DEPT. OF INFO. & COMM., GIST

AG connect: Toward better connectivity

for the AG

19th APAN Bangkok Meeting (2005. 1. 25)

Namgon Kim and JongWon Kim

Networked Media LaboratoryDept. of Information & Communications

Gwangju Institute of Science & Technology (GIST)jongwon@netmedia.gist.ac.kr

http://ace.netmedia.gist.ac.kr/

DEPT. OF INFO. & COMM., GIST

Contents

Access Grid (AG)AG Connectivity Problems

Unicast networksNetworks behind Firewall and NATLow capacity nodes

Connectivity Solution for High-Quality VideoStructure of High-Quality Video for AGModification of AG StructureModified QuickBridge

Implemented ResultConclusion

DEPT. OF INFO. & COMM., GIST

Access Grid (AG)

Support group-to-group interaction across the GridAccess Grid does for people what the computational Grid does for machinesMuch more than teleconferencing, if possible at commodity pricesTo enable groups of people to interact with Grid resources and to use the Grid technology to support group to group collaboration at a distance

Distributed Lectures and seminarsRemote participation in panel discussionsVirtual site visits meetingsComplex distributed grid based demonstrations

DEPT. OF INFO. & COMM., GIST

AG Connectivity Problems (1/3)

Multicast ConnectivityAccess Grid uses multicast for multimedia deliveryMulticast is bandwidth efficient

Multicast-disabled networksUnicast networksNetworks under ISP’s control

Multicast failures compromise the usability of the Access Grid

AG Node

ISP Networks

Multicast Network

AG Node

AG Node

AG NodeAG Node

Unicast Networks

DEPT. OF INFO. & COMM., GIST

AG Connectivity Problems (2/3)

Firewall and NAT transitionFirewall

Packet filtering and Protocol end pointA multicast packet sent over the Internet will never be seen on the intranet, unless such packets are explicitly relayed by the firewall

NAT (Network Address Translation)Unidirectional connection initiation only

– Only hosts behind NAT can initiate the connection Behind Firewall

Multicast Network

AG Node

AG Node

AG Node

Behind NAT

AG Node

AG Node

Firewall

NAT

AG Node

AG Node

DEPT. OF INFO. & COMM., GIST

AG Connectivity Problems (3/3)

Problems due to low capacity for dataSystem is under multicast-enabled networkBut due to lack of capacity, have difficulties in handling data

Nodes under Low network bandwidthNodes in small network bandwidth can not receive multimedia data

Nodes with Low performance SystemNodes with poor system performance can not process received data

AG Node

AG Node

AG Node

Low Bandwidth

Network

Low Performance

Node

DEPT. OF INFO. & COMM., GIST

AG Connector

Vision of AG ConnectorA solution for all these connectivity problems

1. AG Connector for Unicast Nodes2. AG Connector for Networks behind firewall3. AG Connector as a proxy

For users with low system performanceFor users with low network bandwidth

Multicast Network

Node 2Node 1

UMTP Agent 1

Node 2

Node 3

UDP Tunnel

Unicast Network

Node 1

1

2

FirewallLow

Performance Node

3

Unicast Node

Low Bandwidth

NodeUMTP Agent 2

DEPT. OF INFO. & COMM., GIST

Connectivity Solutions for High-Quality Video

Modify QuickBridge to support AG with High-Quality VideoA connectivity solution for AG with High-Quality Video

AG with High-Quality VideoLimitation of current Access Grid Toolkit (2.1.x)

Low-resolution VIC-based video (300Kbps CIF sized image)

High-Quality video services for Access Grid Toolkit is developed to promote advanced collaboration environment

HDV (1280x720)/DV(720x480) support

MotivationCurrent QuickBridge of AG is not applicable to AG with High-Quality VideoAG with High-Quality Video is using two multicast addresses

Session multicast addressVideo multicast address

Modify QuickBridge to provide connectivity solution for AG with High-Quality Video

DEPT. OF INFO. & COMM., GIST

Structure of High-Quality Video for AG

MotivationLimitation of existing video services in supporting high-quality video

FeaturesVersatile Video Format SupportMultimedia Session Management

Enable AGTk to support various video formats via an unified interface

Multicast-enabledNetwork

AG Node

AG Node

AG NodeHDV

DV

Stereo

Versatile Video Formats

DEPT. OF INFO. & COMM., GIST

Flexible Multicast Address Allocation

A Shared multicast address for every Video Consumer ServiceSession multicast addressVideo Consumer service gets video stream list from session multicast address

