© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 1 IP Multicasting: Explaining Multicast.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 2 Objectives  Describe the IP multicast group.  Compare and contrast Unicast packets and multicast packets.  List the advantages and disadvantages of multicast traffic.  Discuss two types of multicast applications.  Describe the types of IP multicast addresses.  Describe how receivers can learn about a scheduled multicast session.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 5 Why Multicast?  Used when sending same data to multiple receivers  Better bandwidth utilization  Less host/router processing  Used when addresses of receivers unknown  Used when simultaneous delivery for a group of receivers is required (simulcast)

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 7 Multicast Advantages Enhanced efficiency: Controls network traffic and reduces server and CPU loads Optimized performance: Eliminates traffic redundancy Distributed applications: Makes multipoint applications possible

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 8 Types of Multicast Applications One-to-many  A single host sending to two or more (n) receivers Many-to-many  Any number of hosts sending to the same multicast group; hosts are also members of the group (sender = receiver) Many-to-one  Any number of receivers sending data back to a source (via unicast or multicast)

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 9 Corporate Broadcasts Distance Learning Training Videoconferencing Whiteboard/Collaboration Multicast File Transfer Data and File Replication Real-Time Data Delivery—Financial Video-on-Demand Live TV and Radio Broadcast to the Desktop IP Multicast Applications

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 10 Self Check 1.List some advantages of multicast transmission over unicast transmission. 2.How does the best effort delivery nature of UDP impact multicast transmissions? 3.What are the 3 basic types of multicast applications? 4.Give examples of one-to-many. 5.What model is used when a host can be a sender as well as a receiver simultaneously?

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 12 IP Multicast Address Structure IP group addresses:  Class D address (high-order three bits are set)  Range from 224.0.0.0 through 239.255.255.255

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 13 Multicast Addressing IPv4 Header OptionsPadding Time to LiveProtocolHeader Checksum IdentificationFlagsFragment Offset VersionIHLType of ServiceTotal Length Source Address Destination Address Destination Source Source Address can never be Class D Multicast Group Address 224.0.0.0 - 239.255.255.255 (Class D) Multicast Group Address Range Destination 1.0.0.0 - 223.255.255.255 (Class A, B, C) Source

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 14 IP Multicast Address Groups  Local scope addresses 224.0.0.0 to 224.0.0.255  Global scope addresses 224.0.1.0 to 238.255.255.255  Administratively scoped addresses (private) 239.0.0.0 to 239.255.255.255

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 15 Local Scope Addresses Well-known addresses assigned by IANA  Reserved use: 224.0.0.0 through 224.0.0.255 224.0.0.1 (all multicast clients on subnet) 224.0.0.2 (all routers on subnet) 224.0.0.4 (all DVMRP routers) 224.0.0.13 (all PIMv2 routers) 224.0.0.5, 224.0.0.6, 224.0.0.9, and 224.0.0.10 used by unicast routing protocols

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 16 IANA Ethernet MAC Address Range 01-00-5e-00-00-00 through 01-00-5e-7f-ff-ff Available range of MAC addresses for IP multicast Because the 7 th hexadecimal character is 0 – 7, the 25 th bit will always be 0. 00000001:00000000:01011110:00000000:00000000:00000000

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 17 00000001:00000000:01011110:00000000:00000000:00000000 IANA Ethernet MAC Address Range through  Within this range, these MAC addresses have the first 25 bits in common.  The remaining 23 bits are available for mapping to the lower 23 bits of the IP multicast group address. Available range of MAC addresses for IP multicast 00000001:00000000:01011110:01111111:11111111:11111111

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 19 224.1.1.1 224.129.1.1 225.1.1.1 225.129.1.1. 238.1.1.1 238.129.1.1 239.1.1.1 239.129.1.1 0x0100.5E01.0101 1 - Multicast MAC Address (FDDI and Ethernet) Multicast Addressing Since the only 23 bits of the multicast IP address are used and the first four bits are always 1110, bits 5 – 8 (five bits) are always ignored! This means that there are 32 IP addresses that match any one multicast MAC address!!! Since the only 23 bits of the multicast IP address are used and the first four bits are always 1110, bits 5 – 8 (five bits) are always ignored! This means that there are 32 IP addresses that match any one multicast MAC address!!! 11100000.00000001.00000001.00000001 = 224.1.1.1

