Cisco Cisco Packet Data Gateway (PDG)

 

▄  SaMOG Administration Guide, StarOS Release 18 

The SaMOG Gateway acts as the termination point of the WLAN access network. The SaMOG service enables the 
WLAN UEs in the trusted non-3GPP IP access network to connect to the EPC network via Wireless LAN Controllers 
(WLCs). During configuration, the SaMOG service gets associated with two services: the Convergence Gateway 
(CGW) service and the Multi Radio Mobility Entity (MRME) service. These collocated services combine to enable the 
SaMOG Gateway functionality. 

The Convergence Gateway (CGW) service functions as a 3GPP Trusted WLAN Access Gateway (TWAG), terminating 
the S2a interface to the GGSN/P-GW and acts as the default router for the WLAN UEs on its access link. 

The CGW service has the following key features and functions: 

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Functions as a Local Mobility Anchor (LMA) towards the WLCs, which functions as a Mobile Access Gateway 

(MAG) with Proxy MIP capabilities per RFC 5213 and 3GPP TS 29.275 V11.5. 

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Enables the S2a GTPv2 interface towards the P-GW for session establishment per 3GPP TS 29.274 V11.5.0. 

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Enables the S2a PMIPv6 interface towards the P-GW for sessison establishment per 3GPP TS 29.275 V11.5.0. 

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Enables the Gn interface towards the GGSN for session establishment per 3GPP TS 29.060 V11.5.0. 

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Support for Layer 3 IP (L3IP) with out-of-band DHCP, and IP address assigned by the WLC (IP@W). 

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Routing of packets between the P-GW and the WLAN UEs via the Wireless LAN Controllers (WLCs). 

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Support for PDN type IPv4. 

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Interacts with the MRME service to provide user profile information to establish the GTP-variant S2a interface 

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

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Provides a Generic Routing Encapsulation (GRE) data path towards the WLCs per RFCs 1701 and 1702 for 

tunneling of data towards the WLCs. Also follows RFC 5845 for exchanging GRE keys with WLC-based 
PMIP signaling. 

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Receives and sends GTPU data packets towards the GGSN/P-GW per 3GPP TS 29.281 V11.5. 

The CGW service includes the following features and functions: 

Differentiated Services Code Point (DSCP) levels can be assigned to specific traffic patterns in order to ensure that data 
packets are delivered according to the precedence with which they are tagged. The DiffServ markings are applied to the 
IP header for every subscriber data packet transmitted in the downlink direction to the WLAN access network. The four 
traffic patterns have the following order of precedence: 

1.  Background (lowest) 
2.  Interactive 

3.  Streaming 

4.  Conversational (highest)