manual: explain the PFCP port

Change-Id: I383befb226caa49e4a2577657806aef1ee11faa3
---
M doc/manuals/chapters/running.adoc
1 file changed, 15 insertions(+), 0 deletions(-)


git pull ssh://gerrit.osmocom.org:29418/osmo-hnbgw refs/changes/75/29075/1

diff --git a/doc/manuals/chapters/running.adoc b/doc/manuals/chapters/running.adoc
index 0bcca70..8074643 100644
--- a/doc/manuals/chapters/running.adoc
+++ b/doc/manuals/chapters/running.adoc
@@ -70,6 +70,7 @@
 
 - The SCCP/M3UA links are established by OsmoHNBGW contacting an STP.
 - The MGCP link is established by OsmoHNBGW contacting an MGW.
+- The PFCP link is established by OsmoHNBGW contacting a UPF.
 
 To run multiple OsmoHNBGW instances on the same SCCP routing, each HNBGW has to
 configure a distinct point-code, see <<configure_iucs_iups>>.
@@ -140,3 +141,17 @@
   mgw remote-port 2427
   mgw reset-endpoint rtpbridge/*
 ----
+
+==== Configure co-located User Plane Function
+
+OsmoHNBGW optionally supports relaying the GTP user plane via a co-located UPF,
+which is controlled by the PFCP protocol.
+
+The following example configures OsmoHNBGW to associate via PFCP with a UPF,
+ready to setup GTP tunnel relays.
+
+----
+hnbgw
+ pfcp
+  remote-addr 127.0.0.1
+----