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 21 Summary  IP multicast is a much more efficient means of delivering content where a single sender needs to deliver the content to multiple receivers. This task may be achieved through the use of multicast groups.  IP multicasts are designated by the use of a specific Class D IP address range. This is achieved through global scope addresses, which are assigned dynamically, and administratively scoped, which are assigned locally and are reserved for use inside private domains.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 22 Resources  Wikipedia IP Multicast article http://en.wikipedia.org/wiki/IP_Multicast  Webopedia Mbone article http://www.webopedia.com/TERM/M/Mbone.html

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 24 Objectives  Explain the operations of IGMPv2 and how IGMPv2 utilizes Join Group and Leave Group messages.  Explain the operations of IGMPv3 and how IGMPv2 and IGMPv3 interoperate.  Describe the methods used to deal with multicast in a Layer 2 switching environment.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 26 Internet Group Management Protocol (IGMP) How hosts tell routers about group membership  Routers solicit group membership from directly connected hosts RFC 1112 specifies IGMPv1 Supported on Windows 95 RFC 2236 specifies IGMPv2 Supported on latest service pack for Windows and most UNIX systems RFC 3376 specifies IGMPv3 Supported in Window XP and various UNIX systems

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 27 IGMPv2 RFC 2236  Group-specific query Router sends query membership message to a single group rather than all hosts (reduces traffic).  Leave group message Host sends leave message if it leaves the group and is the last member (reduces leave latency in comparison to v1).  Query-interval response time The Query router sets the maximum Query-Response time (controls burstiness and fine-tunes leave latencies).  Querier election process IGMPv2 routers can elect the Query Router without relying on the multicast routing protocol.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 28 IGMPv3  IGMPv3 adds the ability to filter multicasts based on the multicast source.  IGMPv3 allows hosts to indicate that they want to receive traffic only from particular sources within a multicast group.  IGMPv3 is the industry-designated standard protocol for hosts to signal channel subscriptions in Source Specific Multicast (SSM). http://www.cisco.com/en/US/products/sw/iosswrel/ps1834/products_feature_guide09186a0080080515.html

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 29 IGMPv3 (cont.)  IGMPv3 runs in two modes: INCLUDE and EXCLUDE  INCLUDE mode—In this mode, the receiver announces membership to a host group and provides a list of IP addresses (the INCLUDE list) from which it wants to receive traffic.  EXCLUDE mode—In this mode, the receiver announces membership to a host group and provides a list of IP addresses (the EXCLUDE list) from which it does not want to receive traffic. This indicates that the host wants to receive traffic only from other sources whose IP addresses are not listed in the EXCLUDE list.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 38 IGMPv3—Joining Specific Source(s) IGMPv3 Report contains desired sources in the Include list. Only “Included” sources are joined.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 39 IGMPv3—Maintaining State Router sends periodic queries:  All IGMPv3 members respond. Reports contain multiple group state records.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 40 Self Check 1.What is the primary purpose of IGMP? 2.When 2 IGMP routers are located on the same Ethernet segment, which router will be the designated querier? 3.What does the ICMPv2 Query router doe when it receives a Leave Message?

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 42 Determining IGMP Version Running Determining which IGMP version is running on an interface. rtr-a>show ip igmp interface e0 Ethernet0 is up, line protocol is up Internet address is 1.1.1.1, subnet mask is 255.255.255.0 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 1.1.1.1 (this system) IGMP querying router is 1.1.1.1 (this system) Multicast groups joined: 224.0.1.40 224.2.127.254

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 43 Layer 2 Multicast Frame Switching Problem: Layer 2 flooding of multicast frames  Typical Layer 2 switches treat multicast traffic as unknown or broadcast and must flood the frame to every port (in VLAN).  Static entries may sometimes be set to specify which ports receive which groups of multicast traffic.  Dynamic configuration of these entries may reduce administration.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 44 Layer 2 Multicast Switching Solutions  Cisco Group Management Protocol (CGMP): Simple, proprietary; routers and switches  IGMP snooping: Complex, standardized, proprietary implementations; switches only

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 45 Layer 2 Multicast Frame Switching CGMP Solution 1: CGMP  Runs on switches and routers.  CGMP packets sent by routers to switches at the CGMP multicast MAC address of 0100.0cdd.dddd.  CGMP packet contains: Type field: join or leave MAC address of the IGMP client Multicast MAC address of the group  Switch uses CGMP packet information to add or remove an entry for a particular multicast MAC address.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 46 IGMP Snooping Solution 2: IGMP snooping  Switches become IGMP-aware.  IGMP packets are intercepted by the CPU or by special hardware ASICs.  Switch examines contents of IGMP messages to learn which ports want what traffic.  Effect on switch without Layer 3-aware Hardware/ASICs Must process all Layer 2 multicast packets Administration load increased with multicast traffic load  Effect on switch with Layer 3-aware Hardware/ASICs Maintain high-throughput performance but cost of switch increases

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 47 Self Check 1.What command is used to determine the version of IGMP active on an interface? 2.How does a typical layer 2 switch treat multicast traffic? 3.What is CGMP? 4.What type of switch is recommending for use with IGMP snooping?

