OsmoGGSN: multiple instances: mention GTP port
Change-Id: I781feeb955ace17d93206bc98d12bc423584ce32
diff --git a/doc/manuals/chapters/running.adoc b/doc/manuals/chapters/running.adoc
index a242e36..ef899b5 100644
--- a/doc/manuals/chapters/running.adoc
+++ b/doc/manuals/chapters/running.adoc
@@ -39,3 +39,12 @@
ctrl
bind 127.0.0.2
----
+
+Also make sure to place each instance's GTP bind on a separate IP address (GTP
+uses a port number that is fixed in the GTP specifications, so it will not be
+possible to pick differing ports on the same IP address), like:
+
+----
+ggsn ggsn0
+ gtp bind-ip 127.0.0.2
+----