Product Description
Platform Requirements
Licenses
Network Deployment(s)
Serving Gateway in the E-UTRAN/EPC Network
Supported Logical Network Interfaces (Reference Points)
S1-U Interface
S4 Interface
S5/S8 Interface
S11 Interface
S12 Interface
Gxc Interface
Gz Interface
Features and Functionality - Base Software
IMPORTANT:
ANSI T1.276 Compliance
Bulk Statistics Support
IMPORTANT:
Circuit Switched Fall Back (CSFB) Support
Congestion Control
IMPORTANT:
IP Access Control Lists
IPv6 Capabilities
Management System Overview
IMPORTANT:
IMPORTANT:
Multiple PDN Support
IMPORTANT:
Online/Offline Charging
Online: Gy Reference Interface
Offline: Gz Reference Interface
Operator Policy Support
QoS Bearer Management
Subscriber Level Trace
Threshold Crossing Alerts (TCA) Support
IMPORTANT:
Features and Functionality - External Application Support
Web Element Manager
IMPORTANT:
Features and Functionality - Optional Enhanced Feature Software
Direct Tunnel
Inter-Chassis Session Recovery
IMPORTANT:
IP Security (IPSec) Encryption
IMPORTANT:
Lawful Intercept
Layer 2 Traffic Management (VLANs)
IMPORTANT:
Session Recovery Support
IMPORTANT:
How the Serving Gateway Works
GTP Serving Gateway Call/Session Procedures in an LTE-SAE Network
Subscriber-initiated Attach (initial)
Step | Description |
---|---|
1 | The UE initiates the Attach procedure by the transmission of an Attach Request (IMSI or old GUTI, last visited TAI (if available), UE Network Capability, PDN Address Allocation, Protocol Configuration Options, Attach Type) message together with an indication of the Selected Network to the eNodeB. IMSI is included if the UE does not have a valid GUTI available. If the UE has a valid GUTI, it is included. |
2 | The eNodeB derives the MME from the GUTI and from the indicated Selected Network. If that MME is not associated with the eNodeB, the eNodeB selects an MME using an MME selection function. The eNodeB forwards the Attach Request message to the new MME contained in a S1-MME control message (Initial UE message) together with the Selected Network and an indication of the E-UTRAN Area identity, a globally unique E-UTRAN ID of the cell from where it received the message to the new MME. |
3 | If the UE is unknown in the MME, the MME sends an Identity Request to the UE to request the IMSI. |
4 | The UE responds with Identity Response (IMSI). |
5 | If no UE context for the UE exists anywhere in the network, authentication is mandatory. Otherwise this step is optional. However, at least integrity checking is started and the ME Identity is retrieved from the UE at Initial Attach. The authentication functions, if performed this step, involves AKA authentication and establishment of a NAS level security association with the UE in order to protect further NAS protocol messages. |
6 | The MME sends an Update Location (MME Identity, IMSI, ME Identity) to the HSS. |
7 | The HSS acknowledges the Update Location message by sending an Update Location Ack to the MME. This message also contains the Insert Subscriber Data (IMSI, Subscription Data) Request. The Subscription Data contains the list of all APNs that the UE is permitted to access, an indication about which of those APNs is the Default APN, and the EPS subscribed QoS profile for each permitted APN. If the Update Location is rejected by the HSS, the MME rejects the Attach Request from the UE with an appropriate cause. |
8 | The MME selects an S-GW using the Serving GW selection function and allocates an EPS Bearer Identity for the Default Bearer associated with the UE. If the PDN subscription context contains no P-GW address the MME selects a P-GW as described in clause PDN GW selection function. Then it sends a Create Default Bearer Request (IMSI, MME Context ID, APN, RAT type, Default Bearer QoS, PDN Address Allocation, AMBR, EPS Bearer Identity, Protocol Configuration Options, ME Identity, User Location Information) message to the selected S-GW. |
9 | The S-GW creates a new entry in its EPS Bearer table and sends a Create Default Bearer Request (IMSI, APN, S-GW Address for the user plane, S-GW TEID of the user plane, S-GW TEID of the control plane, RAT type, Default Bearer QoS, PDN Address Allocation, AMBR, EPS Bearer Identity, Protocol Configuration Options, ME Identity, User Location Information) message to the P-GW. |
