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France Telecom - Orange confidential
New Control Plane in 3GPP LTE/EPC Architecture for
On-Demand Connectivity Service
Siwar BEN HADJ SAID¹, Malla Reddy SAMA¹, Karine GUILLOUARD¹, Lucian SUCIU¹,
Gwendal SIMON², Xavier LAGRANGE² and Jean Marie BONNIN²
¹Orange Labs, France ²Télécom Bretagne, France
IEEE CloudNet’13
San Francisco, USA
11-13 Nov 2013
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Outline
I. Introduction & Background
II. OF-Based LTE/EPC Architecture
I. Architecture Description
II. Data Plane Establishment Procedure
III. On-Demand Connectivity Service
I. Resiliency
II. Load Balancing
IV. Implementation Challenges
V. Conclusion & perspectives
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Introduction
Mobile data traffic has
been growing at an
unprecedented rate over
the last few years.
Huge data traffic increase
and may cause signaling
storms in the network.
– Smartphones and
tablets generate 40% of
the data traffic and 99%
of the signaling traffic.
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LTE/EPC Architecture
External Packet
Data Networks
eNBUE
S1(GTP-U) S5 (GTP-U) SGi
S1
(S1-
AP)
S11 (G
TP
-C)
S6a (Diameter)
S5 (GTP-C)
Control Plane
User Plane
Evolved Packet Core
(EPC)E-UTRAN
MME HSS
SGW-D
SGW-C
PGW-D
PGW-C
eNB
The LTE/EPC has been designed to support only packet based
services.
The EPC has a flat, all-IP architecture with separation of control plane
and data plane.
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LTE/EPC Drawbacks
The initial attachments lead to a systematic establishment of the data
plane, even when there is no data traffic to be sent.
The data plane establishment procedure is unaware of the session
type.
The TEID values are locally allocated by each node new TEID
values should be exchanged for each node relocation.
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LTE/EPC Drawbacks - 2
SGW could be a bottle neck for possible user traffic congestion.
Network equipment failure.
This PGW can be
any where in all
over the world
Home
PDN
PGW
SGW
Internet
(Ex. SIPTO above RAN)
PGW IMS Semi-distributed
GW (SGi)
PGW
This PGW could be allocated per
county or region.
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OF-Based LTE/EPC Architecture
Separation of control and
data plane from SGW.
Replacing S1-MME and S11
interfaces with OF.
SGW-D represents an
advanced OF switch that is
able to en/decapsulate GTP
packets.
Unique TEID values per
session.
eNB keeps the same radio
functions.
eNB
eNB
OpenFlow Controller
MME SGW-C
S5 (G
TP-C
)OpenFlow
protocol
UE
S1(GTP-U)
S5 (GTP-U)
SGW-D
PGW-D
PGW-C
API
SGW-D
SGW-D
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On-Demand Connectivity Service
- Resiliency
- Load Balancing
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Resiliency – 3GPP LTE/EPC case
The 3GPP restoration procedure related to the SGW failure is not
transparent as it cuts off active sessions.
Session re-establishment of impacted users may generate
significant amount of signaling.
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Resiliency – OF-Based LTE/EPC case
Easily manage the active sessions during any SGW-D failures.
Less packet loss.
Centralized the TEID allocation function.
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Load Balancing – 3GPP LTE/EPC case
SGW and PGW selection is performed by the MME.
Offline weight factors in DNS server.
Proactive load balancing.
SGW could be a bottle neck for possible user traffic congestion.
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Load Balancing – OF-Based LTE/EPC case
Real time load statistics.
Free the overloaded SGW by moving some sessions seamlessly to
another SGW in the same domain.
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Implementation Challenges
SGW control and data plane separation.
Building mobile network based OF controller.
The OF protocol should be extended to transport the UE-MME
exchanges transparently, e.g.
– Authentication messages
– Mobility messages
Shifting all control plane entities into cloud platform.
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Conclusion & Perspectives
Proposal: OpenFlow-based control plane for LTE/EPC
architecture
– The SGW control plane is separated from the data forwarding plane
– The SGW control plane is centralized and uses the OpenFlow protocol to
remotely manage the SGW data forwarding plane
The proposed architecture ensures the on-demand connectivity service
even in critic situation such as network equipment failure and overload
situations
Perspectives:
– Realize a testbed to validate the resiliency and load balancing aspects in our
proposal
– Try to make standardize the OF-based LTE/EPC in ONF working groups.
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