Cisco Cisco ASR 5000
Serving GPRS Support Node (SGSN) Overview
▀ Features and Functionality
▄ SGSN Administration Guide, StarOS Release 18
Initial attach indicator bit in Update GPRS Location message, ISR information IE, if the UGL is sent for an
initial attach or for a inbound routing area update without ISR activation and the selected interface is Gr.
Initial attach indicator bit in Update Location Request message, ULR flags, if the ULR is sent for an initial attach
or for a inbound routing area update without ISR activation and the selected interface is S6d.
Configurable Pacing of PDP Deactivations on the S4-SGSN
The S4-SGSN now supports configurable pacing of PDP de-activations towards UEs due to path failures. Previously in
the S4-SGSN, the pacing of path failure delivery was started by the EGTP application and it used the generic session
manager pacing mechanism. The generic pacing mechanism performed 1000 path failure initiated PDP de-activations
per second per session manager. Since this may not be desirable for many operators based on their RAN's capability, the
S4-SGSN now supports the configurable pacing of PDP deactivations via the SGSN application (the same mechanism
used in the Gn/Gp SGSN).
the S4-SGSN, the pacing of path failure delivery was started by the EGTP application and it used the generic session
manager pacing mechanism. The generic pacing mechanism performed 1000 path failure initiated PDP de-activations
per second per session manager. Since this may not be desirable for many operators based on their RAN's capability, the
S4-SGSN now supports the configurable pacing of PDP deactivations via the SGSN application (the same mechanism
used in the Gn/Gp SGSN).
The existing
pdp-activation-rate command
in SGSN Global Configuration Mode can be used to configure the
pacing of PDP de-activations for both the connected-ready state and the idle-standby state.
This feature is included with the SGSN S3/S4 license. No additional feature license is required.
DNS SNAPTR Support
By default, the S4-SGSN supports the initiation of a DNS query after APN selection using a S-NAPTR query. The
SGSN resolves a P-GW by sending an APN-FQDN query to the DNS client. Similarly, the SGSN resolves the S-GW by
sending a RAI-FQDN query to the DNS client. The DNS Client then sends a query to the DNS server to retrieve
NAPTR/SRV/A records and return the S-GW or P-GW IP address to the SGSN.
SGSN resolves a P-GW by sending an APN-FQDN query to the DNS client. Similarly, the SGSN resolves the S-GW by
sending a RAI-FQDN query to the DNS client. The DNS Client then sends a query to the DNS server to retrieve
NAPTR/SRV/A records and return the S-GW or P-GW IP address to the SGSN.
On the S4-SGSN, an additional configurable is available that identifies the context where DNS lookup for EPC-capable
UEs must occur. This is accomplished by creating a call control profile that directs the system’s DNS client to perform
the lookup in the context where the SGSN’s DNS client is configured.
UEs must occur. This is accomplished by creating a call control profile that directs the system’s DNS client to perform
the lookup in the context where the SGSN’s DNS client is configured.
If the CLI configurable is not used, or removed, the S4-SGSN chooses the DNS client from the context where the EGTP
service is configured for performing P-GW DNS resolution, if the EGTP service is associated for a EPC capable UE.
service is configured for performing P-GW DNS resolution, if the EGTP service is associated for a EPC capable UE.
If the EGTP service is not present and the UE is EPC-capable, and if
apn-resolve-dns-query snaptr
is
configured in an APN profile, then the S4-SGSN uses the DNS client in the context where the SGTP service is present
for resolving a co-located P-GW/GGSN and selects the Gn interface.
for resolving a co-located P-GW/GGSN and selects the Gn interface.
S4-SGSN Statistics Support
Statistics have been added to provide information on S4-SGSN functionality.
The statistics added track information related to:
SGW Relocations
ISR Deactivations
Number of active PDPs using the S4 interface in 3G
S3 Interface Selection Statistics
Procedure Abort Statistics
GTPU Statistics
IDFT Statistics