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 48 Summary  IGMPv2 is a protocol used by multicast clients to join a multicast group.  IGMPv3 allows a receiver to specify a source.  If controls such as CGMP and IGMP snooping are not added at the Ethernet switching level, all multicast frames are flooded.  CGMP is a Cisco proprietary protocol used to implement multicast efficiently.  IGMP snooping is a standard protocol that has a function similar to CGMP.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 49 Resources  Wikipedia IGMP article http://en.wikipedia.org/wiki/IGMP  Multicast in a Campus Network: CGMP and IGMP Snooping http://www.cisco.com/warp/public/473/22.html  IP Multicast Glossary of Terms http://www.cisco.com/en/US/tech/tk828/tech_brief0900aecd801 bca26.html

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 51 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.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 53 Multicast Protocol Basics Types of multicast distribution trees:  Source distribution trees; also called shortest path trees (SPTs)  Shared distribution trees; rooted at a meeting point in the network A core router serves as a rendezvous point (RP)

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 54 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

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 55 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

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 56 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

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 57 Multicast Distribution Trees Receiver 1 B E AF Source 1Notation: (*, G) * = All Sources G = Group C Receiver 2 Source 2 (RP) PIM Rendezvous Point Shared Tree Source Tree D(RP) Shared Distribution Tree

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 58 Multicast Distribution Tree Identification (S,G) entries – Source Distribution Trees  For this particular source sending to this particular group  Traffic is forwarded through the shortest path from the source (*,G) entries – Shared Trees  For any (*) source sending to this group  Traffic is forwarded through a meeting point for this group

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 59 Multicast Distribution Trees Characteristics 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

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 60 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 of router memory and packet delivery delay.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 62 Protocols for IP Multicast Routing PIM is used between routers so that they can track which multicast packets to forward to each other and to their directly connected LANs.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 63 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 and prune the flows where there are no receivers using a periodic flood-and-prune mechanism. Sparse mode protocols use an explicit join mechanism where distribution trees are built on demand by explicit tree join messages sent by routers that have directly connected receivers.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 64 Multicast Tree Creation PIM Join/Prune Control Messages  Used to create/remove Distribution Trees Shortest Path trees  PIM control messages are sent toward the Source Shared trees  PIM control messages are sent toward RP

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 65 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.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 66 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.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 67 Reverse Path Forwarding (RPF) RPF Calculation  Based on Source Address.  Best path to source found in Unicast Route Table.  Determines where to send Joins.  Joins continue towards Source to build multicast tree.  Multicast data flows down tree. 10.1.1.1 E1 E2 Unicast Route Table Network Interface 10.1.0.0/24 E0 Join E0

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 69 Reverse Path Forwarding (RPF) RPF Calculation  What if we have equal-cost paths? We can’t use both.  Tie-Breaker Use highest Next-Hop IP address. 10.1.1.1 E1E0 E2 Unicast Route Table Network Intfc Nxt-Hop 10.1.0.0/24 E0 1.1.1.1 10.1.0.0/24 E1 1.1.2.1 1.1.2.11.1.1.1 Join

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 70 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.What is the RPF interface? 5.What if the RFP calculation finds 2 equal-cost paths?

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 75 Self Check 1.What happens to packets arriving through the non- RPF interface? 2.When would prune messages be sent on the RPF interface? 3.How often do prune messages expire in PIM-DM? 4.What happens when the prune messages expire?

