[asterisk-ss7] Two signaling links same linkset - SLS problem

Matthew Fredrickson creslin at digium.com
Mon Jan 21 15:15:58 CST 2008

Daniel Bichara wrote:
> Dear,
> Running 2 signaling links on the same linkset connected to different DPC
> produces wrong SLS on STD_TEST and second link did not align:
>                   - Port#1 (PC 1000) <- (quasi-associated) -> SPS 1201 
> asterisk (PC 333) -+
>                   - Port#2 (PC 2000) <- (quasi-associated) -> SPS 1202
> SPS 1201 and 1202 are quasi-associated mode SPS. Signaling channels are
> on channel 16 on link #1 and #2. SPS 1201 and 1202 are adjacent PC.
> During alignment tests, asterisk sends MSU message (STD_TEST) with SLS=1
> to PC 1202. Although, to this PC, SLS should be zero (the same as 1201)
> because they are running different PCs.
> If we run second PC as a different linkset (linkset #2), everything goes
> fine but we can not start calls on CICs from the other link.
> We are patching libss7 and chan_zap to relate CIC's (PVTs) to the OPC
> (333 this case) and not to the linkset. This way, the 2 different
> linksets can communicate to the CIC on both links because they run same
> OPC (333).
> Any comment or feedback is appreciated.

I just put in a provisional fix related to this in libss7.  The problem 
is that when I did the linkset association in libss7, I had assumed that 
when hooking up via multiple redundant links, that they would be within 
the same linkset and simply have different SLC codes.

To support this configuration in libss7 you must update to the most 
recent version which provides a way to support this type of 
configuration.  The way it is setup in zapata.conf is the same as if 
they were both in the same linkset (so probably the same configuration 
as you had before).
Matthew Fredrickson
Software/Firmware Engineer
Digium, Inc.

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