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© 1999, Cisco Systems, Inc. 9-1 Chapter 10 Controlling Campus Device Access Chapter 9 Multicast Overview © 1999, Cisco Systems, Inc. 10-1.

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Presentation on theme: "© 1999, Cisco Systems, Inc. 9-1 Chapter 10 Controlling Campus Device Access Chapter 9 Multicast Overview © 1999, Cisco Systems, Inc. 10-1."— Presentation transcript:

1 © 1999, Cisco Systems, Inc. 9-1 Chapter 10 Controlling Campus Device Access Chapter 9 Multicast Overview © 1999, Cisco Systems, Inc. 10-1

2 © 1999, Cisco Systems, Inc. BCMSN9-2 Objectives Upon completion of this chapter, you will be able to perform the following tasks: Match the correct transmission method to the appropriate definition Reconcile a set of IP multicast addresses to Ethernet addresses Describe the functional differences between IGMPv1 and IGMPv2 Describe the setup procedure in which routers and switches facilitate multicast traffic Identify the appropriate multicast routing protocol for a given network requirement

3 © 1999, Cisco Systems, Inc. BCMSN9-3 Multicast Overview Multicast overview Addressing in a multicast environment Managing multicast traffic in a campus network Routing multicast traffic Multicast routing protocols In this chapter, we discuss the following topics :

4 © 1999, Cisco Systems, Inc. BCMSN9-4 Multicast Overview In this section, we discuss the following topics: Multicast Overview –Unicast Traffic –Broadcast Traffic –Multicast Traffic –IP Multicast Characteristics Addressing in a Multicast Environment Managing Multicast Traffic in a Campus Network Routing Multicast Traffic Multicast Routing Protocols

5 © 1999, Cisco Systems, Inc. BCMSN9-5 Unicast Traffic Video Server Receiver Not A Receiver Unicast applications send one copy of each packet to every client unicast address

6 © 1999, Cisco Systems, Inc. BCMSN Mb x 3 = 4.5 Mb 1.5 Mb x 2 = 3 Mb1.5 Mb x 1 = 1.5 Mb Unicast Traffic (cont.) Video Server Receiver Not A Receiver

7 © 1999, Cisco Systems, Inc. BCMSN9-7 Unicast Traffic (cont.) Mb x 100 = 150 Mb Receiver 1Receiver Mb x 100 = 150 Mb Video Server

8 © 1999, Cisco Systems, Inc. BCMSN9-8 Broadcast Traffic I dont want to receive this video stream, but my CPU still needs to process that 1.5 MB of data! 1.5 Mb Video Server Receiver Not A Receiver Hosts not using a multimedia application must still process the broadcast traffic

9 © 1999, Cisco Systems, Inc. BCMSN9-9 Multicast Traffic 1.5 Mb Video Server Receiver Not A Receiver A multicast server sends out a single data stream to multiple clients using a special broadcast address

10 © 1999, Cisco Systems, Inc. BCMSN9-10 IP Multicast Characteristics Transmits to a host group Delivers with best effort reliability Supports dynamic membership Supports diverse numbers and locations Supports membership in more than one group Supports multiple streams host

11 © 1999, Cisco Systems, Inc. BCMSN9-11 IP Multicast Characteristic (text cont.)

12 © 1999, Cisco Systems, Inc. BCMSN9-12 Multicast Overview In this section, we discuss the following topics: Multicast Overview Addressing in a Multicast Environment –IP Multicasting Address Structure –Mapping MAC addresses to IP Multicast Addresses Managing Multicast Traffic in a Campus Network Routing Multicast Traffic Multicast Routing Protocols

13 © 1999, Cisco Systems, Inc. BCMSN9-13 Multicast IP Address Structure A Class D address consists of 1110 as the higher order bits in the first octet, followed by a 28-bit group address. Class D addresses range from through The high-order bits in the first octet identify this 224-base address. Multicast Group ID1101Class D 28 bits

14 © 1999, Cisco Systems, Inc. BCMSN9-14 Mapping IP Multicast to Ethernet Addresses Class D IP Address 48-Bit Ethernet Address Not Used Low-Order 23 Bits of Multi-cast Group ID Copied to Ethernet Address E 224

15 © 1999, Cisco Systems, Inc. BCMSN Multicast Address: Ethernet Address: Mapping Multicast to Ethernet Addresses: Example 1 5E0A

16 © 1999, Cisco Systems, Inc. BCMSN9-16 Mapping Multicast to Ethernet Addresses: Example Multicast Address: Ethernet Address: 5E0A

