Quality Of Service Profile Selection; Ggsn Selection; Ggsn Failover Case; Network Address Translation And Application Level Gateway Support - Cisco ASR 5000 Administration Manual
Enhanced wireless access gateway
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- Administration manual (466 pages) ,
- Installation manual (294 pages) ,
- Installation procedure (8 pages)
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RADIUS-based Enhanced Wireless Access Gateway Overview
Quality of Service Profile Selection
If the "3GPP-GPRS-Negotiated-QoS-Profile" AVP is not supplied in Accounting-Start Request message, a default
Quality of Service (QoS) profile is used. This value is hardcoded to maximum values in the QoS profile as defined in TS
24.008.
GGSN Selection
In this release, R-eWAG assumes the presence of Operator Identifier (OI) in "mncXXX.mccYYY.gprs" format in APN
received in the "Called-Station-ID" AVP. However, no validation of the presence of OI is made. The "Called-Station-
Id" AVP content is sent to DNS for GGSN IP address resolution without any modification. The same is applicable if the
"Called-Station-Id" AVP is not present and the default APN configuration in the R-eWAG service is used. Note that in
both these cases only the Network Identifier (NI) part has to be configured as APN at R-eWAG.
GGSN Failover Case
In case the DNS server returns more than one GGSN address for the given APN, and if Create PDP Context Request to
GGSN fails due to the GGSN being unreachable, then the next GGSN address from the list of addresses will be tried.
The next GGSN address will also be tried in case the GGSN rejects Create PDP Context Request due to any of the
following reasons:
No resources available
All dynamic PDP addresses are occupied
No memory available
Missing or unknown APN
System failure
Unknown PDP address or PDP type
All decode errors at peer, such as "Mandatory IE incorrect", "Mandatory IE missing", "Optional IE incorrect",
and "Invalid message format"
The next GGSN will be tried until either the address list is exhausted or PDP context activation succeeds. Note that the
R-eWAG is concerned with only the first five reasons from the above list to retry the next GGSN.
The maximum limit for the number of GGSN addresses that can be retried is 31.
R-eWAG also has the ability to locally select a GGSN. This would be used in case a DNS server is unavailable or
unreachable. The GGSN IP addresses can be configured under the R-eWAG service in the CLI.
Network Address Translation and Application Level Gateway Support
For the interworking between trusted WLANs and 3G MPC, the R-eWAG uses Network Address Translation (NAT) in-
line service support to map Wi-Fi IP addresses to MPC IP addresses and vice versa.
A UE connected to Wi-Fi has IP address allocated from Wi-Fi. It will also have another IP address allocated from the
MPC. The translation involves remapping of the Wi-Fi IP address to the MPC IP address and vice versa in the IP header
as well as in the payload (Application Level Gateway (ALG)).
Cisco ASR 5000 Enhanced Wireless Access Gateway Administration Guide ▄
Feature Description ▀
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