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1 Radisys Corporation Confidential
Welcome!
April 12
Deploying LTE Small Cells: Interference
Mitigation Solutions
May 17
Building EPC Systems
June 14
The LTE Service Layer
July 12
End-to-End QoS in LTE
Real Implementation Challenges
of LTE Network Equipment:
Exploring the Trade-offs and
Solutions
To view past webinars:
http://www.radisys.com/recent-webinars/
2 Radisys Corporation Confidential
End-to-End QoS in LTE Delivering the Appropriate Customer Experience
Speakers:
Larry Greenstein – Sr. Product Line Manager
Dikshit Sawhney – Software Architect
James Radley – Sr. Architect
July 12, 2012
3 Radisys Corporation Confidential
Today’s Agenda
Market Dynamics
LTE QoS Fundamentals
LTE QoS Methods and Mechanisms
Policy Enforcement
Conclusion
Q&A / Wrap-up
4 Radisys Corporation Confidential
End-to-End LTE Infrastructure From Radio Access to Media Processing
Evolved Packet Core Policy Control Radio Access Network IMS
Application
Server Media
Resource
Function
IP
Multimedia
Subsystem
Internet
Policy &
Charging
Routing
Function
Policy &
Charging
Enforcement
Function
Mobility
Management
Entity
LTE Security
Gateway
Serving
Gateway
Packet
Gateway
eNodeB
User
Equipment
Macro Small Cells
60+ Customer Wins
Audio Video Conf
~65% Market Share
10G 40G ATCA
~40% ATCA Market Share
Dumb Smart Pipes
Traffic Management
Home eNodeB
User
Equipment
5 Radisys Corporation Confidential
Usage Up, Revenue Down QoS to the Rescue
Capacity Mind The Gap
Text
Traffic Doubling every 12 months
Video = Operators’ Albatross
Must Increase ARPU
Must Lower Cost per Bit
Source: Cisco VNI Source: Heavy Reading
Revenues
Traffic
Revenues &
Traffic Gap
Widening
Revenue vs. Traffic Growth
Voice Era
Data Era
6 Radisys Corporation Confidential
Today’s Agenda
Market Dynamics
LTE QoS Fundamentals
LTE QoS Methods and Mechanisms
Policy Enforcement
Conclusion
Q&A / Wrap-up
7 Radisys Corporation Confidential
LTE QoS: Fundamental Need
Why QoS?
• Finite network resources
– Radio spectrum limited
– Backhaul bandwidth limited
– Network congestion has to be managed
• Users (applications) need a variety of services
– Guaranteed bit rate (voice)
– High speed throughput (video)
– Priority service (emergency call)
8 Radisys Corporation Confidential
Policy Control and Charging (PCC)
Policy Management
• Operator control over network usage
• Control the level of service provided and charge accordingly
– Superior performance for the customers that pay for it
– Enforce limits or restrictions based on customer subscription
– Dynamic service level adjustment enhances QoE
– Offer attractive options to gain market share
– Restrict content based on subscription or local laws
9 Radisys Corporation Confidential
Where QoS Happens in the Network
Policy &
Charging
Rules
Function
Policy & Charging
Enforcement Function
Mobility
Management
Entity
Serving
Gateway
PDN
Gateway
eNodeB
Internet
Web
Voice
UE
Radio
Bearer
S1
Bearer
S5
Bearer
Home
Subscriber
Server
Service
Data Flows
Packet
Filters
AF
Application
Function
IMS
Network
10 Radisys Corporation Confidential
Poll Question 1
The top QoS concern of operators and equipment
manufacturers is:
A. Adding value and monetizing it (increase revenue)
B. Efficient use of network resources (reduce cost)
C. Ensuring customer satisfaction
D. Compliance with regulations
11 Radisys Corporation Confidential
Today’s Agenda
Market Dynamics
LTE QoS Fundamentals
LTE QoS Methods and Mechanisms
Policy Enforcement
Conclusion
Q&A / Wrap-up
12 Radisys Corporation Confidential
Agenda – QoS Specifics
QoS Functions in Control & User Plane
Policy & Charging Control Architecture
EPS Bearers and Service Data Flows
QoS Attributes
Example PCC Call Flow
13 Radisys Corporation Confidential
QoS Functions
Control Plane
• Admission control maintains information about all available
resources of a network entity and takes decision to allow a
new session or not based on the current resource usage.