17 © 1999, Cisco Systems, Inc. BCMSN9-17 Multicast Overview In this section, we discuss the following topics: Multicast Overview Addressing in a Multicast Environment Managing Multicast Traffic in a Campus Network –Subscribing and Maintaining Groups –IGMPv1 –IGMPv2 –Handling Multicast Traffic in the Switch Routing Multicast Traffic Multicast Routing Protocols

18 © 1999, Cisco Systems, Inc. BCMSN9-18 Facilitating Multimedia Traffic Coordinate multicast operations of network devices Establish a path between between source and destination Forward multicast traffic through the network Source Destination

19 © 1999, Cisco Systems, Inc. BCMSN9-19 Group Membership Host A Host BHost C Host D Im not a member so I wont respond. Im a member so I will respond. Are there any members for Group XYZ? Multicast uses query and report messages to establish and maintain group membership

20 © 1999, Cisco Systems, Inc. BCMSN9-20 IGMPv1Packet Format Version Code Version = 1 Type: – 1 = Host Membership Query – 2 = Host Membership Report Group Address: – Multicast Group Address VerUnused Checksum Type 4 Group Address

21 © 1999, Cisco Systems, Inc. BCMSN9-21 IGMPv1Joining a Group Joining member sends report to immediately upon joining H Report IGMPv1 H1H2

22 © 1999, Cisco Systems, Inc. BCMSN9-22 IGMPv1General Queries The router periodically sends general queries to to determine memberships General Query to IGMPv1 Multicast Router H3H1H2

23 © 1999, Cisco Systems, Inc. BCMSN9-23 IGMPv1Maintaining a Group IGMPv1#1 Router sends periodic queries #2 One member per group per subnet report #2#3 Other members suppress reports X #3 H3H1H2 Query to #1 Report Suppressed

24 © 1999, Cisco Systems, Inc. BCMSN9-24 Router sends periodic queries Hosts silently leave group Router continues sending periodic queries Query to IGMPv1Leaving a Group IGMPv1 No reports for group received by router Group times out H3H1H2

25 © 1999, Cisco Systems, Inc. BCMSN9-25 IGMPv2Packet Format Multiple message types Max. Resp. Time – Max. time before sending a responding report in 1/10 secs (default = 10 secs) Group Address: – Multicast Group Address ( for General Queries) Max. Resp. TimeChecksum Group Address Type 71531

26 © 1999, Cisco Systems, Inc. BCMSN9-26 IGMPv2Joining a Group Joining member sends report to immediately upon joining (same as IGMPv1) Report H RTR141 H3 H2

27 © 1999, Cisco Systems, Inc. BCMSN9-27 IGMPv2Joining a Group (cont.) H RTR141 E0 H2H3 RTR141>show ip igmp group IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter Ethernet0 6d17h 00:02:

28 © 1999, Cisco Systems, Inc. BCMSN9-28 IGMPv2Querier Election Intially all routers send out a query Router with lowest IP address elected querier Other routers become non-queriers IGMPv2 H1 H2H3 Query IGMP Querier IGMP Non-Querier

29 © 1999, Cisco Systems, Inc. BCMSN9-29 Querier Election (Text Only)

30 © 1999, Cisco Systems, Inc. BCMSN9-30 IGMPv2Querier Election Locating the designated querier router RTR141>show ip igmp interface e0 Ethernet0 is up, line protocol is up Internet address is , subnet mask is IGMP is enabled on interface Current IGMP version is 2 CGMP is disabled on interface IGMP query interval is 60 seconds IGMP querier timeout is 120 seconds IGMP max query response time is 10 seconds Inbound IGMP access group is not set Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is (this system) IGMP querying router is (this system) Multicast groups joined:

31 © 1999, Cisco Systems, Inc. BCMSN9-31 IGMPv2Maintaining a Group Router sends periodic queries Query IGMPv2 One member per group per subnet report Report Other members suppress reports Suppressed X H2 H H1

32 © 1999, Cisco Systems, Inc. BCMSN9-32 IGMPv2Leaving a Group H1 H2 H3 RTR141 IGMP state in RTR141 before leave RTR141>sh ip igmp group IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter Ethernet0 6d17h 00:02:

33 © 1999, Cisco Systems, Inc. BCMSN9-33 IGMPv2Leaving a Group (cont.) H2 leaves group; sends leave message H1 H2 H3 H2 Leave to #1 Router sends group-specific query Group Specific Query to #2 A remaining member host sends report; Report to #3 group remains active RTR #1 #2 #3

