Pdg/Ttg Logical Network Interfaces (Reference Points) - Cisco ASR 5000 series Product Overview

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▀ Network Deployment(s) and Interfaces

PDG/TTG Logical Network Interfaces (Reference Points)

The following table provides descriptions of the logical network interfaces supported by the PDG/TTG in a

GPRS/UMTS data network.

Table 68. PDG/TTG Logical Network Interfaces

The Wu reference point is located between the WLAN UE and the PDG/TTG.

The Wu interface carries the secure IPSec tunnels between the UEs in the WLAN and the PDG/TTG. The IPSec

tunnels carry the ESP (Encapsulating Security Payload) packets between the UEs and the PDG/TTG.

The Wm reference point is located between the 3GPP AAA server and the PDG/TTG. The PDG/TTG uses this

reference point to retrieve tunneling attributes and UE IP configuration parameters.

The Gn' reference point is located between the TTG and the GGSN.

To provide PDG functionality in existing GGSN deployments, the TTG functions as an SGSN. For every IPSec

tunnel that is established between the TTG and a WLAN UE, the TTG initiates a PDP context and a corresponding

GTP tunnel over the Gn' interface to the GGSN. The TTG forwards the W-APN and IMSI of the WLAN UE to the

GGSN in the Create-PDP-Context-Request message.

The following messages are supported over the Gn' reference point:

Create PDP Context Request / Response

Update PDP Context Request / Response

Delete PDP Context Request / Response

Error Indication

Version Not Supported

GTP Payload Forwarding

The Gi reference point is located between the GGSN and the Packet Data Network (PDN) for WLAN IP access

when the PDG/TTG is in TTG mode.

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