Control And Data Interfaces - Cisco ASR 5000 Administration Manual

▀ Feature Description
On successful creation of the GTP tunnel, eWAG creates the association between the GGSN-assigned IP address and
the Wi-Fi IP address.
All IP data packets generated by the UE in the WLAN are directed to the eWAG. The eWAG NATs the outer source IP
address (Wi-Fi IP address) with the GGSN-assigned IP address (MPC IP address) and forwards it to the GGSN via the
GTP tunnel. The application servers in the PDN identify the UE by the GGSN-assigned IP address.
In the downlink direction, the eWAG NATs the outer destination address (MPC IP address) to the Wi-Fi IP address so
that it is correctly routed to the UE in the WLAN.

Control and Data Interfaces

eWAG supports the following control and data interfaces:
 WLC/Wi-Fi AAA – eWAG:
 Control Plane: The following RADIUS messages are supported on this interface:
 Data Plane: There is direct IP connectivity between WLC and eWAG. eWAG receives the original IP
 eWAG – GGSN (Gn'):
 PDP Activation Messages: The following messages are supported over the Gn' reference point:
▄ Cisco ASR 5000 Enhanced Wireless Access Gateway Administration Guide
12
 Accounting Start
 Accounting Interim
 Accounting Stop
 Disconnect Request
packets generated by UE in WLAN. There could be other network elements (routers) between WLC
and eWAG, which can provide Layer 2 or Layer 3 tunneling to route the WLAN-generated packets
across the public network.
Important:
ICMP Processing: ICMP packets in the downlink direction are remapped and sent to the UE.
 Create PDP Context Request / Response
 Update PDP Context Request / Response: eWAG-initiated Update PDP Context scenario is
supported as explained in the Session Update Call Flow section.
 Delete PDP Context Request / Response
 Error Indication
 Version Not Supported
 GTP Payload Forwarding
 GTP Echo
In this release, eWAG does not support Tunneling (IP over GRE).
Enhanced Wireless Access Gateway Overview
OL-28188-02