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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)[email protected]
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 [email protected]
http://ace.netmedia.gist.ac.kr/
Gwangju Institute of Science &
Technology