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Evolution of Multicasting


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									The Evolution of Multicast

    Research paper presented by
    Ajith M Jose (u4083453)
    The Evolution of Multicast
This presentation discusses about:

•    General Information about Multicast
•    Importance, types of Multicast
•    Description of Std IP Multicast Model
•    Evolution of MBone
•    Evolution of Intra-domain Multicast
•    Evolution of Inter-domain Multicast
•    Deployment of Inter-domain Multicast
 The Evolution of Multicast
1988     Std IP Multicast Model     Single flat

1992   Multicast Backbone (MBone)

1994     Intra-Domain Multicast

1997     Inter-Domain Multicast     Hierarchical
          What is Multicast ?
• It is an efficient way of data distribution in
  Internet environment
• It provides the functionality to logically group
  a set of hosts/routers in a distributed fashion
• A class D IP address is used to represent a
  group of receivers
• All the members in a group gets the
  datagram sent by a member
Applications of Multicast ?
                          Distance Learning

                              A scene from the famous network
Multimedia conferencing        game “Shrine of the Ancient”
 Challenges Faced by Multicast
• lack of an elegant protocol
• Existing unicast infrastructure
How did the Multicast started?

The concept of Multicast originated from the “Std IP
Multicast Model” described by Stephen Deering in 1988
Deering’s IP Multicast Model
Deering’s Model explains how the end
systems are to send and receive the multicast
The main features of Deering’s Model are:
1) IP-Style Sematics
2) Open Groups
3) Dynamic Groups
     Deficiencies of Deering’s
          Multicast Model

• Does not discuss how the network should
  perform routing
• No mechanism for providing quality of
  service, security or address allocation
    Virtual Internet Backbone for
        Multicast IP or MBone

• MBone is a virtual network based on Deering’s IP
  Multicast model
• It is layered on top of the physical Internet to support
  routing of IP multicast packets since that function has
  not yet been integrated into many routers
• It is an experiment to upgrade the Internet to handle live
  multimedia messages
• The first MBone network was established in 1992 at the
  Internet Engineering Task Force (IETF) meeting in San
       The Structure of MBone

• The Structure of MBone is based around the use of IP
  Multicast protocol and the use of tunnels
• At the moment, sections of the MBone form a virtual network
  of "islands", interconnected using tunnels over the physical
• Each tunnel connect two end points by one logical link, but
  could cross several Internet routers
• The tunnel endpoints are typically workstation-class machines
  having operating system support for IP multicast and running
  the daemon process "mrouted"
        Topology of MBone
• gross topology of the MBone in May of 1994
     Virtual Internet Backbone for
         Multicast IP or MBone
•   Transmission of Multicast packets through the ordinary routers.

              Encapsulating Multicast packet in normal IP Datagram
   Protocols Used by MBone
• DVMRP (Distance Vector Multicast Routing Protocol)

“Multicast Routing in MBone was a controlled form of flooding”
         Virtual Internet Backbone for
             Multicast IP or MBone

    Following graph shows the growth rate in the number
    of MBone sites

More than 200 sites within the
first year of starting MBone
Deficiencies of MBone

         • It uses only dense mode
           -not efficient if there are
           only a few group
  Intra-domain Multicast Routing is
• Why did Intra-domain Multicasting originated ?
   -tremendous growth in MBone since 1992
   -new multicast method for satisfying the
      increasing number of sites
• What are the features of Intra-domain Multicasting ?
   -sites added to groups called Domains
   -Two more dense mode protocols deployed
      1) Multicast Extensions to OSPF(MOSPF)
      2) Protocol Independent Multicast Dense
         Mode (PIM-DM)
           Features of Intra-domain
• “Sparse mode” protocols created
   -features of Sparse mode
• Two sparse mode protocols
   1)Core Based Trees (CBT) protocols
   2)Protocol Independent Multicast -Sparse Mode (PIM-SM)
        -Rendezvous Point (RP)
• New applications were created
Evolution of Inter-Domain Multicast
• With intra-domain multicasting the
  communication was limited to a domain
• Inter-Domain Multicast considers about
  the communication within a domain and
  between different domains
• It uses Protocols like..
  1) Multicast Border Gateway Protocols
  2) Multicast Source Discovery Protocol
        Inter-domain Multicast

Deployment in Commodity Internet

 -main challenge was to deal with the existing MBone network
 -MBone use tunnels to connect the sites
 -the solution was to put MBone as a separate AS called
 -connectivity between AS10888 and other multicast capable
  AS’s was provided at the NASA Multicast friendly Internet
  eXchange (NASA MIX)
             Inter-domain Multicast
Deployment in Internet2
• The deployment was based on the guidelines set by the
    Internet2 Multicast working group
• The main task was to deploy the Inter-domain Multicast in the
    two backbones
1) vBNS
  -Since the start in 1995 ,was using dense mode protocols
  -due to the severe data flooding problems in 1998 decided to use
    protocols PIM-Sparse Mode,MBGP and MSDP
  -in 1999 became a complete inter-domain multicast backbone
2) Abeline
 -Started only in 1999, so the transition to Inter-domain Multicast
    was an easy process
             Future of Multicast

• Future of Multicast is rooted in the
  continued development, evaluation
  and standardization of new
  protocols and issues like address
  allocation and management
                      Web References

http://www.serpentine.com/~bo   http://www-
s/tech/mbone/                   mice.cs.ucl.ac.uk/multimedia/pr

http://www.webopedia.com/TER    http://nextinet.ncsa.uiuc.edu/nex
M/M/Mbone.html                  tnet/ngi/applications/videoconfe
Types of Multicast
         •   Separate Unicast transport connection to each of
             the receivers
         •   Involves only senders in sending the data
         •   Requires explicit multicast support from the
             network layer

         Application-level multicast
         •    Involves receivers also in the replication and
              forwarding of data
         •    Sender transmits a copy to a smaller number of
              receivers, which then make copies themselves
              and forwards to the other receivers
         •    Significant amount of infrastructure required to
              maintain application level distribution architecture

         Explicit multicast
         •    Single datagram is sent from the sending host and
              gets replicated at a network router whenever it must
              be forwarded on multiple outgoing links to reach the

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