Ip Address Allocation - Cisco ASR 5000 Administration Manual

▀ Product Overview
 D-eWAG-initiated UPC when new AP Location Information is received in the Accounting-interim
 Delete PDP Context Request/Response
 Error Indication
 Version Not Supported
 GTP Payload Forwarding
 GTP Echo
Important:
not happen.

IP Address Allocation

Dynamic IP Address Allocation
In this case, IP address for the UE connecting through WLAN is dynamically assigned by the GGSN. As explained
earlier, the UE initiates DHCP-Discover to obtain IP address after authentication. D-eWAG creates the PDP-Context in
response to this DHCP message. The End-user-address IE in the Create PDP Context Request message (indicating
dynamic address assignment by GGSN) is empty, which makes the GGSN allocate an IP address in the Response
message.
Static IP Allocation
Important:
with DHCP NAK.
The UE can sometimes request for an IP address using the "requested ip address" (option 50) field in DHCP message.
The scenario could be that the UE was earlier attached to the 3G network using macro-cell and is now connecting
through WLAN. Thus, it will try to retain the IP address it was allocated during 3G access by requesting the same
through DHPC message. In this case, D-eWAG will also request for the same IP address to GGSN by filling it in the
"End-user-address" IE in CPC Request. If the GGSN is not able to allocate the requested IP address, then D-eWAG
drops the call and DHCP-Offer message is not sent back.
▄ Cisco ASR 5000 Enhanced Wireless Access Gateway Administration Guide
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Note that only EUA Update rejection from D-eWAG will cause session teardown at GGSN and
subsequently D-eWAG session will be torn down through GGSN-initiated DPC. Also, note that EUA
Update is sent by GGSN in UPC Request only when GGSN had sent 0 IP address in EUA IE of the
CPC Response.
message for the session, and when COA with QoS update is received from 3GPP AAA.
UPC response handling scenarios:
 If GGSN responds with UPC failure with cause other than "non-existent", there will be no
QoS update for the D-eWAG session. The session persists in this case.
 If GGSN responds with UPC failure with cause set to "non-existent", the D-eWAG session
gets removed. Disconnect Message is sent to the WLC.
 If there is no UPC response from GGSN, GTP path failure is assumed and the D-eWAG
session is removed.
As the WLC cannot send 3gpp-qos, UPC from D-eWAG to GGSN for QoS change from WLC does
Static IP Allocation is not supported in this release. D-eWAG responds to DHCP static IP request
DHCP-based Enhanced Wireless Access Gateway Overview