MMEs connect over Gn interface using GTPCv1 towards the SGSN in order to
exchange RIM PDUs by using "RAN Information Relay" GTPCv1 message type.
For more info, see 3GPP TS 29.060 sec 7.5.14.1 "RAN Information Relay"
In order to support it, this commit does the following:
* Uses new libgtp APIs to rx and tx RAN Information Relay messages. The
same "gsn" object is reused, ie. the local GTPCv1 socket address used
for exchanging messages against GGSN is reused.
* Adds a new "sgsn_mme_ctx" struct holding information about MMEs
allowed by the SGSN, each one containing information about the GTP
address it uses, the in/out routing based on TAI requests, etc. The
set of MMEs and their config can be set up using new VTY node introduced
in this commit.
* The RIM related code in SGSN is refactored to allow forwarding from
and to several types of addresses/interfaces.
Depends: osmo-ggsn.git Change-Id Iea3eb032ccd4aed5187baca7f7719349d76039d4
Depends: libosmocore.git Change-Id I534db7d8bc5ceb19a2a6866f07d5f5c70e456c5c
Related: SYS#5314
Change-Id: I396450b8d8b66595dab8ff7bf41cbf964bb40d93
Pau Espin
e5c8998f9c