A unique multicast address per each Video Producer ServiceVideo multicast addressLet each AG node can receive video streams selectively.Can allow the sender share multicast address, if it is required

Multicast 1

Video stream 1 Video stream 2

Video stream 3

Multicast 2

Multicast 3Video stream 4

Multicast 4

SelectVideo 1, 3

DEPT. OF INFO. & COMM., GIST

Lack of Multicast Bridge Service

To utilize flexible multicast address allocation, High-Quality Video for AG modifies structure of AG

Uses more than two multicast addresses for one High-Quality Video Session

Modified Structure of High-Quality Video for AG isn’t compatible with current AG Structure

Current AG uses only one multicast address for a sessionQuickBridge is only for one shared multicast address

To provide Multicast Bridge Service, AG must store two kinds of info.

One for session multicast address, the other for video multicast addressNeed to modify current AG’s structure to provide storage for multiple multicast addresses

DEPT. OF INFO. & COMM., GIST

Modification of AG Structure

EVS (Extended Video Service) is the implementation of High-quality video service

Modification of Access GridModify EVS Stream Description to store these two bridges’ information Execute video application using information received from SAP (Session Announcement Protocol)Provide a way for high-quality video producer to keep its video multicast address

Modification of QuickBridgeModify QuickBridge of AG to create multicast bridge for each multicast addressStores mapping information between multicast address and unicast addressMulticast Bridge for session multicast address does translation of SAP messageTranslate SAP message to fit the connection type of consumer

DEPT. OF INFO. & COMM., GIST

EVS Stream Description

EVS Stream DescriptionModify EVS Stream Description to store Multicast Bridge information for EVS StreamProvide a way for high-quality video producer to keep its video multicast address

Bridge ServerModify Bridge Server to create Bridge for two multicast addresses of EVS

Venue

EVSStream

Video TXAddress

AudioStream

VideoStream Bridge Server

EVS StreamSession Address

location

dvlocation

BridgedSession Addr

Video TXAddress

Bridged Video TX Addr

DEPT. OF INFO. & COMM., GIST

Modified QuickBridge (1/2)

Bridge Server stores Bridge information when it makes a new Bridge

Information about the relation between multicast address and unicast addressUnicast MappingsMulticast Mappings

Bridge for Session multicast addressAnalyzes session information, and transforms it according to the network connection type of EVCSFor a EVCS which uses multicast bridge, Bridge sends all information as unicast formFor a EVCS which uses multicast, Bridge sends all information as multicast form

DEPT. OF INFO. & COMM., GIST

Modified QuickBridge (2/2)

DV|Netmedia|udp://@224.2.2.1:51256|224.2.2.1|51256

Unicast MulticastAnalyzer

Bridge for Session

Bridge Server

Unicast Mappings51256 63412

5326 64250

Multicast Mappings63412 224.2.2.1, 51256

64250 224.2.2.5, 51326

Request

DV|Netmedia|udp://@203.237.53.24:63412|203.237.53.24|63412

Response

51256 63412

DEPT. OF INFO. & COMM., GIST

Implemented Result

Multicast Network QuickBridge Server

User A

User B

DV Stream

DV Stream

Unicast Network

SAP Client of User BSAP Client of User A

Multicast user uses multicast address

Ex) 224.2.160.98:61282 - Unicast user uses QuickBridge Server Ex) 203.237.53.24:50124

- QuickBridge doesn’t redirect unicast user’s own video stream

DEPT. OF INFO. & COMM., GIST

Conclusion

Connectivity Solution for High-Quality VideoModify Quick Bridge to provide multicast bridge to High-Quality Video for AGAccess Grid

Modify EVS Stream Description to store these two bridges’ information Execute video application using information received from SAP

QuickBridgeCreate multicast bridge for each multicast addressTranslate SAP message to fit the connection type of consumer

Future WorkImplement AG Connector

Use tunneling with EncapsulationProvide connection with AG by Shared Application

DEPT. OF INFO. & COMM., GIST

Thank you!Send Inquiry to ace@netmedia.gist.ac.kr

http://ace.netmedia.gist.ac.kr/

Gwangju Institute of Science &

Technology