International Telecommunication Union
ITU-T
Resource and Admission Control
for NGN
Hui-Lan Lu, Ph.D.
Q.4/13 Rapporteur
Bell Labs, Lucent Technologies
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
Why?
ITU-T
NGN
802.xx
Access
Cable
Domain 1
IntServ
Domain 2 Domain 3 Domain 4
DiffServ MPLS-TE Over-Prov
2G/3G
Wireless
xDSL
Multi-Service Packet Transport
o Flawless support for a variety of applications (e.g., Web
services, VoIP and IPTV) with very different performance
needs
o Enabling providers to control end user experience in a
heterogeneous environment while protecting the networks
o Allowing fast introduction of performance-demanding
applications
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
2
Basic Network Requirements
ITU-T
o Ensure that only legitimate requests are satisfied
o Allocate and de-allocate resources (e.g., IP addresses,
port numbers, bandwidth) based on established policy
o Hide the network topology (e.g., IP addresses of all
but a few entities) as necessary
o Be able to handle remote NAPT devices
o Mitigate relevant denial-of-service attacks
Real-time application-driven resource management that
™ Preserves the separation of services and transport
™ Provides the necessary coupling to guarantee QoS and
implement security measures dynamically
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
3
Brief History + Building Blocks
ITU-T
o
o
o
1997: IETF has completed the Resource Reservation Setup Protocol
(RSVP)—a generally non-scalable per-flow end-to-end mechanism,
which has found a 2nd life in Multi-Protocol Label Switching (MPLS)
2002-2005: IETF has developed the Differentiated Services (DiffServ)
model, which supports traffic aggregation, and applied it to MPLS
2000-2005: IETF has developed the Common Open Policy Service
(COPS) protocol to exchange policy information between a policy
server (Policy Decision Point [PDP]) and its clients (Policy Enforcement
Points [PEPs])
• But other protocols (notably, RADIUS, DIAMETER, and H.248) have evolved
to be used for the same purpose
o
o
o
2000-present: 3GPP has adopted the IETF building blocks for ServiceBased Local Policy (SBLP), which is evolving into Policy and Charging
Control. 3GPP2 has a similar effort on Service-Based Bearer Control.
2003-present: ETSI TISPAN has been developing the Resource and
Admission Control SubSystem (RACS) based on SBLP
2004-present: ITU-T Q.4/13 has been developing RACF, with an end-toend scope from the onset, based on SBLP
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
4
RACF and NGN Framework Architecture
ITU-T
3rd Party Applications
Management Functions
ANI
Control
Media
Management
Application/Service Functions
Service
User
Service User
Profiles
Profiles
Service stratum
Transport User
Profiles
Service Control
Functions
Network
Attachment
Control Functions
Resource & Admission
Control Functions
Transport Control Functions
End-User
Functions
Other
Networks
Transport Functions
UNI
NNI
Transport stratum
See ITU-T Y.NGN-FRA
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
5
ITU-T RACF Architecture
ITU-T
(See ITU-T Y.RACF)
Service Control Functions
(part of IMS or other)
Service Stratum
Rp
Network Attachment
Control Functions
Ru
Rd
TRC-FE
Rt
PD-FE
Ri
RACF
intradomain
interdomain
Rn
TRE-FE
Rc
Rw
Transport
Functions
Policy Decision Functional Entity (PD-FE)
o Authorizes resource requests
o Configures the transport to enforce policy
PE-FE
service facing, transport independent
service independent,
transport dependent,
segment specific
Transport Resource Control Functional Entity
o Tracks resource usage & network topology
o Provides resource information to PD-FE
Policy Enforcement Functional Entity (PE-FE)
o Enforces policy for NAPT, gating, path
selection, rate limiting, packet marking, etc.
Other NGNs
Rs
Transport Stratum
typically part of border
transport elements (e.g.,
S/BCs, edge router)
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
6
More RACF Specifics
ITU-T
Support for
o Relative and absolute QoS, including priority
o Endpoints of varied QoS control capabilities
o Push and pull models for policy installation
o Multiple transaction models for resource requests
o Various resource management methods based on
accounting, measurement and reservation
o Existing and emerging transport QoS mechanisms
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
7
Push and Pull Models
ITU-T
Service Control
Functions
2
1
4
6
User
Equipment
2
Token
1
RACF
T
7
T
5
3
Service Control
Functions
Policy
5
RACF
6
Policy
3
4
T
8
Transport
Functions
User
Equipment
Push Model
Pull Model
Application Signaling
Transport
Functions
RACF Control
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
Transport QoS Signaling
8
Illustrative QoS Request Procedure
ITU-T
PE-FE
PD-FE
SCF
TRC-FE
1. Trigger
2. Resource initiation request
3. Policy decision
4. Resource initiation request/response
(availability check)
5. Final admission decision
(reservation and/or commit)
6. Resource initiation request
(reservation and/or commit)
Resource control session ID
Transport subscriber ID
Media flow description
Media priority
Media application class of service
...
