Software Defined Networking
COMS 6998-10, Fall 2014
Instructor: Li Erran Li
(lierranli@cs.columbia.edu)
http://www.cs.columbia.edu/~lierranli/coms
6998-10SDNFall2014/
11/21/2014: SDN Wireless Networks
Outline
• Review of SDN Security
• SDN Wireless Networks
– Motivation
– Data Plane Abstraction:
• OpenRadio
• PRAN
– Control Plane Architecture
• Radio Access Networks: SoftRAN
• Core Networks: SoftCell
• Cellular WAN: SoftMoW
11/21/14
Software Defined Networking (COMS 6998-10)
2
Review of Previous Lecture: Defense
Against Control Plane Attacks
• Security extension to the
OpenFlow data plane
Control Plane
– Connection migration
• To address scalability
issue
– Actuating trigger
• To address responsiveness
issue
11/21/14
Control Plane Interface
Connection
Migration
Actuating
Trigger
Avant-Guard
Flow
Table
Lookup
Packet
Processing
Flow Table (TCAM and SRAM)
Data Plane
Software Defined Networking (COMS 6998-10) Source: S. Shin, et al.
3
Review of Previous Lecture: Defense
Against Control Plane Attacks (Cont’d)
Connection Migration – Packet Diagram
Control Plane
(4) (5)
Report stage
(9) (10)
Report stage
Classification stage
(1) TCP SYN
(6) TCP SYN
(2) TCP SYN/ACK
(7) TCP SYN/ACK
(3) TCP ACK
A
Migration stage
Relay stage
A-1: A --> B: Migrate
A-2: A --> B: Relay
(8) TCP ACK
Relay stage
B
(12) TCP ACK
TCP Data
(11) TCP ACK
TCP Data
Data Plane
11/21/14
Software Defined Networking (COMS 6998-10)
Source: S. Shin, et al.
4
Review of Previous Lecture: Controller
Security Framework (Cont’d)
11/21/14
Software Defined Networking (COMS 6998-10)
Source: G. Gu, et al, Texas A&M &SRI
5
Review of Previous Lecture: Controller
Security Framework (Cont’d)
event
FRESCO Modular Design
parameter
input
output
action
Module
k
e
y
values
F-DB instance
11/17/14
Software Defined Networking (COMS 6998-10)
Source: G. Gu, et al, Texas A&M &SRI
6
Review of Previous Lecture: Controller Security
Framework (Cont’d)
Native C
Security Apps
PY OF
Apps
Actuator
Python SWIG
OF Apps
Separate
Process
OF IPC Proxy
Directive Translator
IPC Interface
Aggregate Flow Table
FT_Send_OpenFlow_Command
Operator Rules
Role-based Source Auth
State Table Manager
SECURITY Rules
Conflict Analyzer
OF App Rules
OF Mod Commands
Add
(conflict enforced)
Modify (conflict enforced)
Delete (priority enforced)
Switch Callback Tracking
FortNOX
Software Defined Networking (COMS 6998-10)
Source: G. Gu, et al, Texas A&M &SRI
7
Outline
• Review of SDN Security
• SDN Wireless Networks
– Motivation
– Data Plane Abstraction:
• OpenRadio
• PRAN
– Control Plane Architecture
• Radio Access Networks: SoftRAN
• Core Networks: SoftCell
• Cellular WAN: SoftMoW
11/21/14
Software Defined Networking (COMS 6998-10)
8
Wireless Data Growth
Exabyte
• Exponential traffic
growth
11.2
12
Annual Growth 83%
10
7.4
8
6
4.7
4
2
2.8
0.5 0.9
0.0 0.0 0.1 0.2
1.6
Question: How to
substantially improve
wireless capacity?
