AT

AT&TAMT Multicast Trials

Patricia [email protected]/09/2009

Outline

Page 2

• AT&T Trial Activity – AMT Multicast

• Motivation

• Overview of Trial

• Technical Learnings

• Opportunities for Further Discussion

• Improved standardization & development

AT&T AMT Multicast – Motivation

• Multicast will play a critical role in cost-effective delivery of content for both network and content providers

• However, the Internet is not currently universally multicast capable – especially broadband access networks and home network equipment such as RGs (Residential Gateways)

• As an interim solution, use AMT (Automatic IP Multicast without Explicit Tunnels)(1) to tunnel through non-multicast-capable networks

(1) IETF Draft “draft-ietf-mboned-auto-multicast-09”, June 27, 2008

Page 3

Automatic Multicast Tunneling

PCATM

Broadband Access POPs AggregationSubscriber PremisesCore POPs

Typical Current NetworkAccess Router

Access Router

Core Router

Core Router

Hub Router

BRAS DSLAM RG

HR

CE

CE

Native-Multicast End-to-End

PCEthernet


Multicast Network - TargetAccess Router

Access Router

Core Router

Core Router

Hub Router

BRAS DSLAM RG

HR

CE

CE

Native-Multicast Backbone Tunneled-Multicast Access

Multicast Network with AMT

ATM


Access Router

Access Router

Core Router

Core Router

Hub Router

BRAS DSLAM RG

HR

CE

CE

AMT Relay

PC

AMT Client

Multicast capable and ready

Multicast incapable

Page 4

AT&T AMT Multicast TrialsOverview

• Use PIM-SSM (Protocol Independent Multicast – Source Specific Multicast) over AT&T multicast-capable CBB (Core Backbone) network

• AT&T-developed AMT Relay and GW (Gateway)

• End-to-end Service delivery perspectiveIntegrated with AT&T CDN (Content Delivery Network)

• Content-request handling/routing logic• Coexistent with unicast• Service Logic interacting with PC Client• Seamless failover• Service Assurance• Accounting/Reporting• AAA (future)

Page 5

AT&T AMT Multicast Trial Architecture

Content Ingest

AT&T Multicast Enabled Network


Non Multicast Enabled Networks

AMTRelay

AMTRelay

Multicast Media Server

ICDS Unicast Delivery

Unicast delivery to end users without AMT multicast capabilities

AMTGW

AMTGW

AMTGW

AMTGW

4

3

1 End user requests content and is routed to CDI

2

3

4

CDI scans end user PC for multicast capabilities, enables download of AMT GW, if necessary, and provides multicast source and group address (S,G) to PC

End user PC sets up tunnel with nearest AMT Relay and joins multicast stream to receive content

CDI determines that multicast is an available technology for this content delivery

Content Delivery

Intelligence

2

Existing ICDS(1) Component

Multicast Service Component

Multicast Network Component

UnicastMulticast

AMT MulticastSignaling/Data

Page 6

1

(1)ICDS – AT&T Intelligent Content Distribution Service

AT&T AMT Multicast TrialsWhat has worked well

Page 7

Quality of AMT multicast perceived as good as unicast

Pushing GW client, as needed

Pushing appropriate stream to user

Anycast Routing for AMT Relays

Content Ingest




AMTRelay

AMTRelay



AMTGW

AMTGW

AMTGW

AMTGW

Content Delivery

Intelligence

UnicastMulticast


Handling home network environments (e.g. multiple PCs behind NAT, WiFi)

Performance & scalability of Relay (Server-based for Trial)

Tuning MTU on Media Server to accommodate AMT encapsulation and avoid fragmentation

Accounting information uploaded from PC

AT&T AMT Multicast TrialsFailure Recovery Model

Page 8

Content Ingest


AMTRelay

AMTRelay



AMTGW

AMTGW

AMTGW

UnicastMulticast


1

2

4

AMT Relay advertises anycast route for Discovery. Once GW discovers Relay, uses its unicast address.