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 77 PIM Sparse Mode  PIM-SM works with any of the underlying 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.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 79 PIM-SM Sender Registration Receiver RP (S, G) Join Source Shared Tree (S, G) Register (unicast) Source Tree (S, G) State created only along the Source Tree. Traffic Flow

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 80 PIM-SM Sender Registration Receiver RP Source Shared Tree Source Tree RP sends a Register-Stop back to the first-hop router to stop the Register process. (S, G) Register-Stop (unicast) Traffic Flow (S, G) Register (unicast) (S, G) traffic begins arriving at the RP through the Source tree.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 81 PIM-SM Sender Registration Receiver RP Source Shared Tree Source Tree Traffic Flow Source traffic flows natively along SPT to RP. From RP, traffic flows down the Shared Tree to Receivers.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 82 PIM-SM SPT Switchover Receiver RP (S, G) Join Source Source Tree Shared Tree Last-hop router joins the Source Tree. Additional (S, G) State is created along new part of the Source Tree. Traffic Flow

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 83 PIM-SM SPT Switchover Receiver RP Source Source Tree Shared Tree (S, G)RP-bit Prune Traffic begins flowing down the new branch of the Source Tree. Additional (S, G) State is created along along the Shared Tree to prune off (S, G) traffic. Traffic Flow

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 84 PIM-SM SPT Switchover Receiver RP Source Source Tree Shared Tree (S, G) Traffic flow is now pruned off of the Shared Tree and is flowing to the Receiver through the Source Tree. Traffic Flow

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 85 PIM-SM SPT Switchover Receiver RP Source Source Tree Shared Tree (S, G) traffic flow is no longer needed by the RP so it Prunes the flow of (S, G) traffic. Traffic Flow (S, G) Prune

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 86 PIM-SM SPT Switchover Receiver RP Source Source Tree Shared Tree (S, G) Traffic flow is now only flowing to the Receiver through a single branch of the Source Tree. Traffic Flow

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 87 “The default behavior of PIM-SM is that routers with directly connected members will join the Shortest Path Tree as soon as they detect a new multicast source.” PIM-SM Frequently Forgotten Fact

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 89 Self Check 1.What types of deployments is PIM-SM appropriate for? 2.When using PIM-SM, to what device does the receiver send a Join when wishing to receive multicast traffic? 3.How is a Register message used? 4.Explain the implications of the default value of the SPT-Threshold in Cisco routers. 5.Describe the potential issues with PIM-SM.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 90 Summary  IP multicast requires multiple protocols and processes for proper packet forwarding.  Source and shared trees may be used to define multicast packet flows to group members.  Multicast routing utilizes the distribution trees for proper packet forwarding.  PIM is the routing protocol for multicast.  PIM-DM uses flood and prune.  PIM-SM uses less device and bandwidth resources and is typically chosen to implement multicast.  PIM sparse-dense mode is the recommended methodology for maximum efficiency in IP multicast.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 92 Resources  Internet Protocol IP Multicast Technology http://www.cisco.com/en/US/tech/tk828/tech_brief09186a00800 a4415.html  IP Multicast Deployment Fundamentals http://www.cisco.com/en/US/tech/tk828/tech_brief09186a00800 e9952.html  Cisco IOS Multicast Q&A http://www.cisco.com/en/US/tech/tk828/technologies_q_and_a_ item09186a00801bb25d.shtml

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 94 Objectives  Enable PIM Sparse Mode and Sparse-Dense Mode on a router interface.  Verify the multicast routing table.  Determine if PIM neighbors are correctly configured.  Verify RP information and the IGMP group state.  Configure a router as a statically connected member.  Verify IGMP snooping.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 96 Enabling IP Multicast Routing ip multicast-routing router(config)#  Enables multicast routing.  Enabling IP multicast routing allows the Cisco IOS software to forward multicast packets.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 97 Enabling PIM on an Interface ip pim { sparse-mode | sparse-dense-mode } router(config-if)#  Enables PIM SM on an interface; the sparse-dense-mode option enables mixed sparse-dense groups.  Enabling PIM on an interface also enables IGMP operation on that interface.  Recommended method is to use sparse-dense-mode option.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 98 Announcing the RP and the Group Range It Serves ip pim send-rp-announce {interface type} scope {ttl} group-list {acl} router(config)#  Configures a router to be the RP for the local group as defined in the access list.  The following example advertises the IP address of Ethernet 0 as the RP for the administratively scoped groups: ip pim send-rp-announce ethernet0 scope 16 group-list 1 access-list 1 permit 239.0.0.0 0.255.255.255 router(config)#

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 99 Assigning the RP Mapping Agent ip pim send-rp-discovery {interface type} scope {ttl} router(config)#  The RP mapping agent is the router that tells other routers which group-to-RP range to use.  Such a role is necessary in the event of conflicts (such as overlapping group-to-RP ranges).  Find a router whose connectivity is not likely to be interrupted and assign it the role of RP-mapping agent.  All routers within ttl number of hops from the source router receive the Auto-RP Discovery messages.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 100 Self Check 1.What is the purpose if the ip multicast-routing command? 2.How is IGMP enabled on an interface? 3.What is the recommended method for configuring an interface for PIM-SM operation? 4.What is the potential issue when configuring an interface for sparse mode or dense mode, rather than sparse-dense? 5.What is the RP mapping agent?