11/21/14
2017
2016
2015
2014
2013
2012
2011
2010
2009
2008
2007
0
Source: CISCO Visual Networking Index (VNI)
Global Mobil Data Traffic Forecast 2011 to
2016
Software Defined Networking (COMS 6998-10)
9
Outline
• Review of SDN Security
• SDN Wireless Networks
– Motivation
– Data Plane Abstraction:
• OpenRadio
• PRAN
– Control Plane Architecture
• Radio Access Networks: SoftRAN
• Core Networks: SoftCell
• Cellular WAN: SoftMoW
11/21/14
Software Defined Networking (COMS 6998-10)
10
OpenRadio: Access Dataplane
OpenRadio APs built with
merchant DSP & ARM silicon
– Single platform capable of
LTE, 3G, WiMax, WiFi
– OpenFlow for Layer 3
– Inexpensive ($300-500)
Forwarding
Dataplane
Control
CPU
Baseband &
Layer 2 DSP
Exposes a match/action interface to program how a flow
is forwarded, scheduled & encodedRF
RF
RF
11/21/14
Software Defined Networking (COMS 6998-10)
Source: Katti, Stanford
11
Design goals and Challenges
Programmable wireless dataplane using off-theshelf components
– At least 40MHz OFDM-complexity performance
• More than 200 GLOPS computation
• Strict processing deadlines, eg. 25us ACK in WiFi
– Modularity to provide ease of programmability
• Only modify affected components, reuse the rest
• Hide hardware details and stitching of modules
11/21/14
Software Defined Networking (COMS 6998-10)
Source: Katti, Stanford
12
12
Wireless Basebands
OFDM Demod
OFDM Demod
OFDM Demod
Demap
(BPSK)
Demap
(BPSK)
Demap
(64QAM)
Deinterleave
(WiFi)
Deinterleave
Deinterleave
Viterbi Decode
Descramble
CRC Check
Hdr Parse
Decode
(1/2)
Demap
(BPSK)
Decode
(3/4)
Decode
(1/2)
Descramble
11/21/14
Deinterleave
(UEP)
Decode
(3/4)
Descramble
Descramble
CRC Check
CRC Check
Hdr Parse
Hdr Parse
WiFi 6mbps
Demap
(64QAM)
WiFi 6, 54mbps
Hdr Parse
WiFi 6, 18mbps and UEP
Software Defined Networking (COMS 6998-10)
Source: Katti, Stanford
13
13
Modular declarative interface
Composing ACTIONS
J
Deinterleave
Hdr Parse
(UEP)
D Deinterleave
I
CRC Check
(WiFi)
C Demap
H
Descramble
(64QAM)
G Decode
Demap
(BPSK)
(3/4)
F Decode
OFDM
Demod
(1/2)
E
B
A
Blocks
A
A
B
C
F
G
H
H
H
H
I
I
I
J
J
D
B
C
D
H
54M
J
J
I
F
G
Data
flow
H
I
J
UEP
Actions: DAGs of blocks
11/21/14
B
E
G
6M
A
A
D
F
A
F
C
D
Inserting RULES
6M
J
6M, 54M
Rules: Branching logic
Software Defined Networking (COMS 6998-10)
Control
flow
Source: Katti, Stanford
14
State machines and deadlines
• Rules and actions encode the protocol state machine
– Rules define state transitions
– Each state has an associated action
• Deadlines are expressed on state sequences
Start
decoding
B
A
Finish
decoding
F
H
D
I
G
C
11/21/14
deadline
Software Defined Networking (COMS 6998-10)
J
Source: Katti, Stanford
15
15
Design principle I
Judiciously scoping flexibility
• Provide just enough flexibility
• Keep blocks coarse
• Higher level of abstraction
• High performance through
hardware acceleration
– Viterbi co-processor
– FFT co-processor
• Off-the-shelf heterogeneous
multicore DSPs
– TI, CEVA, Freescale etc.
