Cisco Cisco ASR 5000
Serving GPRS Support Node (SGSN) Overview
▀ Features and Functionality
▄ SGSN Administration Guide, StarOS Release 18
Procedure
Gn/Gp SGSN
S4-SGSN
New Inter SGSN RAU for a
PMM-IDLE subscriber
without a change of interface
PMM-IDLE subscriber
without a change of interface
1. Uses the PDP context prioritized
order in the SGSN Context Response
to select high priority PDP contexts
in the case of resource limitations at
the new SGSN.
to select high priority PDP contexts
in the case of resource limitations at
the new SGSN.
2. The SGSN ends the UPCQ to GGSN.
1. Performs the S-GW selection
procedure.
2. Uses ARP to prioritize EPS bearers. In
GTPv1 the PDP contexts sent in SGSN
context response will be in prioritized
order. But such an order is not defined
for sending EPS bearers in Context
Response. The idea is to use to ARP
for prioritization. PDP prioritization
for EPS bearers is not supported.
context response will be in prioritized
order. But such an order is not defined
for sending EPS bearers in Context
Response. The idea is to use to ARP
for prioritization. PDP prioritization
for EPS bearers is not supported.
3. The new S4-SGSN alerts of any
change in S-GW through the Context
Ack to the old S4-SGSN. The PMM
module will wait until the S-GW
selection procedure is complete at the
new S4-SGSN to alert of the context
ack.
Ack to the old S4-SGSN. The PMM
module will wait until the S-GW
selection procedure is complete at the
new S4-SGSN to alert of the context
ack.
New Inter SGSN RAU for a
PMM-CONNECTED
subscriber
PMM-CONNECTED
subscriber
Where “old” is S4-SGSN and “new” is SGSN
(Gn/Gp):
(Gn/Gp):
1. The new SGSN receives PDP
contexts in the SGSN Context
Response in prioritized order.
Response in prioritized order.
2. RABs will be established at the new
SGSN based on the ASI bit value for
each PDP.
each PDP.
Where “new” is S4-SGSN and “old” is SGSN
(Gn/Gp):
(Gn/Gp):
1. The new S4-SGSN receives PDP
contexts in the Context Response.
There is no prioritized order. ARP is
used to prioritize. PDP prioritization
for EPS bearers is not supported.
There is no prioritized order. ARP is
used to prioritize. PDP prioritization
for EPS bearers is not supported.
2. New S4-SGSN performs S-GW
selection.
3. The new S4-SGSN cannot establish
RAB as there is no ASI bit in the
GTPv2 Context Response. The
assumption is that the Context Req /
Response is used only for IDLE mode
handover, and that for connected mode
handover, the SRNS relocation
procedure should be used.
GTPv2 Context Response. The
assumption is that the Context Req /
Response is used only for IDLE mode
handover, and that for connected mode
handover, the SRNS relocation
procedure should be used.
New – SGSN PMM-
CONNECTED / PMM-IDLE
subscriber handover with
interface change
CONNECTED / PMM-IDLE
subscriber handover with
interface change
Where “old” is S4-SGSN and “new” is SGSN
(Gn/Gp):
(Gn/Gp):
1. The new S4-SGSN sends a GTPv1
SGSN Context Request and receives
the PDP contexts mapped from EPS
bearers in the SGSN context
response.
the PDP contexts mapped from EPS
bearers in the SGSN context
response.
2. The old SGSN will establish an inter-
SGSN tunnel for transferring queued
packets.
packets.
Where “old” is SGSN (Gn/Gp) and “new” is
S4-SGSN:
S4-SGSN:
1. The new S4-SGSN sends a GTPv1
SGSN context request, after learning
that the old SGSN is an SGSN
(Gn/Gp) based on a DNS S-NAPTR
response.
that the old SGSN is an SGSN
(Gn/Gp) based on a DNS S-NAPTR
response.
2. The new S4-SGSN will continue to use
the Gn interface for the PDPs.
Conversion of PDPs to S4-SGSN is not
supported at this time.
Conversion of PDPs to S4-SGSN is not
supported at this time.