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 102 Inspecting Multicast Routing Table  Displays the contents of the IP multicast routing table summary: Displays a one-line, abbreviated summary of each entry in the IP multicast routing table. count: Displays statistics about the group and source, including number of packets, packets per second, average packet size, and bits per second. active: Displays the rate at which active sources are sending to multicast groups. Active sources are those sending at a rate specified in the kbps argument or higher. The kbps argument defaults to 4 kbps. show ip mroute [group-address] [summary] [count] [active kbps] router#

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 103 show ip mroute NA-1#sh ip mroute IP Multicast Routing Table Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected L - Local, P - Pruned, R - RP-bit set, F - Register flag, T - SPT-bit set, J - Join SPT, M - MSDP created entry, X - Proxy Join Timer Running, A - Advertised via MSDP, U - URD, I - Received Source Specific Host Report Outgoing interface flags: H - Hardware switched Timers: Uptime/Expires Interface state: Interface, Next-Hop or VCD, State/Mode (*, 224.1.1.1), 00:07:54/00:02:59, RP 10.127.0.7, flags: S Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: Serial1/3, Forward/Sparse, 00:07:54/00:02:32 (172.16.8.1, 224.1.1.1), 00:01:29/00:02:08, flags: TA Incoming interface: Serial1/4, RPF nbr 10.139.16.130 Outgoing interface list: Serial1/3, Forward/Sparse, 00:00:57/00:02:02

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 104 Finding PIM Neighbors show ip pim interface [type number] [count] router#  Displays information about interfaces configured for PIM show ip pim neighbor [type number] router#  Lists the PIM neighbors discovered by the router mrinfo [hostname | address] router#  Queries which neighboring multicast routers are peering with the local router or router specified

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 105 show ip pim interface NA-2#show ip pim interface Address Interface Ver/ Nbr Query DR DR Mode Count Intvl Prior 10.139.16.133 Serial0/0 v2/S 1 30 1 0.0.0.0 10.127.0.170 Serial1/2 v2/S 1 30 1 0.0.0.0 10.127.0.242 Serial1/3 v2/S 1 30 1 0.0.0.0

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 106 show ip pim neighbor NA-2#show ip pim neighbor PIM Neighbor Table Neighbor Interface Uptime/Expires Ver DR Address Priority 10.139.16.134 Serial0/0 00:01:46/00:01:28 v2 None 10.127.0.169 Serial1/2 00:01:05/00:01:40 v2 1 (BD) 10.127.0.241 Serial1/3 00:01:56/00:01:18 v2 1 (BD)

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 107 Checking RP Information Displays active RPs that are cached with associated multicast routing entries. Mapping—displays all group-to-RP mappings that the router is aware of show ip pim rp [group-name | group-address | mapping] router(config)# Displays how IP multicast routing does Reverse Path Forwarding (RPF). Source Address—source address of the host for which RPF information is displayed Name—name of the host for which RPF information is displayed show ip rpf {source address | name } router(config)#

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 108 show ip pim rp P4-2#show ip pim rp Group: 224.1.2.3, RP: 10.127.0.7, uptime 00:00:20, expires never P4-2#show ip pim rp mapping PIM Group-to-RP Mappings Group(s) 224.0.1.39/32 RP 10.127.0.7 (NA-1), v1 Info source: local, via Auto-RP Uptime: 00:00:21, expires: never Group(s) 224.0.1.40/32 RP 10.127.0.7 (NA-1), v1 Info source: local, via Auto-RP Uptime: 00:00:21, expires: never Group(s): 224.0.0.0/4, Static RP: 10.127.0.7 (NA-1)

