ws@tools.uucp (Wolfgang Solfrank) (01/26/91)
I'm trying to make sense out of Annex B and C of the Blue Book Recommendation X.25. According to Annex B, there is no transition between states r2 and r3, p6 and p7 and d2 and d3 resp. The interface goes from r2 to r1 on transfer of a restart indication, from p6 to p1 on transfer of a clear indication and from d2 to d1 on the transfer of a reset indication. But in Annex C it says the DCE should, when receiving some invalid packet, send a restart indication with "Local procedure error" and enter state r3. Similarly the DCE should send a clear indication in state p6 and enter state p7, and a reset indication in state d2 and enter state d3. The description in the recommendation itself seem to favor the interpretation according to Annex B: 3.3.3 Restart collision Restart collision occurs when a DTE and a DCE simultaneously transfer a restart request and a restart indication packet. Under these circumstances, the DCE will consider that the restart is completed. The description of the procedures for clear collision in 4.1.9 and for reset collision in 4.4.3.3 are similarly phrased. (These even explicitly specify a state transition to state p1 and d1 resp.) All this seems to imply that Annex C is wrong, but as an annex "forms an integral part of the Recommendation" I want to be shure. Can someone shed a little light on this? -- ws@tools.uucp (Wolfgang Solfrank, TooLs GmbH) +49-228-230088