11/21/14
Software Defined Networking (COMS 6998-10)
Algorithm
WiFi
LTE
3G
DVB-T
FIR / IIR
√
√
√
√
Correlation
√
√
√
√
Spreading
√
FFT
√
√
Channel
Estimation
√
√
√
√
QAM
Mapping
√
√
√
√
Interleaving
√
√
√
√
Convolution
Coding
√
√
√
√
√
√
Turbo Coding
√
Randomization
√
√
√
CRC
√
√
√
√
16
A
Design principle II
Processing-Decision separation
B
D
• Logic pulled out to decision plane
• Blocks and actions are branch-free
F G
H
I
J
– Deterministic execution times
– Efficient pipelining, algorithmic
scheduling
– Hardware is abstracted out
Regular compilation
OpenRadio scheduling
Instructions
Atomic processing blocks
Heterogeneous functional units
Heterogeneous cores
Known cycle counts
Predictable cycle counts
Argument data dependency
FIFO queue data dependency
C
6M, 54M
A
B
C
D
60x
E
F
17
Prototype
I/Q baseband
samples
RF signal
(Analog)
(Digital)
Baseband-processor unit (BBU)
Layer 1 & 2
Radio front end (RFE)
Antenna chain(AX)
Layer 0 & 1
Layer 0
• COTS TI KeyStone multicore DSP platform
(EVM6618, two chips with 4 cores each at 1.2GHz,
configurable hardware accelerators for FFT, Viterbi, Turbo)
• Prototype can process 40MHz, 108Mbps 802.11g
on one chip using 3 of 4 cores
11/21/14
18
Software Defined Networking (COMS 6998-10)
Source: Katti, Stanford
18
OpenRadio: Current Status
• OpenRadio APs with full WiFi/LTE software on
TI C66x DSP silicon
• OpenRadio commodity WiFi APs with a
firmware upgrade
• Network OS under development
11/21/14
Software Defined Networking (COMS 6998-10)
Source: Katti, Stanford
19
Software architecture
BBU
RFE
(Digital)
protocol state machine, flowgraph
composition, block configurations,
knowledge plane, RFE control logic
OR Wireless Processing Plane
i
n
11/21/14
(Analog)
OR Wireless Decision Plane
monitor
&
co
ntr
ol
data
AX
data
o
u
t
deterministic signal processing blocks,
header parsing, channel resource
scheduling, multicore fifo queues,
sample I/O blocks
OR Runtime System
compute resource
scheduling,
deterministic execution
ensuring protocol
deadlines are met
Bare-metal with drivers
20
Outline
• Review of SDN Security
• SDN Wireless Networks
– Motivation
– Data Plane Abstraction:
• OpenRadio
• PRAN
– Control Plane Architecture
• Radio Access Networks: SoftRAN
• Core Networks: SoftCell
• Cellular WAN: SoftMoW
11/21/14
Software Defined Networking (COMS 6998-10)
21
PRAN Programmability
• Hardware/software radio
Data Flow
Scheduler
Base Station Information Base
– Not easy to program
Control Plane
Control Flow
• Programmable Radio
State Flow
Data Plane
– Flexible datapath, interfaces
Turbo
Coding
Scrambling
Scheduler
Scheduler
Modulation
Reed-Muller
Coding
Down Link
Transport
Block
I&Q
Samples
Up Link
Turbo
Decoding
Scheduler
Channel
Estimation
Demodulation
Scheduler
Reed-Muller
Decoding
11/21/14
Software Defined Networking (COMS 6998-10)
22
RRH
Fiber
Radio Plane
Operator1
Operator2
L1/L2
L1/L2
L1/L2
Scheduler
Scheduler
Scheduler
Data Plane
Control Plane
RAN Scheduler
RAN Scheduler
Management
Plane
Resource Manager
Cloud
Infrastructure
server
Gateway
11/21/14
Internet
Software Defined Networking (COMS 6998-10)
23
Summary
Provides programmatic interfaces to monitor and
program wireless networks
– High performance substrate using merchant silicon
11/21/14
Software Defined Networking (COMS 6998-10)
24
Outline
• Review of SDN Security
• SDN Wireless Networks
– Motivation
– Data Plane Abstraction:
• OpenRadio
• PRAN
– Control Plane Architecture
• Radio Access Networks: SoftRAN
• Core Networks: SoftCell
• Cellular WAN: SoftMoW
11/21/14
Software Defined Networking (COMS 6998-10)
25
Carrier’s Dilemma
Exponential Traffic Growth
8
Exabyte
11.2
12
Annual Growth 83%
10
Shannon
6
Shannon (3dB)
4
6
4.7
2.8
0.5 0.9
0.0 0.0 0.1 0.2
2
1.6
1
2017
2016
2015
2014
2013
