IP Multicasting

1. IP Multicasting
Rumesh Eranga Hapuarachchi
rehrumesh@Hotmail.com

2. Overview
• What is multicast
• Components of Multicast service
• Addressing & groups
• Routing protocols

3. • IP Multicast is a bandwidth-conserving
technology that reduces traffic by simultaneously
delivering a single stream of information to
thousands of corporate recipients and homes.
What is
multicast?

4. • Three main components
• IP Multicast Addressing
• IP Group Management
• Multicast routing
Components

5. • Groups are identified by IP Address range
class D address
• No Access Control
• Sender can be out side of the group
• Less Security
• Unreliable
Multicast
Addressing

6. • Set of receivers for a multicast transmission
• Group identified by the Multicast Address
• To receive multicast transmissions, User must join
and become a member of a group.
Multicast
Groups

7. • Internet Group Management Protocol (IGMP)
• Protocol Independent Multicast Sparse Mode
(PIM-SM).
• Protocol Independent Multicast Dense Mode
(PIM-DM).
• Distance Vector Multicast Routing Protocol
(DVMRP).
• Bi-directional PIM (BIDIR-PIM).
Multicast
Routing
Protocols

8. • Interested receivers send Membership-Report to
nearest multicast router
• Upon receiving Membership-Report Multicast
Router starts sending traffic to that subnet
• Router periodically send MembershipInternet Group
Management
Protocol (IGMP)

9. • There are few most important properties
• Whether they use opt-in or opt-out routing
protocols.
• Whether they use source-based or shared trees.
• The methods they use to find the upstream
router.
Properties of
Routing protocol

10. Opt In Protocol

11. Opt out Protocol

12. Source Based
Tree Protocol
• Source based tree protocol build a separate tree
for each source that send data to multicast group.
• Router wishing to join the multicast group must
specify both the source and the group of the
multicast data.
• The advantage of sourced based tree protocol are
that multicast data path are always efficient and
they benefit from a simpler configuration.

13. Source Based
Tree Protocol

14. Shared Based
Tree Protocol
• Shared tree protocol build a single tree is used for
all source for a multicast group.
• The tree is rooted at some selected node called
rendezvous point.
• The root of each shared multicast tree must be
selected in some manner such as pre
configuration.

15. Shared Based
Tree Protocol

16. PIM- Spare
Mode
• PIM-SM is opt-in multicast routing protocol.
• PIM-SM by default used shared based trees with
the trees rooted at a router called Rendezvous
point (RP) for a group.
• Data is send to an (RP) via encapsulation in PIM
control message sent by unicast.

17. PIM- Dense
Mode
• PIM-DM is opt-out multicast routing protocol.
• PIM-DM uses source-based trees to distribute
data.
• It assumes that the receivers for any multicast
group are distributed densely.
• Links on which the data is not required are
removed from the tree using PIM Prune
messages.
• PIM-DM support source based tree.

18. • 3 main components in IP Multicasting
• Multicast addressing, pros and cons
• What are multicast groups and identification
• Routing protocols
• IGMP 1,2,3
• PIM-SM
• PIM-DM
• DVMRP
• BIDIR-PIM
Summery

19. References
• Wikipedia. “IP multicast” wikipedia.com [Online]. Available :
http://en.wikipedia.org/wiki/IP_multicast
• The Linux Documentation Project . “Multicast Explained”
tldp.com [Online]. Available :
http://www.tldp.org/HOWTO/Multicast-HOWTO-2.html
• Chuck Semeria and Tom Maufer (2013, Aug.
13). “Introduction to IP Multicast Routin”. NC States
University [Online]. Available:
www4.ncsu.edu/~rhee/clas/csc495j/ip-multicast-part1.pdf