7. Resource initiation
response
Resource control session ID
Transport subscriber ID
Media flow description
Traffic descriptor
IP QoS handling class
...
8. Resource initiation response
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
9
Configuration Example I
ITU-T
Service Control
Functions
Service Control
Functions
Service Control
Functions
Rs
Rs
Ri
Network
Attachment
Control
Functions
Rp
Rt
Rw
Rc
PE-FE
Rw
Rc
Rt
Rt
Rw
Rw
Rc
PE-FE
Core Network
Access Network
The PE-FE can reside in the
ƒ Session Border Controller
ƒ Access Node
ƒ Border Gateway
Network
Attachment
Control
Functions
TRC-FE
PE-FE
PE-FE
PE-FE
Ru
PD-FE
TRC-FE
TRC-FE
Rw
Customer
Premises
Equipment
/Network
Ri
PD-FE
PD-FE
Ru
Rw
PE-FE
Access Network
Customer
Premises
Equipmen
t/Network
ƒ Cable Modem Termination System
ƒ Gateway GPRS Support Node
ƒ Packet Data Serving Node
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
10
Configuration Example II
ITU-T
Service Control
Functions
Service Control
Functions
Rs
PD-FE
Ru
Network
Attachment
Control
Functions
PE-FE
TRC-FE
Rw
Rw
Rc
PE-FE
PE-FE
Access Network
Network
Attachment
Control
Functions
Rt
TRC-FE
Rc
Ru
PD-FE
Rt
Rw
Customer
Premises
Equipment
/Network
Rs
Core Network
Rw
PE-FE
Access Network
Customer
Premises
Equipmen
t/Network
• Core Network is over provisioned
• RACF is deployed per network segment as needed
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
11
Use Case: Link-Based Resource Management
ITU-T
CSCF
PDF
CSCF- Call Session
Control Function
CSCF
TRCF
Edge
Router
(PE-FE)
MPLS/DiffServ
Network
Enterprise
Network
Softclient IP Phone
Core Router
Edge
Router
(PE-FE)
Enterprise
Network
Softclient IP Phone
MPLS Path
o LSPs are set up a priori for routing the traffic of a specific application
o DiffServ is used for effecting the desired treatment of traffic
o RACF
9 Measures link utilization per service class periodically
9 Formulates blocking policy upon link congestion for affected paths
9 Makes admission decision per policy
9 Configures edge routers for the admitted traffic
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
12
Summary
ITU-T
ƒ Bridging service control and transport, RACF enables dynamic
application-driven resource management
• Application admission decision taking into account resource availability
• Preempting transport congestion from the service control layer
ƒ Augmenting native transport QoS support, RACF can be applied
edge-to-edge or end-to-end, and be realized in various ways
ƒ All network-controlled applications can make use of RACF for
performance assurance and network border control
ƒ The initial Recommendation on RACF (Y.RACF) is targeted for
consent in July
• Selection and development of RACF protocols is ongoing
• Next steps are to address open issues such as inter-PDF communication
(intra- and inter-provider) and coordination of transactions end-to-end
• Draft Recommendations Y.123.qos and Y.enet under development
apply RACF to specific Ethernet environments
ƒ Cooperation among related standards efforts across SDOs is
essential for achieving a consistent approach
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
13
List of Acronyms
ITU-T
o
o
o
o
o
o
o
o
o
o
o
o
o
o
CSCF: Call Session Control Function
GPRS: General Packet Radio Service
IMS: IP Multimedia Subsystem
LSP: Label Switched Path
NAPT: Network Address and Port Translation
NGN: Next Generation Networks
PD-FE: Policy Decision Functional Entity
PE-FE: Policy Enforcement Functional Entity
RACF: Resource and Admission Control Functions
RSVP: Resource ReserVation setup Protocol
S/BC: Session Border Controller
SDO: Standard Development Organization
TRC-FE: Transport Resource Control Functional Entity
TRE-FE: Transport Resource Enforcement Functional Entity
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
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