2012
2011
2010
2009
2008
0
2007
4G
3
0
-15
-12.5
-10
-5
-2.5
0
2.5
5
7.5
10
12.5
15
17.5
20
4
•
7
5
7.4
8
2
Limited Capacity Gain
Poor wireless connectivity if left unaddressed
11/21/14
Software Defined Networking (COMS 6998-10)
26
LTE Radio Access Networks
• Goal: high capacity wide-area coverage
– Dense deployment of small cells
Base Station (BS)
Serving Gateway
Packet Data
Network Gateway
User Equipment (UE)
Serving Gateway
access
11/21/14
Internet
core
Software Defined Networking (COMS 6998-10)
27
Dense and Chaotic
Deployments
• Dense: high SNR per user leads to higher
capacity
o
Small cells, femto cells, repeaters, etc
11/21/14
Software Defined Networking (COMS 6998-10)
28
Problems
•
Current LTE distributed control plane is ill-suited
o Hard to manage inter-cell interference
•
o Hard to optimize for variable load of cells
Dense deployment is costly
o Need to share cost among operators
o Maintain direct control of radio resources
o Lacking in current 3gpp RAN sharing standards
29
SoftRAN: Big Base Station
Abstraction
Big Base Station
Radio Element 1
time
controller
frequency
Radio Element 2
time
time
Radio Element 3
time
frequency
frequency
11/21/14
Software Defined Networking (COMS 6998-10)
30
Radio Resource Allocation
3D Resource Grid
time
Flows
11/21/14
Software Defined Networking (COMS 6998-10)
31
31
SoftRAN: SDN Approach to RAN
Coordination :
X2 Interface
Control Algo
Control Algo
PHY & MAC
PHY & MAC
Control Algo
PHY & MAC
BS1
BS3
Control Algo
PHY & MAC
BS2
11/21/14
Control Algo
BS5
PHY & MAC
BS4
Software Defined Networking (COMS 6998-10)
32
SoftRAN: SDN Approach to RAN
Control Algo
Operator Inputs
Network OS
RadioVisor
PHY & MAC
PHY & MAC
PHY & MAC
RE3
RE1
RE5
PHY & MAC
Radio Element
(RE)
RE2
PHY & MAC
RE4
33
SoftRAN Architecture Summary
CONTROLLER
RAN Information Base
Periodic Updates
Controller
API
•
•
•
RADIO ELEMENTS
Interference
Map
Bytes
Rate
Queue
Size
Flow
Records
Network
Operator
Inputs
QoS
Constraints
Radio
Element
API
11/21/14
Radio Element
3D Resource Grid
POWER
FLOW
Radio Resource
Management
Algorithm
Frequency
34
34
SoftRAN Architecture: Updates
• Radio element -> controller (updates)
– Flow information (downlink and uplink)
– Channel states (observed by clients)
• Network operator -> controller (inputs)
– QoS requirements
– Flow preferences
11/21/14
Software Defined Networking (COMS 6998-10)
35
35
SoftRAN Architecture: Controller
Design
• RAN information base (RIB)
– Update and maintain global network view
• Interference map
• Flow records
• Radio resource management
– Given global network view: maximize global
utility
– Determine RRM at each radio element
11/21/14
Software Defined Networking (COMS 6998-10)
36
36
SoftRAN Architecture: Radio Element API
• Controller -> radio element
– Handovers to be performed
– RF configuration per resource block
• Power allocation and flow allocation
– Relevant information about neighboring radio
elements
• Transmit Power being used
11/21/14
Software Defined Networking (COMS 6998-10)
37
37
Refactoring Control Plane
• Controller responsibilities:
- Decisions influencing global network state
• Load balancing
• Interference management
• Radio element responsibilities:
- Decisions based on frequently varying local
network state
• Flow allocation based on channel states
11/21/14
Software Defined Networking (COMS 6998-10)
38
38
SoftRAN Advantages
• Logically centralized control plane:
– Global view on interference and load
• Easier coordination of radio resource management
• Efficient use of wireless resources
– Plug-and-play control algorithms
• Simplified network management
– Smoother handovers
• Better user-experience
11/21/14
Software Defined Networking (COMS 6998-10)
39
39
SoftRAN: Evolving the RAN
