Transcript project - Networked Software Systems Laboratory

Technion - Israel Institute of Technology
Electrical Engineering Faculty
Computer Networks Laboratory
“ACT”
Audio Conference over ATM
Network with TRM
Under the supervision:
Youval Nahum
Remus Koos
Michael Moreinis
Michael Maziar
Project Goals
•
•
•
•
Building the Audio Conference Manager
Implementation of Server-Client Messages
Communication Channels
Client-Server Relationship Structure
Description
• There is a significant need in fast & reliable
communication over computer networks
• One of the communication implementations is
AUDIO CONFERENCING
• In order to run the AUDIO CONFERENCE
convenient, the manager should be implemented
• The ATM Network doesn’t support reliable
connection - there is a need for IP control
connections.
Competitive Analysis
• Others Audio Conferencing tools
– Slow communication
– No manager implemented
• Audio conference with TRM
– Audio Transfer over ATM - fast communication
– TRM - fair management
• Weaknesses of ACT
– No user interface (at this point)
– No additional tools (whiteboard, video etc.)
Technology
• ATM Networks
– fast communication
– large data (audio) - low latency
• TRM - time resource manager
– fairness in time allocation
– no interference to speaker
• IP control connections
– reliable connection (necessary for control)
– standard communication protocol
Hardware/Software Resources
• Sun Workstations
• ATM Network cards FORE/ATM
• Native ATM API
• SUN Audio tools
- AudioRecord
- AudioPlay
- AudioTool - set the audio devices
Communication Channels
Host
Ethernet
Ethernet
Audio
Equipment
Audio
Equipment
Workstation
Workstation
Ethernet
Audio
Equipment
Workstation
ATM
Another channel is MULTICAST ATM connection
from server to each client
Request Queue
The FIFO QUEUE - "First In - First Out"
Each one of the
requests may be
withdrown at any
stage of execution
Client 1
Request
Client 2
Request
Client 3
Request
Client 4
Request
• Each client may have one request only
• Time allocation is equal to all clients
Client N
Request
Link List of Conference
Participants
Computer
address
Computer
address
Computer
address
Computer
address
ATM Thread
ID
ATM Thread
ID
ATM Thread
ID
ATM Thread
ID
IP Tread ID
IP Tread ID
IP Tread ID
IP Tread ID
IP socked
descriptor
IP socked
descriptor
IP socked
descriptor
IP socked
descriptor
Pointer on
next
Pointer on
next
Pointer on
next
Pointer on
next
• New participant - new member of LL is created
• Participant is down - member of LL is deleted,
Request Queue is updated
Client Software
Client Software
Ethernet
control
outgoing
connection
Ethernet
control
incoming
connection
• Each Client runs number of threads
• The treads cannot be switched by user
• Need for data locks
ATM
outgoing
simplex
connection
ATM
incoming
multicast
connection
Server Software
Server Software
CLIENT1
ATM
IP1
CLIENT2
IP2
ATM
• Audio Buffer
• Global Data Locks
IP1
Algorithm
routine
CLIENT N
IP2
ATM
IP1
Multicast
IP2
ATM
Server-Client Messaging
• Client Requests
– demand
– remove
– exit
• Client Messages
–
–
–
–
start
stop
exit
conference state messages
Server-Client Messaging
• Server Statistics
– Clients connected
– Request queue
• Server Timing
– Set-up the conference
– Conference timing
– Conference state messages
Conclusions
• Audio Devices
– Easy to implement
– Low quality
– High Latency
• ATM Networks
– Fast
– Unreliable connection
– Convenient for large data transfer
• TRM
– Improves the performance
– Fairness & Convenience
– Order in Conference