AMT GWs can detect Relay failure and “Rediscover” new Relay

1 AMT Relay fails mid-stream

Example:

2 AMT GW detects failure and Rediscovers alternate Relay

Rejoins stream via alternate Relay

3

3

If Media Player times out before stream resumes, should fail over to unicast in playlist

4

AT&TMulticastEnabledNetwork

Media Player should allow failover from one stream to another on playlist (last one unicast)

Multicast media servers could also use anycast for their source address

Unicast media server redundancy as today

AT&T AMT Multicast TrialsTechnical Learnings

• Multicast in General• Multicast not universally supported on client devices/players

In particular need IGMP V3• Trials so far limited to:

• Windows XP, Vista• Windows Media Player

• Presence of IGMP V2 causes PC with AMT GW, Relay to downgrade from V3 – incompatible with PIM-SSM

• AMT-Related• Firewall issues blocking AMT Port in corporate environments -

Network & PC based• Allowing native multicast when available (i.e. AMT GW

seamlessly turning on/off as needed)

Page 9

Technical LearningIGMP V2 Presence on LAN

Page 10




AMTRelay

AMTRelay


AMTGW

AMTGW

AMTGW

UnicastMulticast


Home router is IGMP V2

PC reverts to V2

Cannot join (S,G) via PIM-SSM without

mapping

IGMP V2 Querier

Content Ingest


1

2

3

4

Causes PC to revert to V2

Though playlist pushed to PC has (S,G), Media Player issues V2 join (*,G)

Unicast delivery is required

Without mapping configured, Relay cannot make PIM-SSM join and AMT fails

1

2

3

4

5

5

Technical LearningChanging User Network Environments

Page 11

UnicastMulticast




User in officeAMT GW should

not intercept IGMP joins

CorporateIntranet

(Multicast capable)

User/End Device moves

User/end device moving between environments (native multicast, AMT, unicast-only)


AMTRelay

AMTRelay


AMTGW

User at homeAMT GW pushed for multicast content

AT&T MulticastEnabledNetwork

Don’t want AMT client to intercept and Discover Relay in native multicast capable setting

Opportunities for Further DiscussionImproved standardization & development

Page 12

• Multicast in general

• Support multicast (IGMP V3) in all devices/media players, OS

• Media Players should support mid-stream failover in playlist

• Ability to override IGMP V2 downgrade or selectively ignore V2 queries

• AAA-like function for multicast

• Service Assurance

• AMT-Related

• Firewalls - consistent approach to allowing AMT port

• AMT Relay function integrated into network platforms

• AMT GW function integrated into end user software and transparent to end user

• Where to integrate AMT GW in home environment?

• On each client as separate host,

• On RG, modem, or home router, or

• On “always-on” host acting as GW

Backup Slides

Page 13

Opportunities for Further DiscussionHome Network Configurations

Page 14




AMTRelay


AMTGW

AMTGW

UnicastMulticast


Variations in home networks:• NAT behind modem/router or DMZ/sharing

public ip address

• WiFi/Wired

• PPPoE on end device or modem, 1483B, etc.

Where to integrate AMT GW in home environment?

•On each client as separate host,

•On RG, modem, or home router, or

•On “always-on” host acting as GW (not shown)

AMTGWWeb TV

Box

iPhone

BroadbandModem/Router

RGAMTGW

e.g. Android

AMTGW

AMT GW could be incorporated into end device

AMT GW could be incorporated into home GW device

AMTGW

AMTGW

AMTGW

OR

BroadbandModem/Router

AMTRelay

• Devices – PCs, TVs, mobile phones/PDAs

• Variations in PC OS, Media players, browsers, firewalls

Glossary

Page 15

AAA Authentication, Authorization, and Accounting

AMT Automatic IP Multicast without Explicit Tunnels

BRAS Broadband Remote Access Server

CBB Common Backbone

CDN Content Delivery Network

GW Gateway

HR Home Router

ICDS AT&T Intelligent Content Distribution Service

IGMP Internet Group Management Protocol

NAT Network Address Translation

PIM-SSM Protocol Independent Multicast-Source Specific Multicast

RG Residential Gateway

WMP Windows Media Player

AT

Documents

multicast stream

page quality of amt

multicast capable

amt port

amt encapsulation

amt gwscan

native multicast

amt automatic ip multicast