• Subscription Control checks whether or not a user is entitled
to use the requested service with the specified QoS attributes
• Service Management coordinates the functions of the control
plane entities during setup, modification and deletion of the
EPS bearers
• Translation function converts between the EPC QoS
parameters the various protocols for service control of
interfacing external networks e.g., UMTS to IP QoS parameters
mapping
14 Radisys Corporation Confidential
QoS Functions
User Plane
• Mapping function provides each data unit with the specific
marking required to receive the intended QoS at the transfer
by a bearer service, e.g., DSCP marking at the PDN-GW
• Classification function assigns data units to the established
services of a user according to the related QoS attributes if
the user has multiple bearer services established
• Resource Manager distributes the available resources
between all services sharing the same resource based on the
QoS, e.g., scheduling, bandwidth management, and power
control for the radio bearers
• Traffic Shaping provides conformance between the
negotiated QoS for a service and the arriving data traffic
15 Radisys Corporation Confidential
TE MT RAN CN EDGE Gateway Ext.
Netwk.
QoS Functions in different Network Elements
RAN Access Network
Service BB network service
Local BS Resource
Manager
Cond.
Class.
Resource
Manager
Cond.
Resource
Manager
Mapping
Resource
Manager
Mapping
Resource
Manager
Mapping
External BS
Cond.
Class.
RAN phys. BS
16 Radisys Corporation Confidential
Policy and Charging Control (PCC) Architecture
Policy and Charging Rules
Function (PCRF)
Subscription
Profile
Repository
(SPR)
AF
Offline
Charging
System
(OFCS)
BBERF
Gateway
PCEF
Online
Charging
System (OCS)
Sp Rx
Gxx Gx
Gy
Gz
17 Radisys Corporation Confidential
PCC Network Elements
PCRF (Policy & Charging Rules Function)
• PCRF is the central node in the policy and charging control architecture; it keeps a DB of PCC rules in SPR and supports flow-based charging and policy (QoS)
• Interworks with other network elements via the Diameter protocol
SPR (Subscription Profiles Repository)
• DB of PCC rules; can be co-located with HSS or PCRF
• A PCC rule consists of traffic filters to map Service Data Flows (SDF) to EPS Bearers, QoS and charging related parameters
PCEF (Policy & Charging Enforcement Function)
• The enforcement part of the policy architecture
• Main functions include DPI, traffic shaping, etc.
• Typically co-located with a PDN-GW
BBERF (Bearer Binding and Event Reporting Function) • Bearer Binding and Event Reporting Function
• Use PCC rules to map SDFs to EPS bearers; logical function of PDN-GW
18 Radisys Corporation Confidential
Relationship between SDF Flows and EPS Bearers
QoS is defined on a per EPS Bearer basis
• An EPS bearer is an end-to-end connection between the
service user and PDN-GW. It consists of EPC Bearer, S1
Bearer and Radio Bearer
• Service data flows sharing the same QoS/IP address use the
same EPS bearer. Examples of SDFs include FTP, HTTP,
VoIP IMS traffic etc.
• Traffic filters at UE and PDN-GW determine which traffic flow
gets mapped to which EPS Bearer
19 Radisys Corporation Confidential
EPS Bearers
GBR vs. Non-GBR Bearers
• GBR require resources to be reserved in every node in the
EPS through which data packet traverses; requires efficient
admission control methods
• Non-GBR specifies best-effort service – useful for
background, interactive traffic classes such as email, web
browsing, file download, etc.
