▀ 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