Virtual Apn Support; Offline Charging Support - Cisco ASR 5000 Administration Manual
Enhanced wireless access gateway
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Also See for ASR 5000:
- Administration manual (466 pages) ,
- Installation manual (294 pages) ,
- Installation procedure (8 pages)
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▀ Feature Description
On successful creation of the GTP tunnel, the R-eWAG creates the association between the GGSN-assigned IP address
and the Wi-Fi IP address with static NAT support. The binding between the Wi-Fi IP address and GGSN IP address for
a subscriber is maintained by R-eWAG/NAT.
In the uplink direction, the R-eWAG accepts Layer 3 Wi-Fi packets, which are translated by NAT. The Source IP
address, which is the Wi-Fi IP address, is translated to the GGSN-assigned IP address. The translated packet is then
encapsulated into GTP tunnel and forwarded to the GGSN.
In the downlink direction, the R-eWAG de-capsulates the GTP packets and translates the destination IP address, which
is the GGSN IP address, to the Wi-Fi IP address and then forwards the packets to the Wi-Fi network.
The R-eWAG + NAT/ALG supports the ability to apply the FTP, SIP, RTSP, PPTP, and H323 ALG on the subscriber's
IP flows.
Important:
R-eWAG service configuration requires rulebase configuration with NAT ALG enabled, IN and OUT ACL in APN, and
Firewall-and-NAT policy specified in the APN or rulebase. For R-eWAG + GGSN combo deployments, virtual-APN
configuration is required to separate the rulebases required for R-eWAG (for NAT) and GGSN (for DPI, NAT, P2P, and
others).
Virtual APN Support
The Virtual APN feature allows operators to use a single APN to configure differentiated services. The APN that is
supplied by the R-eWAG is evaluated by the GGSN in conjunction with configurable parameters. Then the GGSN
selects an APN configuration based on the supplied APN and those configurable parameters.
Important:
the rulebases required for R-eWAG (for NAT) and GGSN (for DPI, NAT, P2P, and others) work without any issues.
For more information on virtual-APN support in R-eWAG + GGSN combo deployments refer to the
Limitations
section.
Offline Charging Support
Offline Charging is a process wherein charging information is collected concurrently with resource usage. The charging
information is then passed through a chain of logical charging functions, and the CDR files are generated by the
network, which are then transferred to the network operator's Billing Domain.
The CTF (an integrated component in each charging relevant NE) generates charging events and forwards them to the
CDF. The CDF, in turn generate S-CDRs, which are then transferred to the CGF. Finally, the CGF create S-CDR files
and forwards them to the Billing Domain. The CTF and CDF are integrated in the R-eWAG. However, the CGF may
exist as a physically separate entity or integrated to the R-eWAG. If the CGF is external to the R-eWAG, then the CDF
forwards the CDRs to the CGF across the Gz/Wz interface (using GTPP protocol).
In the ASR5000 chassis, R-eWAG is integrated with the CTF and CDF functions and it generates S-CDR based on the
triggered events and sends the same to the CGF over the Gz/Wz interface. Note that the S-CDR format is used by
SGSN, and is now used for R-eWAG as well.
The R-eWAG Offline charging involves the following functionalities for WLAN 3GPP IP Access:
Charging Trigger Function
Charging Data Function
▄ Cisco ASR 5000 Enhanced Wireless Access Gateway Administration Guide
24
eWAG call requires NAT configuration. Without NAT, R-eWAG call will not setup. For NAT/ALG,
For R-eWAG + GGSN combo deployments, the virtual-APN configuration is required to ensure that
RADIUS-based Enhanced Wireless Access Gateway Overview
Dependencies and
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