Dedicated vs. Default Bearers
• Default bearer (one per UE IP) setup on Attach provides
basic connectivity – best effort QoS, non-GBR
• One or more Dedicated bearers setup for specific QoS
requirements – can be GBR or non-GBR
20 Radisys Corporation Confidential
QoS Attributes
Maximum bit rate (MBR, AMBR)
• Maximum allowable bit rate for a GBR bearer or Aggregate
Maximum bit rate for all non-GBR bearers combined
• AMBR defined on per APN and per subscriber basis
Guaranteed bit rate (GBR)
• Guaranteed by the network via Admission Control
• Can’t exceed MBR in Release 8
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QoS Attributes, continued
QoS Class Identifier (QCI)
• Defines packet forwarding treatment at each node, e.g.,
queuing thresholds, scheduling weight, admission control
priority, etc.
• Nine standardized QCI values with different characteristics –
GBR/non-GBR, priority, delay sensitivity, and packet error
loss rate e.g., QCI 1 is defined for a GBR bearer for
conversational or voice traffic
Allocation and Retention Priority (ARP)
• “Allocation” dictates control plane behavior during bearer
setup, modification procedures, etc.
• “Retention” determines relative priority of a bearer over
other bearers in case of congestion
• Fifteen different ARP (priority) levels – 1 being the highest
priority
22 Radisys Corporation Confidential
UE eNodeB MME Serving GW PDN GW PCRF
Call Flow - PCRF Interaction During Dedicated Bearer Setup
(A)
(B)
1. IP-CAN Session Modification
2. Create Bearer Request
11. Create Bearer Response
12. IP-CAN Session Modification
3. Create Bearer Request
4. Bearer Setup Request / Session Management Request
5. RRC Connection Reconfiguration
7. Bearer Setup Response
8. Direct Transfer
6. RRC Connection Reconfiguration Complete
9. Session Management Response
10. Create Bearer Response
23 Radisys Corporation Confidential
Today’s Agenda
Market Dynamics
LTE QoS Fundamentals
LTE QoS Methods and Mechanisms
Policy Enforcement
Conclusion
Q&A / Wrap-up
24 Radisys Corporation Confidential
PCEF and DPI
The Policy & Charging Enforcement Function (PCEF)
cannot rely on coarse-grained assumptions about flow
types
• Subscriber to be identified and associated policy profile retrieved
• DPI of multiple initial packets in every new stream required to
correctly determine service signature
• Fragmented packets may need to be temporarily reassembled for
analysis before forwarding on in original pieces.
Policy engines need to be tailored to the unique
requirements for the confluence or regional usage
patterns and characteristics of installed network
• Enforce only those policies which matter and with no more
precision than necessary
25 Radisys Corporation Confidential
User Specified Profiles
The win-win cost / benefit advantage of user-elected
usage profiles make this a compelling technology
My ideal profile may not be yours, e.g.:
• On-time delivery of VoIP packets above all else
• Anything over VPN should get preference over everything below
• Favor web browsing traffic
– But no need to hurry advertisements
• Don’t prejudice email traffic unless you must
• Feel free to throttle video (I don’t care) – unless I’m on Wi-Fi
• Please block software updates when I am roaming
– Particularly difficult: how does an operator export preference profiles?
