Module 7- Lesson 3 Multicast Routing Protocols potx

© 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 