International Telecommunication Union
ITU-T
Home Gateway Initiative
Phase 1 QoS Architecture
Duncan Bees
Technical Advisor, PMC-Sierra
HGI QoS Technical Group Deputy-Chair
Duncan_Bees@pmc-sierra.com
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
Why the Home Gateway Initiative?
ITU-T
o Unavailability of Home Gateways providing full
support to the telecom operators’ requirements for
triple play services
o Unavailability of reliable, flexible, cost effective
end-to-end solutions (access network + HG + home
network architecture) for multiple-play services
able to satisfy first of all the customers and, of
course, the service providers and manufacturers as
well
o The Home Gateway is not seen as a generic
advanced modem-router, but a service enabler
device and an added value for both the customer
and the service provider
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
2
HGI Timeline
ITU-T
o December 15th 2004, founded by 9 members
o March 2nd 2005: official launch
o 69 members (1/4 Telcos) as of April 5th 2006
o July 3rd 2006, official publication of Rel.1
specs
o 1Q-2Q2007: Release 2
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
3
HGI Phase 1 Gateway Architecture
ITU-T
Service support
Management
Maintenance
DDNS
ALGs
Diagnostics
VoIP termination
Performance monitoring
Voice/comm. services
FW upgrade management
QoS management.
Security management
Security
Device management
Firewall policies
Local management appl.
Key management
Authentication
Remote management client
Control functions
4
Processing performance
Basic System features
Powering
Configuration management
Device discovery
Quality of Service
DHCP, PPP, SIP,
IGMP handling
Classification
Queuing
Mapping
PSTN
interface
WLAN
security
Packet processing
Classification
Queuing/Scheduling
Routing/NAT
Bridging
Filtering/Encryption
Multicast to unicast conversion
WAN
Interfaces
Data flow
Management flow
LAN
interfaces
Control flow
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
4
QoS Goals
ITU-T
o Management of key congestion points
• Potential rate mismatches abound
o Traffic classification and prioritization
• Goal is identification of Service Class
• Telco-managed services vs unmanaged services
• Special attention for voice/video
o Handle Diverse flows in the HG:
• WANÆLAN (downstream)
• LANÆWAN (upstream)
• LAN-LAN (transit)
o Focus on QoS handling within the HG
• With guidelines for LAN components
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
5
Congestion Points
ITU-T
100
Mbps
HG
Low-rate
upstream
Access
100
Mbps
High-rate to
low-rate
bridge
High-rate
downstream
Access
ADSL example with
upstream/downstream mismatch
Merging
WAN-LAN
and transit
traffic
100
Mbps
100
Mbps
Ethernet
Switch
100
Mbps
Wireless
LAN
<10 Mbps
Ethernet-PLT
bridge
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
6
Managed vs Unmanaged Services
ITU-T
o A managed service is a service for which the service
provider provides preferential treatment (that can
include QoS)
• IPTV
• Voice
• Could also include classifiable LAN-LANflows
o Unmanaged services: an unmanaged service is a
service for which the service provider has no
commitment to the customer (specially in terms of
QoS).
• Could be: Internet access, peer-peer, general LAN
flows….
o Distinguished via classification in the HG
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
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Flow types - details
ITU-T
o Managed Services are typically WAN ÆLAN or LAN
Æ WAN
o LAN-LAN flows are a “grey zone”. Typically these
are unmanaged, BUT
• Service provider may wish to provide QoS assistance
to some LAN-LAN flows
• Example: VoD download to be streamed to STB at a
later time across the home LAN.