34 © 1999, Cisco Systems, Inc. BCMSN9-34 Leaving a Group (Text Only)

35 © 1999, Cisco Systems, Inc. BCMSN9-35 IGMPv2Leaving a Group (cont.) H1 H2H3 RTR141 IGMP state in RTR141 after H2 leaves RTR141>sh ip igmp group IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter Ethernet0 6d17h 00:01:

36 © 1999, Cisco Systems, Inc. BCMSN9-36 IGMPv2Leaving a Group (Cont.) Last host leaves group; sends Leave message H1 H3 Leave to #1 Router sends group-specific query; Group-specific Query to #2 no report is received, group times out H2#1 #2 RTR

37 © 1999, Cisco Systems, Inc. BCMSN9-37 IGMPv2Leaving a Group (cont.) RTR141>sh ip igmp group IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter H1 H2 RTR141 IGMP state in RTR141 after H3 leaves H3

38 © 1999, Cisco Systems, Inc. BCMSN9-38 Multicast Overview In this section, we discuss the following topics: Multicast Overview Addressing in a Multicast Environment Managing Multicast Traffic in a Campus Network Routing –GCMP Routing Multicast Traffic Multicast Routing Protocols

39 © 1999, Cisco Systems, Inc. BCMSN9-39 Layer 2 Multicast I dont want to receive this video stream, but my CPU still needs to process that 1.5 MB of data! 1.5 Mb Receiver Not A Receiver Video Server

40 © 1999, Cisco Systems, Inc. BCMSN9-40 CGMP c IGMP Join Request c would like to join multicast group XYZ c would like to join multicast group XYZ. CGMP is a Cisco-developed protocol CGMP allows Catalyst switches to learn about the existence of multicast clients from Cisco routers

41 © 1999, Cisco Systems, Inc. BCMSN9-41 CGMP (cont.) Device c wants to join Group Device c wants to join Group CGMP Message c CGMP Message I have no knowledge of device c I have no knowledge of device c I can reach device c out of Port 1. I will add to my switch forwarding table.

42 © 1999, Cisco Systems, Inc. BCMSN9-42 Multicast Overview In this section, we discuss the following topics: Multicast Overview Addressing in a Multicast Environment Managing Multicast Traffic in a Campus Network Routing Multicast Traffic –Routing Protocols –Distribution Trees –Scope of Delivery Multicast Routing Protocols

43 © 1999, Cisco Systems, Inc. BCMSN9-43 Unicast Routing Host A Network Network Server B Destination Address Source Address

44 © 1999, Cisco Systems, Inc. BCMSN9-44 Multicast Routing Host A Host B Network Network Network B I dont have any clients in group but Router B has. I dont have any clients in group but Router B has. A e Multimedia Stream for Group XYZ

45 © 1999, Cisco Systems, Inc. BCMSN9-45 Distribution Trees I am a member of Group XYZ. I am a member of Group XYZ. I am a member of Group XYZ. I am a member of Group XYZ. I am NOT member of Group XYZ. I am NOT member of Group XYZ. Packet Duplication at This Point Only

46 © 1999, Cisco Systems, Inc. BCMSN9-46 Distribution Trees (Text Only) I am a member of Group XYZ. I am a member of Group XYZ. I am a member of Group XYZ. I am a member of Group XYZ. I am NOT member of Group XYZ. I am NOT member of Group XYZ. Packet Duplication at this point only

47 © 1999, Cisco Systems, Inc. BCMSN9-47 Source Distribution Tree Server 1 Group ABC Host 1 Group ABC ABCDEFG Source-specific trees use the shortest path from the sender to each receiver Host 2 Group ABC Host 3 Group ABC

48 © 1999, Cisco Systems, Inc. BCMSN9-48 Source Distribution Tree (cont.) Server 1 Group ABC Host 1 Group ABC ABCDEFG Host 2 Group ABC If the link between the local router and the neighboring router is not the shortest path, the packet is not forwarded on that link

49 © 1999, Cisco Systems, Inc. BCMSN9-49 Shared Distribution Tree Source 1 ABCDEFG Source 2 Multicast traffic for each group is sent and received over the same delivery tree, regardless of the source

50 © 1999, Cisco Systems, Inc. BCMSN9-50 Shared Distribution Tree (Text Cont.)