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 109 show ip rpf (towards the RP) NA-2#show ip rpf 10.127.0.7 RPF information for NA-1 (10.127.0.7) RPF interface: Serial1/3 RPF neighbor: ? (10.127.0.241) RPF route/mask: 10.127.0.7/32 RPF type: unicast (ospf 1) RPF recursion count: 0 Doing distance-preferred lookups across tables (towards the source) NA-2#show ip rpf 10.139.17.126 RPF information for ? (10.139.17.126) RPF interface: Serial0/0 RPF neighbor: ? (10.139.16.134) RPF route/mask: 10.139.17.0/25 RPF type: unicast (ospf 1) RPF recursion count: 0 Doing distance-preferred lookups across tables

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 110 Checking the Group State show ip igmp interface [type number] router#  Displays multicast-related information about an interface show ip igmp groups [group-address | type number] router#  Displays the multicast groups that are directly connected to the router and that were learned via IGMP

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 111 Configure a Router as a Group Member ip igmp join-group group address Router (config-if)#  Configure a router to join a specific multicast group and enable IGMP on an interface. ip igmp static-group group-address Router (config-if)#  Configures the router as a statically connected member of a group

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 112 show ip igmp interface rtr-a>show ip igmp interface e0 Ethernet0 is up, line protocol is up Internet address is 1.1.1.1, subnet mask is 255.255.255.0 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 1.1.1.1 (this system) IGMP querying router is 1.1.1.1 (this system) Multicast groups joined: 224.0.1.40 224.2.127.254

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 113 show ip igmp groups rtr-a>sh ip igmp groups IGMP Connected Group Membership Group Address Interface Uptime Expires Last Reporter 224.1.1.1 Ethernet0 6d17h 00:01:47 1.1.1.12 224.0.1.40 Ethernet0 6d17h never 1.1.1.17

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 114 Verifying IGMP Snooping on a Switch Displays information about multicast groups. If igmp keyword is used, only IGMP-learned information is shown. show multicast group [igmp] [mac_addr] [vlan_id] switch> Displays information on dynamically learned and manually configured multicast router ports. If igmp keyword is used, only IGMP-learned information is shown. show multicast router [igmp] [mod_num/port_num] [vlan_id] switch>

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 116 Switch> show igmp statistics 10 IGMP enabled IGMP statistics for vlan 10: Transmit: General Queries: 0 Group Specific Queries: 0 Reports: 0 Leaves: 0 Receive: General Queries: 1 Group Specific Queries: 0 Reports: 2 Leaves: 0 Total Valid pkts: 4 Total Invalid pkts: 0 Other pkts: 1 MAC-Based General Queries: 0 Failures to add GDA to EARL: 0 Topology Notifications: 0 Verifying IGMP Snooping—Example (Cont.)

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 117 Switch> show multicast router igmp Port Vlan ---------- ---------------- 4/1 10 Total Number of Entries = 1 '*' - Configured '+' - RGMP-capable Switch> show multicast group igmp VLAN Dest MAC/Route Des [CoS] Destination Ports or VCs / [Protocol Type] ---- --------------------------------------------------------------------- 10 01-00-5e-00-01-28 4/1 10 01-00-5e-01-02-03 4/1-2 Total Number of Entries = 2 Verifying IGMP Snooping—Example (Cont.)

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 118 Self Check 1.What command can be used to view the multicast routing table? 2.What commands can be used with PIM-SM to check PIM-enabled interfaces? 3.Why should the show ip pim rp mapping command be used instead of the show ip pim rp command? 4.Why might you configure a router to be a multicast group member?

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 119 Summary  Configuring a simple multicast network requires a global multicast command, a multicast command for each interface, and the specification of an RP discovery method.  Effective methods for verifying a multicast network include checking the multicast routing table and checking PIM neighbors.  Configuring IGMP snooping on an Ethernet switch avoids the problem of multicast frame flooding.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 121 Resources  Cisco IOS IP Multicast Configuration Guide http://cisco.com/en/US/partner/products/ps6350/products_confi guration_guide_book09186a0080435b9f.html  IP Multicast Deployment Fundamentals http://cisco.com/en/US/partner/tech/tk828/tech_brief09186a008 00e9952.html  Multicast Quick-Start Configuration Guide http://cisco.com/en/US/partner/tech/tk828/technologies_tech_no te09186a0080094821.shtml  Basic Multicast Troubleshooting Tools http://cisco.com/en/US/partner/tech/tk828/technologies_tech_no te09186a0080093f21.shtml

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 1 IP Multicasting: Explaining Multicast.

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© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 1 IP Multicasting: Explaining Multicast.

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Presentation on theme: "© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public BSCI Module 7 Lesson 1 1 IP Multicasting: Explaining Multicast."— Presentation transcript:

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