• Switching off radio elements based on load
– Energy savings
• Dynamically splitting the network into BigBSs
– Handover radio elements between Big-BSs
11/21/14
Software Defined Networking (COMS 6998-10)
40
40
RadioVisor Design
•
Slice manager
o
Traffic to
Slice
Mapping
3D Resource
Grid
Allocation &
Isolation
RadioVisor
Slice
Manager
•
•
Traffic to slice mapping at
RadioVisor and radio
elements
3D resource grid allocation
and isolation
o
11/21/14
Slice configuration, creation,
modification, deletion and multislice operations
Considers traffic demand,
interference graph and policy
Software Defined Networking (COMS 6998-10)
41
Slice Manager
•
•
•
Slice definition
o Predicates on operator, device, subscriber, app
attributes
o
A slice can be all M2M traffic of operator 1
Slice configuration at data plane and control plane
o PHY and scheduler: narrow band PHY for M2M
slice
o Interference management algorithm
Slice algebra to support flexible slice operations
o Slice merge, split, (un)nest, duplicate
11/21/14
Software Defined Networking (COMS 6998-10)
42
•
•
Slices present resource
demands every time window
Max min fair allocation
Example
Radio
o Red slice entitles 2/3 and Element 1
demands 2/3 RE1 only
o Blue slice entitles 1/3 and
demand 1/3 RE2 and 1
RE3
11/21/14
Software Defined Networking (COMS 6998-10)
Interference Edge
Radio
Radio
Element 2 Element 3
Frequency
•
Resource Grid Allocation and
Isolation
43
Summary
•
•
•
Dense deployment calls for central control of
radio resources
Deployment costs motivate RAN Sharing
We present the design of RadioVisor
o Enables direct control of per slice radio
resources
o Configures per slice PHY and MAC, and
interference management algorithm
o Supports flexible slice definitions and
operations
11/21/14
Software Defined Networking (COMS 6998-10)
44
Outline
• Review of SDN Security
• SDN Wireless Networks
– Motivation
– Data Plane Abstraction:
• OpenRadio
• PRAN
– Control Plane Architecture
• Radio Access Networks: SoftRAN
• Core Networks: SoftCell
• Cellular WAN: SoftMoW
11/21/14
Software Defined Networking (COMS 6998-10)
45
LTE Cellular Network Architecture
Base Station (BS)
Serving Gateway
Packet Data
Network Gateway
Serving Gateway
Internet
User Equipment (UE)
access
11/21/14
core
Software Defined Networking (COMS 6998-10)
46
Cellular core networks are not flexible
• Most functionalities are implemented at
Packet Data Network Gateway
Packet Data
Network Gateway
– Content filtering, application identification,
stateful firewall, lawful intercept, …
• This is not flexible
Combine functionality from different vendors
Easy to add new functionality
Only expand capacity for bottlenecked functionality
11/21/14
Software Defined Networking (COMS 6998-10)
47
SoftCell Overview
Simple hardware
+ SoftCell software
Controller
Interne
t
11/21/14
Software Defined Networking (COMS 6998-10)
48
SoftCell Design Goal
Fine-grained service policy for diverse app needs
»
»
Video transcoder, content filtering, firewall
M2M services: fleet tracking, low latency medical
device updates
with diverse needs!
11/21/14
Software Defined Networking (COMS 699810)
49
Characteristics of Cellular Core
Networks
1. “North south” traffic pattern
2. Asymmetric edge
3. Traffic initiated from low-bandwidth access
edge
Gateway Edge
Internet
~1 million Users
~10 million flows
~400 Gbps – 2 Tbps
Access
Edge
11/21/14
~1K Users
~10K flows
~1 – 10 Gbps
Software Defined Networking (COMS 6998-10)
50
Challenge: Scalability
Packet classification: decide which service policy
to be applied to a flow
» How to classify millions of flows per second?
Traffic steering: generate switch rules to implement
policy paths, e.g. traversing a sequence of
middleboxes
» How to implement million of paths?
