Cisco Cisco ASR 5000
Direct Tunnelling for the S4-SGSN
How It Works ▀
SGSN Administration Guide, StarOS Release 18 ▄
Intra SGSN Routing Area Update without SGW Change
For a Routing Area Update without an S-GW change with Direct Tunnel, the SGSN sends a Modify Bearer Request to
the S-GW with the RNC FTEID. The SGSN will establish RABs with the target RNC only if the RABs were present
with the source RNC.
the S-GW with the RNC FTEID. The SGSN will establish RABs with the target RNC only if the RABs were present
with the source RNC.
Figure 33. Routing Area Update Procedure without SGW Change
The table below includes detailed behaviors for a Routing Area Update without S-GW change.
Table 14.
Routing Area Update without S-GW Change Behavior Table
Scenario
Old
RNC
Status
Status
Old
RNC
RAB
RAB
Old RNC
DT Status
PLMN
Change
NEW RNC
DT Status
S-GW
Change
SGSN Action
Intra
RAU
RAU
Not
Present
Present
No
RAB
RAB
Supported
No
Supported
No
No RAB establishment with new RNC. No
Modify Bearer Request to S-GW
Modify Bearer Request to S-GW
Intra
RAU
RAU
Present
No
RAB
RAB
Supported
No
Supported
No
No RAB establishment with new RNC. No
Modify Bearer Request to S-GW
Modify Bearer Request to S-GW
Intra
RAU
RAU
Present
Some
RABs
RABs
Supported
Do not
care
care
Supported
No
Only the present RABs are established. MBR
sent to S-GW with the bearers with RABs that
are be modified and the rest released. The
bearers without RABs will be deactivated post
RAU. If PLMN changed then MBR will carry
the new PLMN ID.
sent to S-GW with the bearers with RABs that
are be modified and the rest released. The
bearers without RABs will be deactivated post
RAU. If PLMN changed then MBR will carry
the new PLMN ID.
Intra
RAU
RAU
Not
Present
Present
No
RAB
RAB
Supported
Yes
Supported
No
No RAB establishment with new RNC. MBR
is sent with only PLMN change. Bearer
Context will not carry any TEID.
is sent with only PLMN change. Bearer
Context will not carry any TEID.
Intra
RAU
RAU
Present
No
RAB
RAB
Supported
Yes
Supported
No
Same as above.