diff --git a/cmake_targets/tools/epc.conf.in b/cmake_targets/tools/epc.conf.in
index 0f0ebbfd7f83baeeaec16f388ff627506abac5f3..3c43dc86fda00218093151ee3c70580656f5121f 100755
--- a/cmake_targets/tools/epc.conf.in
+++ b/cmake_targets/tools/epc.conf.in
@@ -1,3 +1,36 @@
+#                               Internet
+#                                  | 
+#         PGW_IPV4_ADDRESS_FOR_SGI | 
+# +-----------+-------+------------+---------------+--------------------------+
+# |host y     |       | PGW_INTERFACE_NAME_FOR_SGI |                          |
+# +-----------+       +------------+---------------+                          |
+# |                                |                                          |
+# |                           +----+----+   (HSS may run on this host         |
+# |                           | mme_gw  |    or on another one)               |
+# |                           +----+----+                                     |
+# |                                |                                          |
+# |              +-----------------+--------------------+                     |
+# |              | SGW_INTERFACE_NAME_FOR_S1U_S12_S4_UP |                     |
+# |              | MME_INTERFACE_NAME_FOR_S1_MME        |                     |
+# +----------------------------+---+--+---------------------------------------+
+#     MME_IPV4_ADDRESS_FOR_S1_MME  |  (S1-C and S1-U addresses/interfaces may be the same)  
+# SGW_IPV4_ADDRESS_FOR_S1U_S12_S4_UP 
+#                                  |
+#                                  |
+#                          a.b.c.d |
+# +---------------+------------+---+--+---------------------------------------+
+# |eNBx           |            | ethx |                                       |
+# +---------------+            +---+--+                                       |
+# |                                |                                          |
+# |                         +------+---------+                                |
+# |                         | lte-softmodem  |                                |
+# |                         |       or       |                                |
+# |                         | oaisim (1)eNB (x UEs)                           |
+# |                         +-------+--------+                                |
+# +---------------------------------+-----------------------------------------+
+#                                   |
+#                                   O (RF antenna)
+
 MME : 
 {