• Limited switch flow tables: ~1K – 4K TCAM, ~16K – 64K
L2/Ethernet
Network dynamics: setup policy paths for new
users and new flow?
Software Defined
Networking (COMS
6998-10)
11/21/14to handle million
» How
of control
plane
events per
51
SoftCell Design
Controller
1. Scalable system design
»
»
Classifying flows at access
edge
Offloading controller tasks
to switch local agent
2. Intelligent algorithms
»
»
LA
LA
Gateway Edge
LA
Enforcing policy
LA
consistency under mobility
Multi-dimension
Access
Edge
aggregation to reduce
~1K Users
~10K flows
switch rule entries
~1 million Users
~10 million flows
~up to 2 Tbps
~1 – 10 Gbps
11/21/14
Software Defined Networking (COMS 6998-10)
52
Multi-Dimensional Aggregation
Use multi-dimensional tags rather than flat tags
Policy Tag
BS ID
User ID
Aggregate
Aggregate
Aggregate
flows that
flows going
flows going
share a
to the same to the same
common
Users.
(group of)
policy (even
base
across Users
stations
Exploit
andlocality
BSs)in network topology and traffic pattern
Selectively match on one or multiple dimensions
» Supported by the multiple tables in today’s switch chipset
11/21/14
Software Defined Networking (COMS 6998-10)
53
Location-Based Hierarchical IP
Address
BS 1
BS 2
BS 3
BS 4
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Software Defined Networking (COMS 6998-10)
54
Location-Based Hierarchical IP
Address
BS 1
10.0.0.0/16
BS ID: an IP prefix assigned
to each base station
BS ID
BS 2
BS 3
192.168.0.5
10.1.0.7
UE ID
10.2.0.0/16
• UE ID: an IP suffix unique
under the BS ID
BS 4
11/21/14
10.1.0.0/16
10.3.0.0/16
Software Defined Networking (COMS 6998-10)
55
Route to different BSs with BS
IDprefix matching
Forward to base station with
Can aggregate nearby BS IDs
BS 1
10.0.0.0/16
SW 1
BS 2
10.1.0.0/16
11/21/14
SW 2
SW 3
SW 4
Match
Action
10.0.0.0/16
Forward to BS 1
10.1.0.0/16
Forward to BS 2
Match
Action
10.0.0.0/15
Forward to Switch 3
Software Defined Networking (COMS 6998-10)
56
MB load balancing with policy tag and
BS ID
BS 1
10.0.0.0/16
BS 2
10.1.0.0/16
SW 1
SW 2
SW 3
BS 3
10.2.0.0/16
SW 4
SW 5
Transcoder 1
BS 4
10.3.0.0/16
Transcoder 2
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57
MB load balancing with policy tag and
BS Match
ID
BS 1
Action
10.0.0.0/16
BS 2
10.1.0.0/16
tag1, 10.0.0.0/15
SW 1
10.2.0.0/15
SW 2
Forward to Transcoder 1
Forward to Switch 5
SW 3
BS 3
10.2.0.0/16
SW 4
SW 5
BS 4
10.3.0.0/16
Transcoder 2
11/21/14
Transcoder 1
Match
Action
tag1, 10.2.0.0/15
Forward to Transcoder 2
Software Defined Networking (COMS 6998-10)
58
Policy Consistency
UE Mobility: frequent, unplanned
Policy consistency:
» Ongoing flows traverse the same sequence of
middlebox instances, even in the presence of UE
mobility
» Crucial for stateful middleboxes, e.g., stateful firewall
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59
Policy Consistency
An ongoing flow traverses stateful Firewall 1 before handoff
» Use 10.0.0.7 (old IP under BS1), go via the old path
New Flow can go via stateful Firewall 2
Old Path
» Use 10.1.0.11 (new IP under BS2), go via the new path
BS 1: 10.0.0.0/16
Firewall 1
New Path
10.0.0.7
Old flow
Handoff
192.168.0.5
BS 2: 10.1.0.0/16
Old Flow
10.1.0.11
10.0.0.7
New Flow
192.168.0.5
11/21/14
New Flow
10.1.0.11
Firewall 2
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60
Multi-Dimensional Identifier
Encoding
Encode multi-dimensional identifiers to source IP and
source port
Policy Tag
UE ID
BS ID
Encode
Src IP
Src Port
BS ID
UE ID
Tag
Flow ID
Return traffic from the Internet:
» Identifiers are implicitly piggybacked in destination IP and
destination port
Commodity
chipsets (e.g.,
