[asterisk-ss7] libss7: SLS in MTP3 link

[Horacio J. Peña]

Looking further, Q.704 2.3.4.1 says:

Messages not related to a signalling link may be assigned any Signalling
Link Code (SLC) to allow load sharing of the messages, or may be assigned
a default SLC such as 0000. They are routed in accordance with the normal
routing function, where the (SLC) is used as SLS for load sharing.

Q.704 9.1:

The MTP restart procedure uses the Traffic Restart Allowed (TRA) message
which contains:
– the label, indicating the originating signalling point and the
adjacent destination signalling point;
– the traffic restart allowed signal.

Q.704 15.2:

The Signalling Link Code (SLC) indicates the signalling link, connecting
the destination and originating points, to which the message is related.
If the message is not related to a signalling link, or another particular
code is not specified, it is coded 0000.


I am not sure if I understand it correctly, but it seems to me (and to
the spc 7000's developer) that TRA is not related to a signalling link,
so SLC may be coded as 0000 and should be accepted.


mtp.3, net_mng_receive:

struct mtp2 *winner = slc_to_mtp2(mtp2->master, rl->sls);

if (!winner) {
        /* Could not find the given slc */
        return 0;
}

should be changed to something like:

struct mtp2 *winner = net_mng_uses_sls(*headerptr) ? slc_to_mtp2(mtp2->master, rl->sls) : first_mtp2(mtp2->master);

(and the corresponding implementation of net_mng_uses_sls and first_mtp2)


Does this sound ok? What other NET_MNG messages aren't related to a signalling link ?

Thanks!
H

On Tue, May 25, 2010 at 12:32:31PM -0300, Horacio J. Peña wrote:
> Hola!
> 
> I'm having a problem getting a MTP3 link up. I'm not sure what SLC
> should be used but if I do the ss7_add_link with slc=1, it fails like:
> (my PC is 5000, adjpc is 7000)
> 
> STD_TEST OPC 5000 DPC 7000 SLS 1 H0: 1 H1: 1
> STD_TEST OPC 7000 DPC 5000 SLS 1 H0: 1 H1: 1
> STD_TEST OPC 5000 DPC 7000 SLS 1 H0: 1 H1: 2
> STD_TEST OPC 7000 DPC 5000 SLS 1 H0: 1 H1: 2
> NET_MNG  OPC 5000 DPC 7000 SLS 1 H0: 7 H1: 1 TRA
> NET_MNG  OPC 7000 DPC 5000 SLS 0 H0: 7 H1: 1 TRA (not recognized)
> 
> And if I use slc=0, it fails like:
> 
> STD_TEST OPC 5000 DPC 7000 SLS 0 H0: 1 H1: 1
> STD_TEST OPC 7000 DPC 5000 SLS 1 H0: 1 H1: 1
> No siganlling link available sending message!
> 
> STD_TEST OPC 7000 DPC 5000 SLS 1 H0: 1 H1: 1
> No siganlling link available sending message!
> 
> Am I missing something?
> 
> Thanks!
> -- 
> Horacio J. Peña
> horape at compendium.com.ar
> horape at uninet.edu

-- 
Horacio J. Peña
horape at compendium.com.ar
horape at uninet.edu