diff options
authorHarald Welte <laforge@osmocom.org>2020-11-20 16:59:36 +0100
committerHarald Welte <laforge@osmocom.org>2020-11-20 17:01:55 +0100
commit6da11244b0b2c9032bd27c5dc2993bb0af96b342 (patch)
parent46f610b3b4980d7248f8cd9c25b9e234f5ce0869 (diff)
cs7-config: Explain that A/Iu/Lb interfaces are reouted via STP
1 files changed, 11 insertions, 0 deletions
diff --git a/common/chapters/cs7-config.adoc b/common/chapters/cs7-config.adoc
index 25871ab..691c8ad 100644
--- a/common/chapters/cs7-config.adoc
+++ b/common/chapters/cs7-config.adoc
@@ -59,6 +59,17 @@ At the time of writing, SCCP/M3UA links involving Osmocom program are:
- IuPS-interface: OsmoHNBGW to OsmoSGSN
- Lb-interface: OsmoSMLC to OsmoBSC
+On the SCTP/IP level, those connections are actually all established from
+the respective program (BSC, MSC, HNBGW, SGSN, SMLC) to OsmoSTP. Hence,
+if you look at the traffic in a protocol analyzer like wireshark, at IP
+level, you will see each of those programs establishing an SCTP
+association from a random local IP to the well-known SCTP port for M3UA
+(2905) at the OsmoSTP.
+Those star-connections for M3UA/SCTP then are the transport network for
+higher level protocols like SCCP. OsmoSTP then acts as central router
+for SCCP-level message exchange between all the connected programs.
=== Connect to STP Instance
By default, an STP instance is assumed to listen on the default M3UA port