On Sat, 13 May 2006, Storer, Darren wrote: > the state of CICs can become unsynchronised between SS7 nodes although it > doesn't happen too often. Sometimes Node A thinks that a particular CIC is > "In Service Free" whilst Node B thinks that Node A didn't handle the last > call correctly and places the same CIC into a blocked state at a higher > application layer. Oh. There was a case I didn't think of... > When this situation occurs we normally use MML to "flex" the CICs by > manually taking each suspect CIC out of service and then returning it back > to service. I have seen that chan_ss7 appears to support these maintenance > messages but I haven't used them myself. Thats right. The user can unblock and block single circuits og groups of circuits manually if such a situation should occur. We implemented that feature to make users able to block a single E1 group for maintanance and unblock it when the maintanance is done, but it can probably be quite usefull if the nodes get out of sync. > When an SS7 node is started for the first time (cold start) it has no > knowledge of the state of the CICs as maintained by another SS7 node that it > is connected to. To synchronise the state of the CICs after a cold start it > is common to see many block and unblock messages (including Circuit Group > Resets) after the signalling links are aligned but before the route starts > to handle live traffic. I think chan_ss7 initially send a RESET message on all circuits. Anyway I hope Anton can make an ISUP dump of what is happening. If there is a bug in chan_ss7 which can make circuits hang, We would like to fix it :) Mvh. Jacob -- Jacob Tinning System Developer SIFIRA A/S
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