Download IMS + QoS

IMS & QOS
IMS Alphabet Soup and the need for Unified
Policy Management
Matt Tooley
CableMatrix Technologies, Inc.
Agenda
•
•
•
•
•
•
Review of Quality of Service (QoS)
IMS + QoS in theory
Policy Management
IMS + QoS in the real world
Putting it all together
Summary
3
Evolving Services
Moving beyond conversational SIP services
• Entertainment
– IPTV, VOD, voice
• Communications
– Voice, messaging,
collaboration
• Security
– DOS protection, device/user
quarantine
• Managed Enterprise
– Dynamic bandwidth allocation
• Fixed Mobile Convergence
(FMC)
– Service continuity, application
and network-aware QoS
4
Latency/Loss Sensitivity
Growing need for QoS
Video
Conferencing/Telephony
Voice
Streaming Video
Utilitarian – weigh lightly
on network
Console
Gaming
More exciting – weigh
heavily on the network
Game
Download
Low-end
Gaming
Legacy
Internet
Services
IPTV
Music
Download
Video
Download
Bandwidth Consumption
5
QoS 101 – What is QoS?
• Quality of Service (QoS) refers to control
mechanisms that can provide different
priority to different users or data flows, or
guarantee a certain level of performance
to a data flow in accordance with requests
from the application program.
• QoS is more than just bandwidth
–
–
–
–
Delay
Jitter
Priority
Packet loss
6
QoS 101 – Application Requirements
–
–
–
–
Constant bit rate service
Low latency, low jitter
Little or no packet loss
Guaranteed bandwidth
• Streaming Media
– Variable bit rate service
– Low jitter, low packet loss
– Guaranteed minimum bandwidth
• Real-time Gaming
– Variable bit rate service
– Low latency, low jitter
– Low packet loss
QoS Requirement
• Voice
• Web Surfing
– Best Effort
7
QoS 101 – QoS Models
• Differentiated Services (Diffserv)
– Provisioned QoS model
– Class of services
– Prioritized
• Integrated Services (Intserv)
– Signaled QoS model with admission control
– Flow-based QoS
– Parameterized
8
QOS Triggering Points – Push, Pull
• Push
– QOS pushed from
the network
– Network server
requests QOS upon
service initiation
• Pull
– QOS pulled by the
user/user equipment
– UE requests QOS
upon service
initiation
9
QoS Framework for NGN
Application Function
SIP
QoS
Control
SIP
IMS
Switching
Core
Policy
Manager
Core IP
Network
CPE
Access
Nodes
IP
Routers
10
IMS Architecture
IMS
Other IP/
IMS network
HSS
Control Plane
Mm
I-CSCF
Cx
Traffic Plane
I-CSCF
Cx
Mw
S-CSCF
P-CSCF
Mk
Mr
Gq Go
Mi
MRF
Gi
Mg
BGCF
Mj
UTRAN
Gi
PDF
Go
UE
IMSMGW
SGSN
Gi
GGSN
MGCF
SGW
Mn
Legacy/
PSTN
11
IMS Architecture - Simplified
SERVICE
PLANE
SCIM
(Service Broker Platform)
MRFC
QoS
S-CSCF
I-CSCF
HLR
P-CSCF
BGCF
PDF
MGCF
CONTROL
PLANE
HSS
RAN
Node B
BTS
WLAN
RNC
BSC
MRFP
MG
W
MG
W
SGSN
GGSN
PSTN
PLMN
Intranet/
Internet
TRANSPORT PLANE
12
IMS & QoS in Theory
• IMS elements involved with QoS
–
–
–
–
User Endpoint (UE)
P-CSCF / Application Function
PDF
Edge IP Router
• GGSN, BRAS, CMTS, Base station
QoS-related
application-level
parameters (e.g. SDP)
P-CSCF
Application
Function
Policy
Set-up info
Gq/Gq’
Policy
Decision
Function
Policy
Decisions
Go
UE
Access
Network
Policy Decision
Decisions
concerning
Service Based
Local Policy
Policy Enforcement
Diffserv, Intserv QoS
parameters, etc
GGSN, CMTS,
BRAS, ASN-GW
13
IMS based QoS (1/3)
• IMS based QoS
– Supports a minimum bandwidth required by a
service based upon PDF’s QoS decision and
IP edge node resources
– PDF’s QoS decisions based upon IMS
signaling and operator policy rules
• Application level E2E QoS negotiation
– End-to-End QoS requirements are negotiated
via SIP/SDP offer/answer model signaling
14
IMS based QoS (2/3)
• Mechanism for E2E QoS authorization
– SDP Inspection
• SDP media parameters are examined based upon local
policy, configuration of operators or user subscription
• If there are any media parameters which are not allowed
on the network, CSCF returns a 4XX (Not Acceptable
Here) response
• UE, P-CSCF, S-CSCF, and AS perform SDP inspection
– Session Based Local Policy (SBLP) based
authorization
• P-CSCF generates the service information from SDP and
