Cisco Cisco ASR 5000
Direct Tunnelling for the S4-SGSN
How It Works ▀
SGSN Administration Guide, StarOS Release 18 ▄
Figure 34. Routing Area Update Procedure with SGW Change
The table below includes detailed behaviors for a Routing Area Update with S-GW change.
Table 15.
Routing Area Update with S-GW Change Behavior Table
Scenario
Old
RNC
RNC
Status
Old
RNC
RNC
RAB
Old RNC
DT Status
DT Status
PLMN
Change
Change
NEW RNC
DT Status
DT Status
S-GW
Change
Change
SGSN Action
Intra RAU: Both RNCs support Direct Tunnel. SGW relocation
Intra
RAU
RAU
Not
Present
Present
No
RAB
RAB
Supported
Do not
care
care
Supported
Yes
Send CSR request to new S-GW with DTF flag
but no S4U / S12U FTEID. S-GW will send its
S12U TEID that SGSN stores as part of DP's
remote TEID. SGSN will not initiate any MBR
request to S-GW since no RABs are established
with new RNC. If S-GW subsequently gets
downlink data, SGSN will get DDN and
establish RABs and send MBR.
but no S4U / S12U FTEID. S-GW will send its
S12U TEID that SGSN stores as part of DP's
remote TEID. SGSN will not initiate any MBR
request to S-GW since no RABs are established
with new RNC. If S-GW subsequently gets
downlink data, SGSN will get DDN and
establish RABs and send MBR.
Intra
RAU
RAU
Present
No
RAB
RAB
Supported
Do not
care
care
Supported
Yes
Same as above.
Intra
RAU
RAU
Present
Some
RABs
RABs
Supported
Do not
care
care
Supported
Yes
Send CSR request to new S-GW with DTF flag
but no S4U / S12U FTEID. S-GW sends its
S12U TEID. RABs that are present will be
established with new RNC. MBR will be
initiated only with those RABs that are present;
rest of bearers to be removed.
but no S4U / S12U FTEID. S-GW sends its
S12U TEID. RABs that are present will be
established with new RNC. MBR will be
initiated only with those RABs that are present;
rest of bearers to be removed.
Intra RAU: Old RNC does not support Direct Tunnel. SGW relocation