Ipmulticasting
Download as PPTX, PDF0 likes588 views
The document outlines the key components of IP multicasting including multicast addressing, groups, routing protocols, and properties of routing protocols. It discusses Internet Group Management Protocol (IGMP) and its role in allowing hosts to join and leave multicast groups. The document also explains the differences between opt-in and opt-out routing protocols, source-based and shared trees, and dense and sparse modes such as PIM-Dense Mode and PIM-Sparse Mode.
Ipmulticasting
- 2. Presentation Outline • Introduction about IP Multicasting • Component of Multicast service • Multicast Addressing • Multicast Groups • Multicast Routing Protocol • Internet Group Management Protocol (IGMP) • Properties of Routing Protocol • Difference between OPT-IN & OPT-OUT Protocol • Source Based Tree protocol • Shared Based Tree • PIM-Spare Mode • PIM-Dense Mode
- 3. Introduction Multicast communications refers to one-to-many or many-to-many communications. three fundamental types of IPv4 addresses Unicast Broadcast Multicast
- 4. What is Multicast? • A multicast is similar to a broadcast in the sense that its target is a number of machines on a network, but not all • a multicast is directed to a group of hosts • The hosts can choose whether they wish to participate in the multicast group
- 5. Component of Multicast service There are three essential components of the IP Multicast service: IP Multicast Addressing IP Group Management Multicast Routing
- 6. Multicast Addressing Multicast groups are identified by IP addresses in the range 224.0.0.0 - 239.255.255.255 (class D address) Every host (more precisely: interface) can join and leave a multicast group dynamically • no access control Every IP datagram send to a multicast group is transmitted to all members of the group • no security • Sender does not need to be a member of the group The IP Multicast service is unreliable . . . IP Multicasting only supports UDP as higher layer There is no multicast TCP ! Class From To D 224.0.0.0 239.255.255.255
- 7. Multicast Groups • The set of receivers for a multicast transmission is called a multicast group. Key concepts in IP multicast include an IP multicast group address A multicast group is identified by a multicast address A user that wants to receive multicast transmissions joins the corresponding multicast group, and becomes a member of that group. • After a user joins, the network builds the necessary routing paths so that the user receives the data sent to the multicast group
- 8. Multicast Routing Protocol 1) Internet Group Management Protocol (IGMP) 2) Protocol Independent Multicast Sparse Mode (PIM-SM). 3) Protocol Independent Multicast Dense Mode (PIM-DM). 4) Distance Vector Multicast Routing Protocol (DVMRP). 5) Bi-directional PIM (BIDIR-PIM).
- 9. Internet Group Management Protocol (IGMP) IGMP provides three basic functions for IP multicast networks: • JOIN: An IGMP host indicates that it wants to receive information from (“become a member of”) a multicast group. • LEAVE: An IGMP host indicates that it no longer wishes to receive information from a multicast group. • QUERY: An IGMP router can ask the hosts which groups they are members of. This is done to verify a JOIN/LEAVE request or to look for error conditions. There are 3 version of IGMP 1) IGMPv1:- Hosts can join multicast groups. There were no leave messages. Routers were using a time-out based mechanism to discover the groups that are of no interest to the members. 2) IGMPv2:- Leave messages were added to the protocol. Allow group membership termination to be quickly reported to the routing protocol, which is important for high- bandwidth multicast groups. 3) IGMPv3:- Major revision of the protocol. It allows hosts to specify the list of hosts from which they want to receive traffic from
- 10. Properties of Routing Protocol Four of the most important features of multicast routing protocols are the following. • 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.
- 11. Difference between OPT-IN & OPT-OUT Protocol Opt-in Protocols: Opt-in or sparse protocols are designed on the assumption that most subnets in the network will not want any given multicast packet
- 12. Difference between OPT-IN & OPT-OUT Protocol In opt-out or broadcast-and-prune or dense protocols, it is initially assumed that every router on the network wishes to receive multicast data, and data is sent to all routers. Routers wishing to remove themselves from the multicast tree must then send a Prune message to the upstream router.
- 13. Source Based Tree protocol1) Source based tree protocol build a separate tree for each source that send data to multicast group. 2) Router wishing to join the multicast group must specify both the source and the group of the multicast data. 3) The advantage of sourced based tree protocol are that multicast data path are always efficient and they benefit from a simpler configuration.
- 14. Shared Based Tree1) Shared tree protocol build a single tree is used for all source for a multicast group. 2) The tree is rooted at some selected node called rendezvous point. 3) The root of each shared multicast tree must be selected in some manner such as pre - configuration.
- 15. PIM-Spare Mode1) PIM-SM is opt-in multicast routing protocol. 2) PIM-SM by default used shared based trees with the trees rooted at a router called Rendezvous point (RP) for a group. 3) Data is send to an (RP) via encapsulation in PIM control message sent by unicast.
- 16. PIM-Dense Mode 1) PIM-DM is opt-out multicast routing protocol. 2) PIM-DM uses source-based trees to distribute data. 3) It assumes that the receivers for any multicast group are distributed densely. 4) Links on which the data is not required are removed from the tree using PIM Prune messages. 5) PIM-DM support source based tree.
- 18. Thank You
Editor's Notes
- #5: Where a broadcast is directed to all hosts on the network, a multicast is directed to a group of hosts. The hosts can choose whether they wish to participate in the multicast group (often done with the Internet Group Management Protocol), whereas in a broadcast, all hosts are part of the broadcast group whether they like it or not!
- #7: Host Extensions for IP Multicasting [RFC1112] specifies the extensions required of a host implementation of the Internet Protocol (IP) to support multicasting. The multicast addresses are in the range 224.0.0.0 through 239.255.255.255. Address assignments are listed below. The range of addresses between 224.0.0.0 and 224.0.0.255, inclusive, is reserved for the use of routing protocols and other low-level topology discovery or maintenance protocols, such as gateway discovery and group membership reporting. Multicast routers should not forward any multicast datagram with destination addresses in this range, regardless of its TTL.
- #8: An IP multicast group address is used by sources and the receivers to send and receive multicast messages. Sources use the group address as the IP destination address in their data packets. Receivers use this group address to inform the network that they are interested in receiving packets sent to that group.
- #9: With routing protocols based on shared trees, once the receivers join a particular IP multicast group, a multicast distribution tree is constructed for that group. The protocol most widely used for this is Protocol Independent Multicast (PIM). It sets up multicast distribution trees such that data packets from senders to a multicast group reach all receivers which have joined the group
- #10: On the local network, multicast delivery is controlled by IGMP (on IPv4 network) and MLD (on IPv6 network); inside a routing domain, PIM or MOSPF are used; between routing domains, one uses inter-domain multicast routing protocols, such as MBGP.