a virtual sdn-enabled lte epc architecture: a case …...technische universität münchen lehrstuhl...
TRANSCRIPT
Technische Universität München
Lehrstuhl für Kommunikationsnetze
Prof. Dr.-Ing. W. Kellerer
A Virtual SDN-enabled LTE EPC Architecture: a case study for S-/P-Gateways functions
11.November.2013
IEEE SDN for Future Networks and Services (SDN4FNS)
Arsany Basta Wolfgang Kellerer
Marco Hoffmann Klaus Hoffmann Ernst-Dieter Schmidt
Technische Universität München, Germany
Nokia Solutions and Networks, Munich, Germany
2
Data Traffic
eNodeB Signaling
X2
HSS PCRF OCS
S5/S8
S1-MME
MME
S10
S1-U
SGi
LTE Evolved Packet Core (EPC)
S6a
S7Gy
Gx
IP DomainP-GW
E-UTRAN
S11
S4
S-GW
UTRAN
SGSNNodeB RNC
Why change the current EPC architecture?
• Current EPC built out of monolithic entities on dedicated hardware
• Inflexible and lacks dynamic deployment
• Induces high cost to setup and maintain
3
How to change EPC architecture?
Network abstraction and flexible dynamic
programmability
Enabler for cost, energy consumption and space reduction by sharing, isolating and splitting of network functions [1]
Deployment platform for network functions
in software
[1] Network Operators, “Network Functions Virtualization“, SDN World Congress, Darmstadt, 2012
Cloud
Computing
4
What do NFV and SDN bring to the mobile core?
• Availability of incremental functionality additions to the network
• More flexibility in network management and control
• More elasticity in services scaling up/down
• Optimizing network configuration and topology
• Potential for reducing energy consumption
• Potential for a reduced capex and opex cost
5
EPC potential for virtualization?
Data Traffic
eNodeB Signaling
X2
HSS PCRF OCS
S5/S8
S1-MME
MME
S10
S1-U
SGi
S6a
S7Gy
Gx
IP DomainP-GW
S11
S4
S-GWSGSN
Operator’s Cloud Virtual EPC Components
Data Traffic
eNodeB
SignalingX2
HSS PCRF OCS
S5/S8
S1-MME
MME
S10
S1-U
SGi
S6a
S7Gy
Gx
IP DomainP-GW
S11
S4
S-GWSGSN
Transport Network
• Control-plane EPC nodes such as MME, HSS, PCRF, etc... impose not much effort to virtualize and migrate to an operator’s cloud
• Focus of our study is the data-plane coupled EPC nodes: S-GW and P-GW
6
Study steps
S-GW/P-GW functions analysis
Deployment architectures for the virtual SDN-enabled
S-GW and P-GW
SDN (OpenFlow) realization of derived functions
7
S-GW and P-GW derived functions
Control Signalng
Resources Allocation
Logic
Data-planeForwarding Rules
Data-plane Forwarding
GTP Matching
Charging Packet
Filtering
• Control-related functions can be integrated in an SDN controller
• Forwarding rules and data forwarding are fundamental functions of a basic OF switch
• Packet filtering (P-GW) can be provided based on the IP-five tuple [2] starting from OF 1.0
• Charging (P-GW) and GTP header matching (S-GW&P-GW) still need further evaluation
[2] 3GPP TS 23.203, “Policy and charging control architecture”, 2010
OpenFlow functions realization
Functions analysis
Deployment architectures
SDN (OF) realization
Functions analysis
SDN (OF) realization
8
Charging frameworks
• Module to collect offline
CDRs based on OF stats
• Optimize OF stats to match
different charging models
OF Switch OF Switch
OF Controller
OF Stats OF Stats
Offline CDR
Data Traffic
a) Offline charging
Counters Counters
OF Switch OF Switch
OF Controller
OF Stats
Charging Event
OF StatsEvent
trigger:Update Rules
Data Traffic
b) Online charging
Counters Counters
• Of switch keeps no data flow state
• Not possible to allocate triggers on switch
• Module to keep track of charging events
and update accordingly
Functions analysis
Deployment architectures
SDN (OF) realization
9
• GTP: IP-tunneling protocol used to encapsulate signaling and data in EPC
GTP matching frameworks
no matching rulesForward * to controller
GTP Module
OF “NE“
Dat
a tr
affi
c
OF Controller
Data Traffic
Rules from controller:in: * / out: middlebox
OF Controller
OF “NE“
Data Traffic
GTP
Middlebox
GTP rules
OF Controller
Rules from controller:GTP matching
GTP HW Customized
OF “NE+“
Data Traffic
OF Controller
Rules from controller:GTP matching
GTP SW
OF “NE+“
SW platformData Traffic
a) Controller handling GTP matching b) Middlebox handling GTP matching
c) NE+ with customized HW d) NE+ with SW platform
Functions analysis
Deployment architectures
SDN (OF) realization
10
X2
U-Plane Fabric
U-Plane Forwarding
Rules
Control Signaling
Resources Management
Logic
SDN API
Signaling
Data Traffic
SGSN
MME
eNodeB
GTPFiltering
Charging
S/P-GWs Control/Data-plane
Operator’s Cloud
IP PDN
Controller
NE
S1-MME
S11
S1-U
S4-U
S4-C
SGi
S10
Functions deployment possibilities?
