Gtp Tunnel With Pgw (Gtpv2) - Ruckus Wireless SmartCell Gateway 200 Reference Manual

GTP Tunnel with PGW (GTPv2)

This is the interface between the SCG with PGW. It is the control plane GPRS
tunneling protocol messages v2 for EPS interfaces (GTPv2-C) from the SCG and
PGW.
The S2a interface is used in controlling the signal between the SCG and PGW. It
also acts as a tunnel for end user data payload within the EPC network.
The GTP transmits user data packets and signaling messages between the SCG
and PGW. GTP encapsulates traffic and creates GTP tunnels, which act as virtual
data channels. A GTP tunnel is established between the SCG and PGW through
Create Session Request procedure for a data session initiated from the UE.
The SCG acts as trusted non-3GPP access network (TWAN) towards PGW with
S2a (GTPv2) interface. In case the operator EPC network, does not support the S2a
interface, the SCG can be statically configured to support S5 (GTPv2) interface, in
which case the SCG acts as serving gateway.
A GTP tunnel is identified by a pair of IP addresses and a pair of GTP TEIDs, where
one IP address and TEID is for the SCG (TWAN) and the other is for the PGW. The
TEID is a session identifier used by GTP protocol entities in the SCG and in the PGW.
GTP separates signaling from payload. Traffic is sorted onto a control plane (GTP-
C) for signaling and a user plane (GTP-U) for user data. GTP-C is a tunnel control
and management protocol and is used to create, modify and delete tunnels. GTP-
U is a tunneling mechanism, which provides a service for carrying user data packets.
On both planes, a GTP header encapsulates the data package, called GPDU, and
a path implemented by UDP/IP is used as bearer of the GTP traffic. The SCG
supports the following categories of GTP signaling traffic:
• Path management messages - The main purpose of these messages is to
supervise an UDP/IP path to ensure that connectivity failure can be detected on
time. This is managed by frequently sending GTP echo request or response
packets between the SCG and PGW.
• Tunnel management messages - These contain messages that establish, modify
and release GTP tunnels.
Figure 6 shows the deployment of the SCG in operator networks with 3G and EPC.
SmartCell Gateway 200 Tunneling Interface Reference Guide for SmartZone 3.4.1, 800-71380-001 Rev A
Core Network Protocols
Core Network Protocols
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