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======Components and Interfaces======
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=====Logical Components of EPDG SCAT=====
  - **EPDG Core** - the main component responsible for coordinating modules and managing tunneling parameters, ensuring QoS;
  - **Authorization Module** (AM, Authorization Management) - manages authorization interfaces, with flexible scenario settings for integration with the operator's IS. Responsible for interaction with the operator's AAA server if available or can completely replace it for internal and external services;
  - **Tunnel Management Module** (TMM, Tunneling Management) - manages the binding of IPSec and GTP tunnels. Responsible for interaction with the operator's PGW, with flexible configuration scenarios for working with different interfaces.

=====Supported Interfaces=====
^  Input                                                                                ^^
| SWa (SWm)  | For external systems, such as TWAG. Applied in AAA-proxy case             |
| SWu        | From UE                                                                   |
| S6b        | From operator's PGW, for organizing flow from PGW to HSS on incoming call |

^  Output                                                                ^^
| SWx     | To HSS                                                        |
| SWm     | To AAA                                                        |
| S2b     | To PGW for signaling traffic                                  |
| S5/S8   | To PGW for signaling traffic (when S2b is unavailable)        |
| S2a     | To PGW in TWAN mode                                           |