Contentbased TCP

1
Content-based TCP

• CMSC818L project report
• Chunyuan Liao
• Univ. of Mayland,May.13 2002

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Motivation

• Reliable, ordered TCP is necessary
• Mobility increase the difficulty
• Current TCP/IP binds the name and the address
• Low efficiency and bad scalability
• Content-based network can provide support
• Content-based routing/location achieves
  Late-bind
• Mobility becomes very natural

3
Basic Ideas

• Replace the IP address with key of the
  application
• Furthermore, improve the efficiency and
  robustness with
• Multiple sending-buffers
• Connection split
• Multiple Acknowledgement

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System Architecture

• Applications
• Identified with App-ID
• Content-based TCP
• Reliable, ordered transportation
• Intelligent Surrogate
• Content-based Network
• Routing/location
• Detect status of Nodes
• Underlying Network

Applications
CB-TCP
CBN
Underlying net
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Implementation(1)-Basic mode
App2

• Format of Package
• Dest. App-ID
• Dest. Port
• Session
• Source App-ID
• Source Port
• Seq.
• ACK
• Key strategy of ACK
• Directly send ACK
• back to who sent data

CB-TCP
CBN
ltApp2,port2,Sessiongt
Underlying net
ltApp1,port1,Sessiongt
ltApp1,port1,Sessiongt
ltApp2,port2,Sessiongt
App1
App1
CB-TCP
CB-TCP
CBN
CBN
Underlying net
Underlying net
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Implementation(2)-Multiple Sending buffer

• Motivation
• Incoming data determines the apps execution
• Sent data have nothing to do with app any more
• Agent
• Different source to the same dest.
• Transparent to Dest.
• Issue of ACK
• Lazy mode
• Wait for retransmission
• Proactive mode
• Send buffered data
• Send Ask for ACK

App2
CB-TCP
CBN
ltApp2,port2,Sessiongt
Underlying net
ltApp1,port1,Sessiongt
ltAgent,port3,Sessiongt
ltApp2,port2,Sessiongt
Agent forApp1
App1
Pack49 CB-TCP
Pack13 CB-TCP
CBN
CBN
Underlying net
Underlying net
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Implementation(3)-Connection Split

• Motivation
• Reduce the package retransmission as much as
  possible
• Improve robustness
• Agent
• Transparent to the source
• Possible Multiple agents for the same dest.
• When the dest. revives, multiple agents become
  multiple sources
• Issue of Multiple agents
• ACK just for single package
• Sequence in agents buffer is possibly not
  successive
• Ignore-Sequence flag in ACK

Package
App2
App1
Agent
ACK
CB-TCP
CB-TCP
CB-TCP
CBN
CBN
CBN
Underlying net
Underlying net
Underlying net
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Implementation(4)-Multiple replicas

• Motivation
• Improve robustness, ensure there are K replicas
  on the path
• Issue of ACK
• Transparent to source and previous agents
• ltDest.AppID, Dest.Port,Sesgt remains unchanged
• ACK receiver list with K entries, not just the
  source App.
• Condition for buffer release
• K ACKs have been received
• Or the source of an ACK package is the
  destination
• Agents set Ignore-Sequence flag in ACK

Source
Agent1
Agent2
Dest.
CB-TCP
CB-TCP
CB-TCP
CB-TCP
CBN
CBN
CBN
CBN
Underlying net
Underlying net
Underlying net
Underlying net
Example K 2
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Related work

• Tapestry/Pastry
• Test bed for Content-based TCP
• Mobile IP
• Bad locality
• Low scalability robustness
• Simple funtionality
• ATP(Autonomous Transport Protocol)

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Summary

• Basic Idea replace IP with a Key
• Multiple sending buffer
• Connection split
• Multiple replicas

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Thank you! Good luck in final exam !