Broadcom) can wildcard on
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these bits
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Scalable Data Plane Summary
Packet classification
based on service policy
Traffic steering based on
traffic management policy
Encoding results to
packet headers
Selectively multidimensional aggregation
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Simple forwarding
based on multidimensional tags
Steering Fabric
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Control Plane Load
Packet classification
Handle every flow
Frequent switch update
Multi-dimensional aggregation
Handle every policy path
Infrequent switch update
Internet
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Software Defined Networking (COMS 6998-10)
Summary
• SoftCell uses commodity switches and middelboxes to
build flexible and cost-effective cellular core networks
• SoftCell achieves scalability with
Data Plane
Asymmetric Edge Design
Multi-dimensional Aggregation
Control Plane
Hierarchical Controller Design
• Exploit multi-stage tables in modern switches
– Reduce m×n rules to m+n rules
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Outline
• Review of SDN Security
• SDN Wireless Networks
– Motivation
– Data Plane Abstraction:
• OpenRadio
• PRAN
– Control Plane Architecture
• Radio Access Networks: SoftRAN
• Core Networks: SoftCell
• Cellular WAN: SoftMoW
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LTE Cellular Network Architecture
Base Station (BS)
Serving Gateway
Packet Data
Network Gateway
Serving Gateway
Internet
User Equipment (UE)
access
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core
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Current Mobile WANs
• Organized into rigid and very large regions
• Minimal interactions among regions
• Leads to poor user experience and poor
resource utilization
Two Regions
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SoftMoW Solution
• Hierarchically builds up a network-wide control plane
– Lies in the family of recursive SDN designs (e.g. XBAR,
ONS’13)
• In each level, abstracts both control and data planes
and exposes a set of “dynamically-defined” logical
components to the control plane of the level above.
– Virtual Base stations (VBS), Gigantic Switches (GS),
and Virtual Middleboxes (VMB)
Latency
Matrix
Union of
Coverage
Sum of
capacities
VBS
GS
VMB
Core Net
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RadioAccess
Network
Software Defined Networking (COMS 6998-10)
Policy
68
SoftMoW Solution
• New Dynamic Feature: In each level, the
control logic can modify its logical
components for optimization purposes
– E.g., merge/spilt and move operations
GSW2
GSW1
VBS1
GSW1
VBS1
VBS2
GSW1
GSW3
Merge/Split
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GSW2
VBS2
VBS3
GSW2
Move and Split
Software Defined Networking (COMS 6998-10)
VBS3
69
First Level-SoftMoW Architecture
• Replace inflexible and expensive hardware devices (i.e.,
PGW, SGW) with SDN switches
• Perform distributed policy enforcement using middle-box
instances
• Partition the network into independent and dynamic logical
regions
• A child controller manages the data plane of each regions
Events GS Rules &
Actions
Agent A
Bootstrapping phase:
based on location
and processing
capabilities of child
controllers
Local
Apps
Child A
NIB
E2
Boundary
M
1
Region A
E1
M
M
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E3
M
2
4
BS1
M
3
5
M
6
Region B
I1
7
9
BS
E4
M
8
M
M
10
BS
BS2 BS
4 6998-10) 5
Software Defined
Networking
(COMS
3
M
BS6
70
Second Level-SoftMoW Architecture
