Cisco Cisco ASR 5000
Direct Tunnelling for the S4-SGSN
▀ How It Works
▄ SGSN Administration Guide, StarOS Release 18
Table 17.
New SRNS Behaviors
Target RNC
DT Status
Direct
Forwarding
S-GW
Relocation
Behavior
Supported
No
No
Relocation Request with SGW S12U FTEID received in Forward Relocation Request.
SGSN includes RNC U FTEID in Forward Relocation Response. RNC U FTEID is
also sent in Modify Bearer Request with DTF flag set.
SGSN includes RNC U FTEID in Forward Relocation Response. RNC U FTEID is
also sent in Modify Bearer Request with DTF flag set.
Supported
Yes
No
Relocation Request with SGW S12U FTEID received in Forward Relocation Request.
In Forward Relocation Response RNC U FTEID is included. And in Modify Bearer
Request RNC U FTEID is sent and DTF flag is set.
In Forward Relocation Response RNC U FTEID is included. And in Modify Bearer
Request RNC U FTEID is sent and DTF flag is set.
Supported
No
Yes
Create Session Request with DTF flag set and no user plane FTEID. Relocation
Request is sent is SGW S12U FTEID received in Create Session Response. Even if
SGW sent S4U FTEID in CSR Response we will internally treat that as S12U FTEID
and continue the relocation. Create Indirect Data Forwarding Tunnel Request is sent
with RNC FTEID received in Relocation Request Acknowledge.In Forward
Relocation Response SGW DL U FTEID received in Create IDFT response is sent.
Modify Bearer Request is send with DTF set and RNC U FTEID.
Request is sent is SGW S12U FTEID received in Create Session Response. Even if
SGW sent S4U FTEID in CSR Response we will internally treat that as S12U FTEID
and continue the relocation. Create Indirect Data Forwarding Tunnel Request is sent
with RNC FTEID received in Relocation Request Acknowledge.In Forward
Relocation Response SGW DL U FTEID received in Create IDFT response is sent.
Modify Bearer Request is send with DTF set and RNC U FTEID.
Supported
Yes
Yes
Create Session Request with DTF flag set and no user plane FTEID. Relocation
Request is sent with SGW S12U FTEID received in Create Session Response. Even if
SGW sent S4U FTEID in CSR Response we will internally treat that as S12U FTEID
and continue the relocation. In Forward Relocation Response RNC FTEID is sent and
Modify Bearer Request is sent with DTF flag set and RNC U FTEID
Request is sent with SGW S12U FTEID received in Create Session Response. Even if
SGW sent S4U FTEID in CSR Response we will internally treat that as S12U FTEID
and continue the relocation. In Forward Relocation Response RNC FTEID is sent and
Modify Bearer Request is sent with DTF flag set and RNC U FTEID
Old SRNS with Direct Data Transfer
This scenario includes SRNS relocation between two SGSNs and hence IDFT is not applicable. Data will be forwarded
between the source and target RNCs directly. Forward Relocation Request is sent with S12U FTEID.
between the source and target RNCs directly. Forward Relocation Request is sent with S12U FTEID.