26 Radisys Corporation Confidential
Typical Flow Management Architecture
De-tunnel Extract flow ID Flow
Table
Known Flow Apply Rule
Application processing
- Load Balance
- Rate shaping
- Monitoring / Analysis
- Video conversion
- Policy enforcement
Unknown Classification Engine
Stateful, application aware, load balancer is key for traffic steering applications
Stage 1 Stage 2 Stage 3
Stage 4
Stage 5
~ 90% of packets
~ 10% of packets Update flow table
Update flow table
Custom
appln
Low
level
Assign new flow to
appropriate target
resource
Stage 6
27 Radisys Corporation Confidential
Packet Flow Analysis
New packets arriving enable additional detail to be extracted from flow
HTTP GMAIL Metadata
…Username
…Email title
…Content
Apply Rule
Buffered
Packets
e.g. put into correct
priority queue
State Machine API
API Application adds
table entry & rule
Add new entry by default…
…or wait for application
Server Load
…approx 10% packets
User Application
28 Radisys Corporation Confidential
Possible Mapping of LTE QCI: Single Subscriber
QC1
Voice
Flow Shaper
Commit/Excess/Red CIR
Com
mit
WF
Q
QC5
Signaling
Str
ict P
riority
Priority 1
Non
-CIR
WF
Q
Cla
ss S
ha
pe
r
Prio
rity
Ma
pp
er
QC2
Video
Flow Shaper
Commit/Excess/Red
QC3
Video
Flow Shaper
Commit/Excess/Red
QC4
Gaming
Flow Shaper
Commit/Excess/Red
CIR
Excess
WF
Q
QC6
Gaming
QC7 Video
QC8 TCP
Priority 2
Priority 4
Priority 3
<Commit
Green
<Excess
Yellow
>Excess
Red
29 Radisys Corporation Confidential
Example: Traffic Management Assist
NPU mezzanine provides 80Gbps NPU for PP81 to
accelerate blade performance
Broad potential applications
• Load Balancing
• Ingress Traffic Management
• Egress Traffic Management
• IP Defragmentation
• Packet Normalization
• Statistics Acceleration
Efficient Software Interface for low overhead on XLP
30 Radisys Corporation Confidential
Traffic Management Connectivity
RT
M
Broadcom
Trident switch
XLP832
XLP832
TM Mezzanine
PCIe x8 / ILA
4x10G
4x10G
Fab
ric
5 x 40G
(fabric ch0-4)
ICI
4 D
IMM
4 DIMM
120G
Up to 120Gbps
200G Fabric
Up to 5 ports
PCIe x8
8 x10G
PCIe x1
TM Unit
TM connects into main Ethernet switch to allow for flexible packet
routing configurations
TM managed over PCIe by XLP
Buffer
Memory
Stats
Memory
31 Radisys Corporation Confidential
Traffic Management Key Features
Network processors can be used to add a number of
Traffic Management (TM) capabilities to a DPI blade:
• Egress traffic shaping with 256k queues and 5 levels of hierarchy
• Ingress packet filtering and denial-of-service prevention
• Flow-based load balancing across associated processors
• IP Defragmentation and packet reassembly
An NPU is designed to maintain the huge array of per-
Class of Service (CoS) queue counters and timers
required to provided fine-grained scheduling
• Weighted Round Robin (WRR)
• Deficit [Weighted] Round Robin (DRR / DWRR)
• Weighted Random Early Detection (WRED)
• Committed Information Rate / Committed Burst Size (CIR / CBS)
32 Radisys Corporation Confidential
Poll Question 2
To adequately classify an LTE GTP-U packet stream
for QoS purposes, what degree of analysis is required?
A. QoS can be defined with a straight mapping based upon
assigned Tunnel Endpoint IDentifer (TEID)
B. Simple mapping from tunneled L3/L4 attributes (L4 port
number, DiffServ, Subscriber’s IP address, etc)
C. Parsing initial packets with a limited set of decision tree rules
to differentiate broad class of service (e-mail, video, http, etc.)
D. Signature analysis on early packets until a precise recognition
is made
E. Ongoing signature analysis in case the nature of the flow
changes
F. Can’t do any useful DPI because packets are encrypted
33 Radisys Corporation Confidential
Today’s Agenda
Market Dynamics
LTE QoS Fundamentals
LTE QoS Methods and Mechanisms
Policy Enforcement
Conclusion
Q&A / Wrap-up
34 Radisys Corporation Confidential
Unmatched Products & Expertise
Embedded
Wireless
Infrastructure
Solutions
Conclusions
LTE QoS Benefits
• User: Assures service delivery meets
expectations
• Operator: Can offer a wide variety of
services and monetize them
LTE QoS Challenges
• Requires coordination across all
business units to plan and execute
LTE QoS Opportunities
• LTE presents a tremendous
opportunity for mobile services to
grow faster than at any time in the
past
35 Radisys Corporation Confidential
Today’s Agenda
Market Dynamics
LTE QoS Fundamentals
LTE QoS Methods and Mechanisms
Policy Enforcement
Conclusion
Q&A / Wrap-up
36 Radisys Corporation Confidential
Q&A
Contact us!
Larry: [email protected]
James: [email protected]
For more information on our products, visit: www.radisys.com
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