Cisco ASR 5000 Series Product Overview ▄  
Supported Logical Network Interfaces (Reference Points) 
The following figure displays the specific network interface between a Serving Gateway and other E-UTRAN network 
devices. 
 
Figure 156.  S-GW Interfaces in the E-UTRAN/EPC Network 
E-UTRAN
EPC
P-GW
S1-U
S5/S8
S11
Gxc
eNodeB
MME
PCRF
Signaling Interface
Bearer Interface
S-GW
 
The S-GW provides the following logical network interfaces in support of the E-UTRAN/EPC network: 
 
S4 Interface 
This reference point (not shown in the figure above) provides tunneling and management between the S-GW and an 
SGSN. 
 
S5/S8 Interface 
This reference point provides tunneling (bearer channel) and management (signaling channel) between the S-GW and 
the P-GW. The S8 interface is used for roaming scenarios. The S5 interface is used for non-roaming. 
Supported protocols: 
 
  Transport Layer: UDP, TCP