▄ Cisco ASR 5000 Series Product Overview 
  Tunneling: 
  GTP: IPv4 or IPv6 GTP-C (signaling channel) and GTP-U (bearer channel) 
  Network Layer: IPv4, IPv6 
  Data Link Layer: ARP 
  Physical Layer: Ethernet 
 
S-GW S5/S8 (GTP) P-GW
L1/L2
GTP-C/U
IPv4 / IPv6
IPv4 / IPv6
Transport
L1/L2
IPv4 / IPv6
IPv4 / IPv6
Transport
UDP UDP
GTP-C/U
 
 
S1-U Interface 
This reference point provides bearer channel tunneling between the eNodeB and the S-GW. It also supports eNodeB 
path switching during handovers. 
 
Supported protocols: 
 
  Transport Layer: UDP, TCP 
  Tunneling: IPv4 or IPv6 GTP-U (bearer channel) 
  Network Layer: IPv4, IPv6 
  Data Link Layer: ARP 
  Physical Layer: Ethernet