sends it to PDF
• PDF authorizes the QoS requirements from IMS-Proxy
based on operator policy rules
• PDF saves authorization results
• PDF authorizes the QoS requirements for IP Edge Node
based upon SBLP
15
IMS based QoS (3/4)
SDP Inspection
UE
P-CSCF
S-CSCF
AS
SDP
SDP inspection
performed
based upon
Local Policy
SDP inspection
performed
based upon
Local Policy or
User
Subscription
AS checks SDP
and request
confirmation for
resource
reservation at
the endpoint
16
IMS based QoS (4/4)
5 Authorization
Token
3 Service
Information
P-CSCF
Application
Function
2 QoS
negotiation
1 – SDP from
UE1
4 – QoS
Authorization
6 SDP from
UE 2
Policy
Decision
Function
7 QoS Authorization
and Commit when
bearer channel
authorization requested
UE1
GGSN , CMTS ,
BRAS, ASN-GW
Media Path
UE2
17
Policy Control Key to Managing QoS
• Business and network orchestration
– Subscriber & network policy enforcement
• Media authorization interface
– Standard interface between applications and the
network for signaling QoS requests
• Real-time service execution
– Dynamic network resource control enables assured
delivery of services
• Enhanced network utilization
– Intelligent admission control guarantees quality and
maximizes transaction value
• Creates new business opportunities
– Charging, partnering,…
18
Alphabet Soup
• 3GPP
– Release 6: PDF – Policy Decision Function
– Release 7: PCRF – Policy Control and Charging Function
• 3GPP2
– PCRF – Policy Control and Charging Function
• TISPAN
– RACF – Resource Admission Control Function
• CableLabs
– PS – Policy Server
– PAM – PacketCable Application Manager
• WiMAX
– Release 1: PF - Policy Function
– Release 1.5: ???
19
IMS & QoS Ideal Case
CSCF
Session Control Plane (SIP)
PDF
Resource Control Plane
UMTS
20
IMS & QoS Real World
Session Control Plane (SIP)
CSCF
PDF
PDF
PDF
Resource Control Planes
DSL/
Cable
3G
WiMAX
21
Problems with this approach
• Requires CSCF to support
multiple policy signaling
interfaces
• CSCF needs to know
information about the
transport layer
• QoS Levers
– 3G & DSL – Min & Max
bandwidth
– Cable & WiMAX
• Shared Media
• Min & Max bandwidth
• Scheduling –Jitter &
Latency
Session Control Plane(SIP)
CSCF
PDF
PDF
PDF
Resource Control Planes
DSL/
Cable
3G
WiMAX
• No good support for nonSIP based services
• NAT
22
IMS & QoS Real World – The Solution
Session Control Plane
Application
Function
(non-SIP)
CSCF
(SIP)
Resource Control Plane
Policy Server/Policy
Decision Function
Cable/
DSL
3G
WiMAX
Transport Plane
23
Benefits of Unified Policy Management
• CSCF is network agnostic
– Does not need to know any transport layer information
• Enables seamless QoS handovers across networks
– PDF has visibility of all network resources across all its
networks
• Consistent service levels regardless of network
– PDF converts QoS from network agnostic form to network
specific form
• Supports services beyond SIP conversational services
– IPTV, internet video, on-line gaming, ….
• Supports Policy Peering for inter-service provider services
– Centralized policies minimizes interfaces across peering
points
24
Summary
• Keys to success
– QoS is required delivering services over IP
– Policy management is required for
orchestrating QoS requests for applications
– Centralized policy management assures all
applications work equally well regardless of
the network
25
Thank-You
Matt Tooley
CTO
CableMatrix Technologies, Inc
http://www.cablematrix.com
[email protected]
(847) 294-0600
Acronyms
• AF – Application Function
• AS – Application Server
• ASN-GW – Access Service
Network Gateway
• BRAS – Broadband remote
access server
• BS – Base station
• CMTS – Cable modem
termination system
• CPE – Customer premise
equipment
• DOS – Denial of Service
• E2E – End to End
• FMC – Fixed Mobile
Convergence
• GW – Gateway
• IMS – IP Multimedia
Subsystem
• PDF – Policy Decision
Function
• PF – Policy Function
• QOS – Quality of Service
• SDP – Session Description
Protocol
• SBLP - Session Based
Local Policy
• SIP – Session Initiation
Protocol
27