Cisco Cisco Packet Data Gateway (PDG)

 

provide network-based mobility management on behalf of the UEs attached to the network. With this approach, the 
attached UEs are no longer involved in the exchange of signaling messages for mobility. 

The LMA function on the SaMOG Gateway's CGW service and the MAG function on the WLCs maintain a single 
shared tunnel. To distinguish between individual subscriber sessions, separate GRE keys are allocated in the Proxy-MIP 
Binding Update (PBU) and Proxy-MIP Binding Acknowledgement (PBA) messages between the CGW service and the 
WLCs. To handle AAA server initiated disconnections, the CGW service supports RFC 5846 for Binding Revocation 
Indication (BRI) and Binding Revocation Acknowledgement (BRA) messaging with the WLCs. 

CGW connects 3G/4G subscribers to EPC/Inernet through the Trusted Wifi SSIDs served by EoGRE enabled 
Residential Gateways. CGW acts as the tunnel endpoint for the EoGRE tunnel initiated from the Residential Gateway. 
With the use of SSID-based WLAN access, the subscribers are authenticated based on the SSID they use in order to 
connect to the WLAN. The Residential-GW/WLC maintains a separate SSID for providing the 3G/4G access to help the 
UE in selecting the correct SSID for obtaining 3G/4G access through Wifi network. SaMOG (MRME) actas as the AAA 
server and DHCP server for the UE attaching to the WLAN network. This helps in processing all the control packets 
from the UE and maintaining the subscriber session to provide 3G/4G access. While acting as DHCP-Server, CGW 
creates the PDP-Context with GGSN/PGW to obtain the IP Address to be allocated to UE through DHCP-Reponse in 
the access side. The DHCP and data packets generated by UE will be tunneled over EoGRE by Residential-GW/WLC 
node to SaMOG. 

The Multi Radio Mobility Entity (MRME) service functions as a 3GPP Trusted WLAN AAA Proxy (TWAP), 
terminating the STa interface to the 3GPP AAA server and relays the AAA information between the WLAN IP access 
network and the AAA server, or AAA proxy in the case of roaming. 

The MRME service has the following key features and functions: 

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Relays the AAA information between the Wireless LAN Controllers (WLCs) and the 3GPP AAA server. 

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Supports EAP-over-RADIUS between the SaMOG Gateway and the WLCs to authenticate the WLAN UEs per 

RFC 3579. 

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Supports the Diameter-based STa interface between the 3GPP AAA server/proxy and the SaMOG Gateway per 

3GPP TS 29.273 V11.4.0. 

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Supports the exchange of EAP messages over the STa interface per RFC 4072. 

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Functions as a RADIUS accounting proxy for WLC-initiated accounting messages as per RFC 2866. 

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Supports RADIUS Dynamic Authorization Extensions per RFC 3576 to handle HSS/AAA-initiated detach and 

Diameter re-authorization procedures. 

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Supports authentication between the WLAN UEs and the 3GPP AAA server using EAP-AKA, EAP-AKA', and 

EAP-SIM. 

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Supports static and dynamic P-GW selection after the authentication procedures as per 3GPP TS 29.303 v 

11.2.0. 

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Support for PDN type IPv4. 

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Maintains a username database to re-use existing resources when the CGW service receives PMIPv6 and EoGRE 

procedures initiated by the WLCs. 

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Interacts with the CGW service to provide user profile information to establish the GTP-variant S2a/Gn interface 

towards the P-GW/GGSN per 3GPP TS 29.274 and 3GPP TS 29.060..