10 | If dynamic PCC is deployed, the P-GW interacts with the PCRF to get the default PCC rules for the UE. The IMSI, UE IP address, User Location Information, RAT type, AMBR are provided to the PCRF by the P-GW if received by the previous message. |
11 | The P-GW returns a Create Default Bearer Response (P-GW Address for the user plane, P-GW TEID of the user plane, P-GW TEID of the control plane, PDN Address Information, EPS Bearer Identity, Protocol Configuration Options) message to the S-GW. PDN Address Information is included if the P-GW allocated a PDN address Based on PDN Address Allocation received in the Create Default Bearer Request. PDN Address Information contains an IPv4 address for IPv4 and/or an IPv6 prefix and an Interface Identifier for IPv6. The P-GW takes into account the UE IP version capability indicated in the PDN Address Allocation and the policies of operator when the P-GW allocates the PDN Address Information. Whether the IP address is negotiated by the UE after completion of the Attach procedure, this is indicated in the Create Default Bearer Response. |
12 | The Downlink (DL) Data can start flowing towards S-GW. The S-GW buffers the data. |
13 | The S-GW returns a Create Default Bearer Response (PDN Address Information, S-GW address for User Plane, S-GW TEID for User Plane, S-GW Context ID, EPS Bearer Identity, Protocol Configuration Options) message to the new MME. PDN Address Information is included if it was provided by the P-GW. |
14 | The new MME sends an Attach Accept (APN, GUTI, PDN Address Information, TAI List, EPS Bearer Identity, Session Management Configuration IE, Protocol Configuration Options) message to the eNodeB. |
15 | The eNodeB sends Radio Bearer Establishment Request including the EPS Radio Bearer Identity to the UE. The Attach Accept message is also sent along to the UE. |
16 | The UE sends the Radio Bearer Establishment Response to the eNodeB. In this message, the Attach Complete message (EPS Bearer Identity) is included. |
17 | The eNodeB forwards the Attach Complete (EPS Bearer Identity) message to the MME. |
18 | The Attach is complete and UE sends data over the default bearer. At this time the UE can send uplink packets towards the eNodeB which are then tunnelled to the S-GW and P-GW. |
19 | The MME sends an Update Bearer Request (eNodeB address, eNodeB TEID) message to the S-GW. |
20 | The S-GW acknowledges by sending Update Bearer Response (EPS Bearer Identity) message to the MME. |
21 | The S-GW sends its buffered downlink packets. |
22 | After the MME receives Update Bearer Response (EPS Bearer Identity) message, if an EPS bearer was established and the subscription data indicates that the user is allowed to perform handover to non-3GPP accesses, and if the MME selected a P-GW that is different from the P-GW address which was indicated by the HSS in the PDN subscription context, the MME sends an Update Location Request including the APN and P-GW address to the HSS for mobility with non-3GPP accesses. |
23 | The HSS stores the APN and P-GW address pair and sends an Update Location Response to the MME. |
24 | Bidirectional data is passed between the UE and PDN. |
Subscriber-initiated Detach
Step | Description |
---|---|
1 | The UE sends NAS message Detach Request (GUTI, Switch Off) to the MME. Switch Off indicates whether detach is due to a switch off situation or not. |
2 | The active EPS Bearers in the S-GW regarding this particular UE are deactivated by the MME sending a Delete Bearer Request (TEID) message to the S-GW. |
3 | The S-GW sends a Delete Bearer Request (TEID) message to the P-GW. |
4 | The P-GW acknowledges with a Delete Bearer Response (TEID) message. |
5 | The P-GW may interact with the PCRF to indicate to the PCRF that EPS Bearer is released if PCRF is applied in the network. |
6 | The S-GW acknowledges with a Delete Bearer Response (TEID) message. |
7 | If Switch Off indicates that the detach is not due to a switch off situation, the MME sends a Detach Accept message to the UE. |
8 | The MME releases the S1-MME signalling connection for the UE by sending an S1 Release command to the eNodeB with Cause = Detach. |
Supported Standards
3GPP References
Release 8 Supported Standards
IETF References