look like an error in the ax25 protocal. I am
not sure a maintainer exists for the ax25 protocal now.
On Fri, 7 May 1999, Julian Munoz Dominguez wrote:
} Hello,
}
} Who is the mainainer of ax25 in Linux ?
} Has ax25 changed from 2.0.36 to 2.2.x ??
}
}
} I think that I have found one error in the SDL diagrams in wich is based Linux
} code, wich is causing rejects.
}
} The conclusion is the following:
} In the Timer recovery State (4), I frame MUST NOT BE TX when we receive
} incoming Information frames (ore other frames wich are not Poll Responses) wich
} moves the TX window. AX25 v2.0 say that "clearly" (you know, that's not very
} clear, words and sentences are not so clean than a sdl diagram).
} What is bad is the "I Frame pops off queue" in the SDL diagram page 98 in ax25
} v2.2. This branch shouldn't be here.
}
} I explain that:
}
} In recovery state, you have send and Poll.
} This poll was sent because of the timeout of t1.
} But it is possible that if the peer has a "slow" persist/slottime, his frames
} are "being sent" while your timeout happens.
} When the timeout happens, you receive the frames that were "being sent", so
} that moves your TX window, and you TX more frames (That is the error!!!)
} The peer receive your Poll, and ack the frames that were BEFORE the last frames
} you have just transmited.
} You receive this poll and think that it has not received this last frames, and
} "Invoke Retransmission" box is called !! You retransmit this frames !!
} The peer receives duplicated set of frames ! So it send a REJ !!!
}
} So:
} 1) You have transmitted frames twice
} 2) That takes time, it's possible that in the middle another timeout happens !!
} 3) Very low throughput in this situation.
}
} 4) I also detect that some frames are received OUT OF SEQUENCE, causing
} Disconnects. I have not yet detected cause...
}
} On the other hand, if the poll bit of the last I frame is activated (which I
} think it must not, I have changed my sources to do that, and sincerly I'd like
} it to be disactivated in the kernel), what happened was very much more howfull,
} the same set of frames were TX a lot of times.
}
} Opinions ???
}
} --
} Saludos de Juli�n
} -.-
}
Best wishes
- Karl F. Larsen, [EMAIL PROTECTED] (505) 524-3303 -
