© 2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialBSCI 1 BSCI Module 7 Lesson 3 Multicast Routing Protocols IP Multicasting © 2008 Cisco Systems, Inc. All rights reserved.BSCI 2 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Objectives Describe a multicast network in terms of the IP multicast routing protocols and processes used over various segments. Describe multicast distribution trees including source trees and shared trees. Describe the (S,G) and (*,G) multicast distribution trees entry formats. Explain IP multicast routing. Identify the characteristics of each of the PIM modes. Describe the operation of PIM-DM, PIM-SM, and PIM sparse-dense modes. © 2008 Cisco Systems, Inc. All rights reserved.BSCI 3 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Multicast Distribution Trees © 2008 Cisco Systems, Inc. All rights reserved.BSCI 4 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Multicast Protocol Basics Types of multicast distribution trees: Source distribution trees; also called shortest path trees (SPTs) – With a source tree, a separate tree is built for each source to all members of its group. – For groups that have a very large number of sources, or networks that have a very large number of groups with a large number of sources in each group, source trees can stress the storage capability of routers. Shared distribution trees; rooted at a meeting point in the network – A core router serves as a rendezvous point (RP) © 2008 Cisco Systems, Inc. All rights reserved.BSCI 5 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Shortest Path or Source Distribution Tree Receiver 1 B E A D F Source 1 Notation: (S, G) S = Source G = Group C Receiver 2 Source 2 Multicast Distribution Trees © 2008 Cisco Systems, Inc. All rights reserved.BSCI 6 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Receiver 1 B E A D F Source 1 Notation: (S, G) S = Source G = Group C Receiver 2 Source 2 Multicast Distribution Trees Shortest Path or Source Distribution Tree © 2008 Cisco Systems, Inc. All rights reserved.BSCI 7 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Multicast Distribution Trees Receiver 1 B E A D F Notation: (*, G) * = All Sources G = Group C Receiver 2 (RP) PIM Rendezvous Point Shared Tree (RP) Shared Distribution Tree © 2008 Cisco Systems, Inc. All rights reserved.BSCI 8 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Multicast Distribution Trees Receiver 1 B E A F Source 1 Notation: (*, G) * = All Sources G = Group C Receiver 2 Source 2 (RP) PIM Rendezvous Point Shared Tree Source Tree D (RP) Shared Distribution Tree © 2008 Cisco Systems, Inc. All rights reserved.BSCI 9 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Multicast Distribution Tree Identification (S,G) entries For this particular source sending to this particular group Traffic is forwarded through the shortest path from the source (*,G) entries For any (*) source sending to this group Traffic is forwarded through a meeting point for this group © 2008 Cisco Systems, Inc. All rights reserved.BSCI 10 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com Multicast Distribution Trees Characteristics of Distribution Trees Source or Shortest Path trees Uses more memory but optimal paths from source to all receivers; minimizes delay Shared trees Uses less memory but sub-optimal paths from source to all receivers; may introduce extra delay [...]... reserved Học viện mạng Bách Khoa - www.bkacad.com 16 CCNP – BSCI Bachkhoa Networking Academy Multicast Forwarding Multicast routing operation is the opposite of unicast routing Unicast routing is concerned with where the packet is going Multicast routing is concerned with where the packet comes from Multicast routing uses Reverse Path Forwarding (RPF) to prevent forwarding loops BSCI © 2008 Cisco Systems,... Academy Multicast Routing BSCI © 2008 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 12 CCNP – BSCI Bachkhoa Networking Academy IP Multicast Routing In unicast routing, when the router receives the packet, the decision about where to forward the packet depends on the destination address of the packet In multicast routing, the decision about where to forward the multicast. .. from Multicast routing uses a mechanism called Reverse Path Forwarding (RPF) to prevent forwarding loops and to ensure the shortest path from the source to the receivers BSCI © 2008 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 13 CCNP – BSCI Bachkhoa Networking Academy Protocols for IP Multicast Routing PIM is used between routers so that they can track which multicast. .. Bachkhoa Networking Academy Protocol-Independent Multicast (PIM) PIM maintains the current IP multicast service mode of receiver-initiated membership PIM is not dependent on a specific unicast routing protocol With PIM, routers maintain forwarding tables to forward multicast datagrams PIM can operate in dense mode or sparse mode –Dense mode protocols flood multicast traffic to all parts of the network... 21 CCNP – BSCI Bachkhoa Networking Academy Multicast Distribution Tree Creation Shared Tree Example BSCI © 2008 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 22 CCNP – BSCI Bachkhoa Networking Academy Self Check 1 Why is Protocol Independent Multicast called Independent? 2 Describe dense mode operation 3 What does multicast routing use to prevent forwarding loops? 4... Networking Academy Reverse Path Forwarding (RPF) The RPF Calculation The multicast source address is checked against the unicast routing table This determines the interface and upstream router in the direction of the source to which PIM Joins are sent This interface becomes the “Incoming” or RPF interface –A router forwards a multicast datagram only if received on the RPF interface BSCI © 2008 Cisco... unicast routing protocols PIM-SM supports both source and shared trees PIM-SM is based on an explicit pull model PIM-SM uses an RP –Senders and receivers “meet each other.” –Senders are registered with RP by their first-hop router –Receivers are joined to the shared tree (rooted at the RP) by their local DR BSCI © 2008 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 30 ... Học viện mạng Bách Khoa - www.bkacad.com 33 CCNP – BSCI Bachkhoa Networking Academy PIM-SM Sender Registration RP Source Traffic Flow Source traffic flows natively along SPT to RP Shared Tree Source Tree From RP, traffic flows down the Shared Tree to Receivers Receiver BSCI © 2008 Cisco Systems, Inc All rights reserved Học viện mạng Bách Khoa - www.bkacad.com 34 CCNP – BSCI Bachkhoa Networking Academy...CCNP – BSCI Bachkhoa Networking Academy Self Check 1 What is an advantage of Shortest Path Trees compared to Shared Trees? 2 What does multicast use to make it’s forwarding decisions? 3 In the STP notation (S,G), what do each of the characters represent? 4 What is the root of the shared tree called? 5 Compare Shared Distribution trees and SPT trees in terms... reserved Học viện mạng Bách Khoa - www.bkacad.com 26 CCNP – BSCI Bachkhoa Networking Academy PIM-DM Flood and Prune (Cont.) Results After Pruning •In PIM-DM, all prune messages expire in 3 minutes After that, the multicast traffic is flooded again to all of the routers This periodic flood-and-prune behavior is normal and must be taken into account when the network is designed to use PIM-DM BSCI © 2008 . Cisco Systems, Inc. All rights reserved. Cisco ConfidentialBSCI 1 BSCI Module 7 Lesson 3 Multicast Routing Protocols IP Multicasting © 2008 Cisco Systems, Inc. All rights reserved.BSCI 2 CCNP. www.bkacad.com Multicast Forwarding Multicast routing operation is the opposite of unicast routing. Unicast routing is concerned with where the packet is going. Multicast routing is concerned. www.bkacad.com Multicast Routing © 2008 Cisco Systems, Inc. All rights reserved.BSCI 13 CCNP – BSCI Bachkhoa Networking Academy Học viện mạng Bách Khoa - www.bkacad.com IP Multicast Routing