1) Full Cloud Migration
still very centralized
All data traffic to cloud
SDN is not fully exploited
+ noticeable cost savings
+ control-plane scalability
+ standard OF switch
Functions analysis
Deployment architectures
SDN (OF) realization
11
Functions deployment possibilities?
2) Control-plane Cloud Migration
S10
X2
eNodeB
Charging U-Plane Fabric
U-Plane Forwarding
Rules
Control Signaling
Resources Management
Logic
SDN API
Signaling
Data Traffic
SGSN
MME
GTP
S/P-GWs Control-plane
IP PDN
Operator’s Cloud
Filtering
S/P-GWs Data-plane
Controller
NE+ / NE with Middlebox
S1-MME
S11
S1-U
S4-U
S4-C
SGi
enhanced OF switch
data overhead between
cloud and transport network
cost savings are reduced
+ control-plane flexibility
+ data-plane scalability
+ on-demand data plane resources
Functions analysis
Deployment architectures
SDN (OF) realization
12
Functions deployment possibilities?
3) Signaling control Cloud Migration
S10
X2
U-Plane Fabric
U-Plane Forwarding
Rules
Control SignalingSignaling
Data TrafficResources
Management Logic
SDN API
SGSN
MME
eNodeB
GTP
Charging
Filtering
S/P-GWs Control-plane
Operator’s Cloud
IP PDN
S/P-GWs Control/Data-plane
NE+ / NE with Middlebox
Controller
S1-MME
S11
S1-U
S4-U
S4-C
SGi
cloud migration is minimal
global network view is not
available anymore
+ possible less configuration delay
+ possible less data overhead
+ more resilient to cloud outages
or connection failures
Functions analysis
Deployment architectures
SDN (OF) realization
13
Functions deployment possibilities?
4) Scenario based Cloud Migration
S10
X2
Data Traffic
Classification Filters
U-Plane Fabric
U-Plane Forwarding
Rules
Control Signaling
Signaling
Resources Management
Logic
Resources Management
Logic
SDN API
SGSN
MME
eNodeB
GTP
ChargingFiltering
State Sync Updates
Operator’s Cloud
S/P-GWs Control/Data-plane
NE+ / NE with Middlebox
SDN
AP
I
Controller
S/P-GWs Control-plane
IP PDN
Data plane statistics
FilteringCharging
S1-MME
S11
S1-U
S4-U
S4-C
SGi
state sync overhead
orchestration between
functions is needed
additional cost induced
+ possible offloading of certain
EPC operations or service types
+ highest scalability and flexibility
Functions analysis
Deployment architectures
SDN (OF) realization
14
Conclusion and Outlook
Study goals?
• EPC analysis: derive S-GW and P-GW functions
• SDN capabilities to achieve the EPC functionalities
• Alternative solutions to enhance OF network elements:
a) Controller-based processing
b) Middlebox-based processing
c) NE+ with HW customized functions
d) NE+ with a programmable SW extension
• Deployment possibilities of the EPC nodes and functionalities
Four alternative deployment architectures, between cloud and transport network
Each architecture has its own advantages and limitations
15
S-/P-GWcost
end-to-end delay
data overhead
Signaling
Management
Logic
KPI value
Filterin
g
ChargingGTP/
U-Plane Rules/
Fabric
no functions at cloud
all functions at cloud
Outlook
• Performance evaluation and trade-offs
• Exchanged data overhead
• Observed additional delays
• Cost evaluation
Optimal functions’ splitting solution
considering all given parameters
16
Thank you for your attention
Questions?
17