PDN Gateway Overview
Features and Functionality - Base Software ▀
Cisco ASR 5x00 Packet Data Network Gateway Administration Guide ▄
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address is part of the subscriber pool. In these scenarios, the P-GW supports the configuration of the first IP address of
the subscriber pool for use as the RADIUS NAS-IP address.
Important:
For more information on RADIUS AAA configuration, if you are using StarOS 12.3 or an earlier
release, refer to the
AAA and GTPP Interface Administration and Reference
. If you are using StarOS 14.0 or a later
release, refer to the
AAA Interface Administration and Reference
.
S-GW Restoration Support
Use of S-GW Restoration requires that a valid license key be installed. Contact your Cisco account representative for
information on how to obtain a license.
S-GW Restoration helps in handling the S-GW failure in the EPC network in a graceful manner. It allows affected
PDNs due to S-GW failure to be restored by selecting another S-GW to serve the affected PDNs, thus avoiding
unnecessary flooding of signaling for PDN cleanup.
S-GW Restoration is based on 3GPP Release 11. It requires enhancements at P-GW for maintaining the sessions in case
path failure is detected or when S-GW restart is detected via recovery IE on GTP-C signaling. P-GW shall ensure that
any dropped packets in this scenario are not charged and P-GW shall reject any bearer addition/modification request
received for the PDN connection maintained after the S-GW failure detection, till the time that PDN is restored again.
Once the session has been restored by the MME (i.e., P-GW receives a Modify Bearer Request from the restarted S-GW
or a different S-GW), P-GW shall resume forwarding any received downlink data and start charging them.
When subscriber is in S-GW restoration phase, all RARs (expect for Session Termination) will be rejected by PCEF. P-
GW will reject all internal updates which can trigger CCR-U towards PCRF. P-GW shall trigger a CCR U with AN-
GW-Change for the PDNs that are restored if the S-GW has changed on restoration.
Important:
Only MME/S4-SGSN triggered S-GW restoration procedure will be supported.
S-GW restoration
detection based on GTP-U path failure shall not be considered for this release. GTP-C path failure detection should be
enabled for enabling this feature.
MME/S4-SGSN shall be locally configured to know that P-GW in the same PLMN supports the S-GW restoration
feature. When this feature is enabled at P-GW, it shall support it for all S-GWs/MMEs.
Source IP Address Validation
Insures integrity between the attached subscriber terminal and the PDN GW by mitigating the potential for unwanted
spoofing or man-in-the-middle attacks.
The P-GW includes local IPv4/IPv6 address pools for assigning IP addresses to UEs on a per-PDN basis. The P-GW
defends its provisioned address bindings by insuring that traffic is received from the host address that it has awareness
of. In the event that traffic is received from a non-authorized host, the P- GW includes the ability to block the non-
authorized traffic. The P-GW uses the IPv4 source address to verify the sender and the IPv6 source prefix in the case of
IPv6.