51 © 1999, Cisco Systems, Inc. BCMSN9-51 Scope of Delivery Acme Manufacturing, Inc. Human Resources Engineering PersonnelPayroll TTL Threshold = 15 TTL Threshold = 31 TTL Threshold = 127 Assigning a TTL threshold to each interface limits the scope of multicast transmission

52 © 1999, Cisco Systems, Inc. BCMSN9-52 Time To Live Threshold E0 E1 E2 E3 E1: (TTL Threshold = 16) E2: (TTL Threshold = 0) E3: (TTL Threshold = 64) Multicast Packet w/TTL=24 Packet Not Forwarded!

53 © 1999, Cisco Systems, Inc. BCMSN9-53 Multicast Overview In this section, we discuss the following topics: Multicast Overview Addressing in a Multicast Environment Managing Multicast Traffic in a Campus Network Routing Multicast Traffic Multicast Routing Protocols –Dense Mode Routing Protocols –Sparse Mode Routing Protocols

54 © 1999, Cisco Systems, Inc. BCMSN9-54 Dense Mode Routing Protocols Densely distributed receivers Plentiful bandwidth Majority of routers forwarding multicast traffic Protocols – DVMRP – MOSPF – PIM DM

55 © 1999, Cisco Systems, Inc. BCMSN9-55 Dense Mode Routing Protocols (Text Only)

56 © 1999, Cisco Systems, Inc. BCMSN9-56 Distance Vector Multicast Routing Protocol This is a multicast packet for Group XYZ. This is a multicast packet for Group XYZ. Reverse path flooding floods a packet on all paths except the path leading back to the source.

57 © 1999, Cisco Systems, Inc. BCMSN9-57 Multicast Open Shortest Path First (MOSPF) I have a new member for Group XYZ. I have a new member for Group XYZ. Source 1 Group XYZ ABCDEFG Designated Router Router F has a new member for Group XYZ. Router F has a new member for Group XYZ. Uses OSPF link-state advertisements to construct distribution trees Trees must be recomputed when a link-state change occurs

58 © 1999, Cisco Systems, Inc. BCMSN9-58 Protocol Independent Multicast Dense Mode (PIM DM) This is a multicast packet for Group XYZ. This is a multicast packet for Group XYZ. Protocol-independent means the protocol is not dependent on any unicast routing protocol I have no members for Group XYZ. I have no members for Group XYZ. Prune Message

59 © 1999, Cisco Systems, Inc. BCMSN9-59 PIM-DM (Text Cont.)

60 © 1999, Cisco Systems, Inc. BCMSN9-60 Sparse-Mode Routing Protocols Sparsely distributed receivers Limited bandwidth Add branches as a result of explicit joins Protocols – CBT – PIM SM

61 © 1999, Cisco Systems, Inc. BCMSN9-61 Core-Based Tree Core Router I have a member who wants to join Group XYZ. I have a member who wants to join Group XYZ. ABCDE Join Message Source 1 Join Message Source 2 CBT protocol constructs a single tree shared by all members of the group A CBT shared tree has a core router that is used to construct the tree I am already a branch of that tree. I will acknowledge the join message. I am already a branch of that tree. I will acknowledge the join message.

62 © 1999, Cisco Systems, Inc. BCMSN9-62 Protocol Independent Multicast Sparse Mode (PIM SM) Rendezvous Point I want to start receiving multicast packets to Group XYZ I want to start receiving multicast packets to Group XYZ ACBD Optimized Path Initial Path Initial Path I want to start sending multicast packets to Group XYZ I want to start sending multicast packets to Group XYZ Initial Path

63 © 1999, Cisco Systems, Inc. BCMSN9-63 PIM-SM (Text Only)

64 © 1999, Cisco Systems, Inc. BCMSN9-64 Written Exercise Following is the written exercise for this chapter

65 © 1999, Cisco Systems, Inc. BCMSN9-65 Summary Multicast is the most efficient method for data transmission to multiple client. IP Multicast employs special addressing. IGMP allows clients to join and leave multicast groups. CGMP allows switches to handle multicast traffic. Special routing protocols are used to route multicast traffic through the network. Multicast routing protocols are divided into two categories.

66 © 1999, Cisco Systems, Inc. BCMSN9-66 Review Discuss the three types of transmission methods and the effect each one has on network bandwidth. Explain how routers and switches handle the impact of multicast addressing techniques. Discuss different multicast routing protocols and identify which ones are most effective in a campus network.

67 © 1999, Cisco Systems, Inc. BCMSN9-67 Review (text cont.)

68 © 1999, Cisco Systems, Inc. BCMSN9-68 Review (text cont.)


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