• A parent runs a global link discovery protocol
– Inter-region links are not detected by BDDP and LLDP
• A parent participates in the inter-domain routing protocol
• A parent builds virtual middlebox chains and egresspoint policies, and dictates to GSs
Events GS Rules &
Actions
Agent A
I-Mobility
Manager
Local
Apps
Middlebox Egress
Optimizer Selection
Child A
NIB
E2
E3
Boundary
M 1
Region A
E1
M 3
M 2
M
4
BS111/21/14
6
Region B
I1
7
M
E4
8
M
GS
Protocol
E1
M
9
5
BS2
BS3
10
M
E2
E3
E4
-----
M M
M M
M
BGP
sessions
Parent
NIB
M
Region
Optimizer
2M M
BS4
BS
BS6
Internal
Software5Defined
Networking (COMS 6998-10)
VBS1
GSA
Border
VBS
1
I1
GSB
2M M
Border Internal
VBS
2 VBS2
71
Controller Architecture
To Parent Controller
SoftMoW Controller
Eastbound API
Operator Applications
RecA
Agent
G-switch
Region Optimization … Mobility
Topology Abstraction
G-BS
Northbound API
Core Services
Path Implementation
Topology Discovery
Southbound API
Routing
NIB
Recursive Link Discovery Protocol
GS1$
(1)$
(C0,$GS1,$p1)$
(C0,$GS1,$p1)$
(GS2,$p4)$
C0$
(C1,$SW2,$p2)$
C2$
C1$
GS2$
(4)$
(C0,$GS1,$p1)$ (3)$
(SW3,$p3)$
(2)$
(C1,$SW2,$p2)$
(C0,$GS1,$p1)$
SW1$
SW2$ Payload$ Stack$
SW3$
SW4$
Path Implementation
• A parent pushes a global label into each traffic group
• Child controllers perform label swapping
o Ingress point: pop the global label and push some local labels for intra-region
paths
GS Rules &
Eventsthe
o Egress point: pop the local labels and push back
global label
Actions
Push W
I-Mobility
Manager
Middlebox
Optimizer
Agent A
Egress
Selection
Region
Optimizer
Parent
NIB
GS
Protocol
E1
E2
E3
2M M
Latency
(P1,E2)=300
Latency
(P1,E4)=100
GSA
Internal
VBS1
Push W
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Border
VBS
1
I1
E2
GSB
E3
Boundary
M 1
Region A
E1
E4
M M
M M
Child A
NIB
Pop W2
Push W
-----
Web
Voice
BGP
sessions
Local
Apps
Pop W1
M 2
Region B
I1
M 3
M
6
7
E4
M
8
M
2M M
GS
Rules
Border Internal
VBS
VBS2
2
M
4
BS1
Pop W
Push W1
M
5
BS2
Pop W
9
BS3
BS4
M
M
10
BS5
BS6
Push W2
74
Software Defined Networking (COMS 6998-10)
Time-of-day Handover Optimization
Q: How can an operator reduce inter-region
handovers in peak
E
A
M
GSA
M M
VBS1
VBS1
VBS2
Border
VBS2
Abstraction update
coordination
Child A
E2
Parent
E3
E4
Child B
E3
Boundary
M
M 1
Region A
E1
E2
Internal
VBS2
VBS2
Handover graph
E1
3M M
GSB
Border
VBS
1
Min Cut
300 Border 1000 Border 2000 Internal
Internal
E4
M 2M
E3
E2
1
hours?
GS
M 2
Region B
I1
M 3
6
7
M
8
M
M M
M M
2M M
GSA
I1
GSB
2M M
GS Rule:
Move Border VBS1
M
4
M
BS2
BS1
Internal
VBS1
Border
VBS1
Border Internal
VBS2 VBS
2
New
Border
9
5
BS3
Old
Border
BS4
M
M
10
BS5
BS6
75
Summary
SoftMoW:
• Brings both simplicity and scalability to the
control plane of very large cellular networks
– decouples control and data planes at multiple
levels ( focused only on two levels here)
• Makes the deployment and design of
network-wide applications feasible
– E.g., seamless inter-region mobility, time-of-day
handover optimization, region optimization, and
traffic engineering
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Conclusion and Future Work
• Software defined cellular networks address
fundamental limitations of current cellular
architecture
– Control plane abstractions: 3D resource grid, big
base station, virtual data plane
– Intelligent algorithms in the control plane to
achieve global objects: interference
management, traffic engineering
• Future work on software defined cellular
networks
– Security
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Software Defined Networking (COMS 6998-10)
Questions?
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