Multicast Transport Protocols: A Survey and Taxonomy

Author: Katia ObraczkaUniversity of Southern

CaliforniaPresenter: Venkatesh

Prabhakar

Contents Introduction Taxonomy Survey of Multicast Transport Protocols Conclusion

Introduction Earlier mechanisms

General solutions to the group communication problem

Recent trends focus on Multipoint interactive applications Data Dissemination applications

Taxonomy Data Propagation Reliability Mechanism Repair request Feedback Control Retransmission Flow and Congestion Control Locus of Control Ordering Group Management Target Application

Taxonomy Data Propagation

Multicast, some work with unicast too Reliability Mechanism

Receiver initiated through NACKs Special site for feedback control Avoiding losses Forward Error Correction Hybrid approach

Taxonomy Repair request and Retransmission

Point to Point or to the whole group NACK suppression Local recovery

Feedback Control Structure based - designated site or

control structure Timer based – probabilistic feedback

suppression

Taxonomy Flow and Congestion Control

Rate, window and token based schemes Layered Multicast – Encoding to different

layers Forward Error Correction techniques Representative based congestion control

Control Distributed Vs Centralized

Ordering Assigning sequence numbers

Taxonomy Group Management

Implicit or Explicit Variation: Authorization only while

joining Target Application

Generic ones Delay sensitive real time services Reliable transfers Resilience as opposed to reliability

General Purpose Protocols Reliable Broadcast Protocol

Multipoint communication between sites connected by a local broadcast network

Messages multicast through a token site Token site multicasts ACKs NACKs sent to Token site upon Packet loss Token site rotated among group members

General Purpose Protocols Multicast Transport Protocol

Reliable and globally ordered delivery Group Master coordinates members

Transmits tokens which provide ordering, congestion control

Group membership allowed only when all transmit tokens are with the master

Retransmission NACK based Uses fixed size transmission window

General Purpose Protocols Reliable Multicast Protocol

Name service advertises multicast groups, and flow and congestion control schemes

Dynamic group updation TCP-like congestion control – Timers,

ACKs and NACKs used to control window size

Reliability through multicasting NACKs

General Purpose Protocols Xpress Transport Protocol

Designed to support a wide range of applications

Explicit multicast group management protocol (MGM)

TCP-like fully reliable delivery, UDP-like best effort delivery and Fast NACK modes.

Sender can select ACK frequency Window and rate based flow control

General Purpose Protocols Uniform Reliable Group Communication

Protocol Reliable ordered communication

though a coordinator All sites keep history and coordinator

knows the most up-to-date site Reliable Multicast Framework

Provide framework to develop multicast protocols for various applications

Support for Multipoint Interactive Applications Multicast Transport Protocol-2

Immediate joins Master recovery Dynamic group parameter adjustment

Real-Time Transport Protocol Does not assure ordered reliable delivery RTCP used for control information Avoids packet losses using probabilistic

polling of set of receivers to compute rates

Support for Multipoint Interactive Applications Scaleable Reliable Multicast

Distributed protocol Group management by join and session

messages Log Based Receiver-Reliable Multicast

Logging server (LS) logs all packets LS ACKs senders and Receivers NACK LS Secondary logging servers used as

proxies and for local recovery

Support for Multipoint Interactive Applications Reliable Adaptive Multicast Protocol

NACK based reliable delivery Burst and idle modes Rate based flow control

Transport Protocol for Reliable Multicast Interactive Multimedia applications Group membership handled by

application Multicasting NACKs and probabilistic

NACK suppression

Support for Data Dissemination Services Muse

Posting multicast news articles Uses cryptographic checksums and

signatures on data for authentication Keep-alive messages

Multicast Dissemination Protocol Fragments files to MDUs Recovery by source asking receivers for

retransmission requests at end of transmission

Support for Data Dissemination Services Adaptive File Distribution Protocol

Group management done by a designated group secretary

No recovery mode for site failures or network partitions

Tree-Based Multicast Transport Protocol Control Tree Structure – Domain

manager Max tree degree defined ACKs and NACKs limited in scope

Support for Data Dissemination Services Reliable Multicast Transport Protocol

Control Tree – Designated Receivers Reclaim buffers on ACKs from children Window based flow control

Multicast File Transfer Protocol Modes: Unicast, Broadcast and Multicast Two pass Data Transmission protocol Open and closed Group Management

Interactivity Vs Reliabilty Resilient multicast delivery model Structure Oriented Resilient Multicast

Dynamic distribution graph Unicasts NACK to each parent Extended Ring Search (ERS) to look

for parents Nodes measure parents performance

and react to it Mechanism to avoid loops provided

Conclusion Summary

Survey and Classification of most Multicast Transport Protocols presented

Multicast Congestion Control – big research area

My Opinion Provides good pointers to the existing

protocols Emphasizes the Application Level Framing

trend in Multicast Transport Protocols