Cisco Cisco Packet Data Gateway (PDG)
SGSN Changes in Release 16
SGSN Enhancements for 16.0 ▀
Release Change Reference, StarOS Release 16 ▄
541
The specified Peer RNC.
The keyword
sessmgr
is a mandatory keyword. Specifying the
peer-nsei-id
or
peer-rnc-id
is optional.
When the
peer-nsei-id
or
peer-rnc-id
is not specified the global statistics are cleared. If the Session
Manager instance is specified, the RLF context statistics for that Session Manager are cleared. If the keyword
all
is configured the RLF statistics for all the Session Managers are cleared.
CSCzn60387 - [S4-SGSN] S4-SGSN shall support topology based SGW
selection
Feature Changes
Topological Gateway Selection for the S4-SGSN
During primary PDP context activation for a UE in an EPC network, the SGSN does P-GW selection first for the given
APN and then the SGSN selects the S-GW for the RAI FQDN.
APN and then the SGSN selects the S-GW for the RAI FQDN.
Topology-based S-GW / P-GW selection is a mechanism defined by 3GPP TS 29.303 to choose a gateway based on the
geographical (topological) proximity of the P-GW to the S-GW. The two being co-located would have the highest
priority. Topology-based selection is not allowed for roamers connected to HPLMN access points (Home Routed
Scenario).
geographical (topological) proximity of the P-GW to the S-GW. The two being co-located would have the highest
priority. Topology-based selection is not allowed for roamers connected to HPLMN access points (Home Routed
Scenario).
DNS S-NAPTR returns a candidate list of GW nodes for each of the DNS queries. 3GPP TS 29.303 provides an
algorithm to feed these candidate lists and choose the topologically closer nodes among them.
algorithm to feed these candidate lists and choose the topologically closer nodes among them.
The SGSN’s Topology-based GW Selection feature supports two levels of sorting, first level is degree and second level
is order/priority, where order is for NAPTR records and priority is for SRV Records. Degree has the highest preference.
is order/priority, where order is for NAPTR records and priority is for SRV Records. Degree has the highest preference.
When enabled with the new call control profile CLI (see below), the S4-SGSN can use topological selection of a GW
during any of the following call flows for 2G, 3G, or both:
during any of the following call flows for 2G, 3G, or both:
First Primary Activation
Subsequent Primary Activation
INTRA RAU
INTRA SRNS
NEW INTER SGSN RAU
NEW INTER SGSN SRNS
IRAT
With this release, the Gn/Gp-SGSN now supports S-NAPTR-based DNS query (see CSCub16578). The Gn/Gp-SGSN
can perform Topological Gateway Selection by using the DNS query to select a topologically closer GGSN or a co-
located PGW.
can perform Topological Gateway Selection by using the DNS query to select a topologically closer GGSN or a co-
located PGW.
For more details about this feature, refer to the Topology-based Gateway Selection feature section in the SGSN
Administration Guide.
Administration Guide.
Customer Impact: Selecting a co-located or topologically-close gateway (GW) node results in lower latency and
prevents unnecessary traversal of the packets in the network.
prevents unnecessary traversal of the packets in the network.