Transcript Evolution of Multicasting

The Evolution of Multicast
Research paper presented by
Ajith M Jose (u4083453)
The Evolution of Multicast
This presentation discusses about:
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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
1992
Multicast Backbone (MBone)
1994
Intra-Domain Multicast
1997
Inter-Domain Multicast
Single flat
topology
Hierarchical
topology
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
Multimedia conferencing
A scene from the famous network
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
packets
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
Diego
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
Internet
• 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
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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)
-broadcast-and-prune
“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
protocols
-not efficient if there are
only a few group
members
Intra-domain Multicast Routing is
Evolving
• 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
Multicasting
• “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
(MBGP)
2) Multicast Source Discovery Protocol
(MSDP)
Inter-domain Multicast
Deployment
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
AS10888
-connectivity between AS10888 and other multicast capable
AS’s was provided at the NASA Multicast friendly Internet
eXchange (NASA MIX)
Inter-domain Multicast
Deployment
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
s/tech/mbone/
http://wwwmice.cs.ucl.ac.uk/multimedia/pr
ojects/mice/mbone_review.html
http://www.webopedia.com/TER
M/M/Mbone.html
http://nextinet.ncsa.uiuc.edu/nex
tnet/ngi/applications/videoconfe
rencing/mbone.html
Types of Multicast
One-to-all
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Separate Unicast transport connection to each of
the receivers
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Involves only senders in sending the data
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Requires explicit multicast support from the
network layer
Application-level multicast
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Involves receivers also in the replication and
forwarding of data
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Sender transmits a copy to a smaller number of
receivers, which then make copies themselves
and forwards to the other receivers
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Significant amount of infrastructure required to
maintain application level distribution architecture
Explicit multicast
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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
receivers