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pespin has posted comments on this change by pespin. ( https://gerrit.osmocom.org/c/libosmo-sigtran/+/41410?usp=email )
Change subject: mtp: Support MTP-TRANSFER.req/ind of raw IPA messages ......................................................................
Patch Set 6:
(1 comment)
File include/osmocom/sigtran/protocol/mtp.h:
https://gerrit.osmocom.org/c/libosmo-sigtran/+/41410/comment/f0fc855c_cce328... : PS5, Line 30: *
does this mean we can no longer use libosmo-sigtran in national networks that use ni11 in routed MTP […]
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Regarding your question, several pointers: * This only really adds specific logic and is relevant for IPA ASPs, meaning for other kind of ASPs there's no behavior change here, and this SI can mean nothing there if we want to. * Since this is only used for IPA ASPs, this means that this SI is never really forwarded over the wire since IPA ASP doesn't forward any kind of SI information. Hence, this is only relevant in the local libosmo-sigtran stack for the user to be able to manage such traffic.
Then, we can differentiate between 2 scenarios: * endpoint (ASP, local distribution): Only picked/handled if the MTP user (app) registers a ss7_user for that SI. The SI value 2 (reserved) is picked on purpose to avoid colliding with other existing protocols (over IPA, which is anyway not standarized...). * STP (SG, routing): With the provided patch we actually improve the situation by allowing routing IPA messages (other than SCCP); before this patch they could only be picked through the dirty ss7_rx_nknown_cb() by the app, and otherwise they were always discarded. Now non-SCCP IPA messages are routed based on MTP, which I'd say is the expected behavior.
Ideally, somebody using SCCPLite would configure the NI with "Reserved for national use", since in the end it's using other SIs (MGCP, CTRL) which are not specified in the International network. In practice it doesn't matter since we are using IPA in those scenarios, where the SI is never sent over the network...In the end, this becomes another IPA particularity imho.