o Means to prevent LAN-LAN flows from disrupting
managed WAN Æ LAN flows
• Fixed queue allocation scheme
• Optional deep classification of LAN-LAN flows
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
8
QoS Datapath Functions
(LAN Side Ingress)
ITU-T
Upstream
Congestion
Management
LAN Ingress 1
LAN Ingress 2
LAN Ingress n
Classifica
tion
DSCP &
L2
Marking
WAN
Class
shaping &
queuing
WAN Egress 1
WAN Port
Scheduler
& Shaper
WAN Egress 2
WAN Egress n
Bridging, NAT/
Routing, Firewall
LAN Egress 1
HG traff ic
source
LAN
Congestion
Management
LAN
Queuing
LAN Ports
Scheduler
LAN Egress 2
LAN Egress n
HG traf fic
sink
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
9
QoS Datapath Functions
(WAN side Ingress)
ITU-T
WAN Ingress 1
WAN Ingress 2
LAN Egress 1
Classifica
tion
DSCP &
L2
Marking
Bridging, NAT/
Routing, Firewall
LAN
Congestion
Management
LAN
Queuing
LAN Ports
Scheduler
LAN Egress 2
LAN Egress n
WAN Ingress n
HG traffic
sink
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
10
Use of DSCP and Layer 2 Markings
ITU-T
o The HG provides capabilities of classification and
marking at layer 3 (DSCP)
o Layer 2 classification in the HG may also be
supported
o Generally, layer 3 markings (DSCP) are preferred
within the LAN
• We do not wish to encourage use of VLAN/p-bit tags
within the LAN due to concern about ability of
already installed equipment to handle them
— Must recognize, though, that these tags may be encountered
• DSCP is our preferred mechanism to transmit priority
information to wifi, powerline, etc.
• Recommended DSCP markings consistent with DLNA
ITU-T Workshop on “End-to-End QoE/QoS“
usage
Geneva, 14-16 June 2006
11
Classification
ITU-T
o Classification requirements well delineated
• WAN ingress
— Multifield classification upon layer 4, IP and ethernet
fields
• LAN ingress/WAN egress
— Multifield classification upon layer 4, IP and ethernet
fields
• LAN ingress/LAN egress
— Typically, simpler classification based only on MAC
SA/DA
— Exception handling (multifield classification) for traffic
destined to specified LAN ports
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
12
Queuing
ITU-T
o Egress queuing model
o Packets are slotted into egress queues
depending on classification and forwarding
decisions
o Queue requirements
• WAN egress – min 5 queues, 8 suggested
— strict priority and WRR scheduling
o
Allows lowest latency to be accorded to voice and
flexible allocation to other services
— shaping at class and port levels
• LAN egress ports – min 4 queues
— strict priority and WRR scheduling
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
13
Queuing Configuration Example
ITU-T
Direction
Purpose
Scheduling into Port
Upstream
Voice
Strict Priority (highest)
Upstream
Video
Strict Priority (next)
Upstream
Temporary Voice
W1 Weighted Round Robin
Upstream
W2 Weighted Round Robin
Upstream
Premium Data, GPRS Data,
Game Data
Best Effort Data
Downstream
Value Added Services
Strict Priority (highest)
Transit
Value Added Services
Strict Priority (next)
Downstream
Best Effort Data
W2 Weighted Round Robin
W3 Weighted Round Robin
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
14
Overload Protection
ITU-T
o An optional mechanism is defined aimed at
preserving QoS of managed service flows in
the upstream
o Requires identification of flow instance using
classification
o Before admitting a new managed service
flows to the premium queue, performance is
first tested in a lower priority queue
o This mechanism ensures that already
identified flows will not be adversely
impacted by newly admitted flows
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
15
Congestion Management
ITU-T
o Congestion management is a required
configurable capability on all queues
• Random Early Discard
o The purpose is to improve performance of
TCP oriented traffic in the presence of
congestion
• Particularly applicable to upstream link
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
16
Management of QoS Functions
ITU-T
o Phase 1 release of HGI builds upon DSL
o
o
o
o
Forum protocols for managing HG QoS
capabilities
Management from a service provider’s AutoConfiguration Server (ACS)
TR-069 (CWMP) protocol
TR-098 Data Model
HGI specific QoS profile for TR-098
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
17
What We Did NOT Cover
ITU-T
o Connection Admission Control
• No full CAC, although we have a simplified
CAC and some flow awareness (in the
overload protection scheme)
• Full CAC requires generalised flow awareness
+ parameterisation of bandwidth and this is a
topic for Phase 2 study
o Interaction with LAN QoS signaling, e.g.
UPnP QoS
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
18
Phase 2 Goals
ITU-T
o HGI Phase 2 goals are just being developed
o Increased focus on services such as fixed-
mobile convergence
o Initial QoS study areas
• Revisiting VLAN support in LAN
• CAC
• UPnP QoS
• User control over QoS policy
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
19
ITU-T
THANKYOU
Questions?
ITU-T Workshop on “End-to-End QoE/QoS“
Geneva, 14-16 June 2006
20