IP Multicasting:IP Multicasting: Explaining Multicastlsteffenel/cours/FC/BSCI7.pdf · Some of these...

IP Multicasting:IP Multicasting: Explaining Multicast

1© 2008 Cisco Systems, Inc. All rights reserved. Cisco Academy

Multicast Overview

© 2008 Cisco Systems, Inc. All rights reserved. Cisco Academy 2

IP MulticastIP MulticastDistribute information to large audiences over an IP networknetwork


Multicast AdoptionPast, Present, and FuturePast, Present, and Future

Multicast (1986Multicast (1986--2005)2005)Corporate MXU & Content

Surveillance Law Enforcement

and Federal

E Learning150 Universities in

Corporate CommunicationHP, IBM, Intel, Ford,

BMW, Dupont

MXU & Content ProvidersFastweb, B2,

Yahoo, BBC, CNN

IPv6 MulticastNTT, Sony, Panasonic,

Multicast VPNC&W, MCI, AT&T,

Financials NASDAQ, NYSE,

LIFE, Morgan, GS, Prudential

US, Hawaii, Oregon, USC, UCLA, Berkley

C&W, MCI, AT&T, TI, FT, DT, NTT

Early AdoptersNASA, DOD,

Cisco, Microsoft, Sprint

Prudential

ResearchResearch Community

MBONE


1992 1996 1997 1998 2000 2001 2002 2003 2004 20051986Time

Why Multicast?Why Multicast?

Used when sending same data to multiple receiversUsed e se d g sa e da a o u p e ece e s

Better bandwidth utilization

Less host/router processingLess host/router processing

Used when addresses of receivers unknown

Used hen sim ltaneo s deli er for a gro p ofUsed when simultaneous delivery for a group of receivers is required (simulcast)


IP Transmission Schemes


Multicast Advantages

Enhanced efficiency: Controls network traffic and reduces server and CPU loadsreduces server and CPU loadsOptimized performance: Eliminates traffic redundancyDistributed applications: Makes multipoint applicationsDistributed applications: Makes multipoint applications possible


Other Multicast AdvantagesOther Multicast Advantages

For the equivalent amount of multicast traffic, the sender needs much less processing power and bandwidth.

Multicast packets do not impose as high a rate of b d idth tili ti i t k t thbandwidth utilization as unicast packets, so there is a greater possibility that they will arrive almost simultaneously at the receivers.


Multicast Disadvantages

Multicast is UDP-based.

Best-effort deliveryBest effort deliveryHeavy drops in Voice trafficModerate to Heavy drops in Video

No congestion avoidance

Duplicate packets may be generated

Out-of-sequence delivery may occur

Efficiency issues in filtering and in security


c e cy ssues te g a d secu ty

Types of Multicast ApplicationsOne-to-many

A single host sending to two or more (n) receivers• Audio or video distribution• Push media• Announcements• Monitoring

Many-to-manyAny number of hosts sending to the same multicast group; hosts are also members of the group (sender = receiver)

• Collaboration• Concurrent processing• Distributed interactive simulations

M tMany-to-oneAny number of receivers sending data back to a source (via unicast or multicast)

• Resource discovery


• Data collection• Auctions• Polling

IP Multicast ApplicationsCorporate BroadcastsLive TV and Radio Broadcast

t th D kt

IP Multicast Applications

to the Desktop

Training


Real-Time Data Delivery—Financial

Multicast Addressing


IP Multicast Address StructureIP Multicast Address Structure

IP group addresses:IP group addresses:Class D address (high-order three bits are set)

Range from 224.0.0.0 through 239.255.255.255


Multicast Addressing gIPv4 Header

Version IHL Type of Service Total Length

Identification Flags Fragment Offset

Version IHL Type of Service Total Length

Time to Live Protocol Header Checksum

Source Address

Destination

Source

Destination

1.0.0.0 - 223.255.255.255 (Class A, B, C)Source

Options Padding

Destination AddressDestination224.0.0.0 - 239.255.255.255 (Class D) Multicast Group Address Range

Destination


IP Multicast Address Groups

Local scope addresses, reserved by IANA for network lprotocol use.

224.0.0.0 to 224.0.0.255

Global scope addresses are allocated d namicallGlobal scope addresses are allocated dynamicallythroughout the Internet.

224.0.1.0 to 238.255.255.255

Administratively scoped addresses are reserved for use inside of private domains.

239.0.0.0 to 239.255.255.255


Local Scope AddressesLocal Scope AddressesWell-known addresses assigned by IANA

Reserved use: 224.0.0.0 through 224.0.0.255

224.0.0.1 (all multicast systems on subnet)224.0.0.2 (all routers on subnet)224 0 0 4 (all Distance Vector Multicast Routing Protocol (DVMRP)224.0.0.4 (all Distance Vector Multicast Routing Protocol (DVMRP) 224.0.0.5 (all OSPF Routers on a subnet)224.0.0.6 (all OSPF DRs on a subnet)224.0.0.9 (all RIPv2 routers on a subnet)224.0.0.10 (all EIGRP routers on a subnet)224 0 0 13 (all PIM 2 ro ters)


224.0.0.13 (all PIMv2 routers)

Global Scope Addresses

Transient addresses, assigned and reclaimed dynamically (within applications):

Global scope range: 224.0.1.0-238.255.255.255224.2.X.X usually used in MBONE applications

Some of these addresses have been registered with IANA, for example IP address 224.0.1.1 has been reserved for Network Time Protocol (NTP).

A li ti th t lti t dd i th 224 0 1 2/32 224 0 1 22/23 dApplications that use multicast addresses in the 224.0.1.2/32, 224.0.1.22/23, and 224.0.2.2/32 ranges have been demonstrated to be vulnerable to exploitation, which has led to serious security problems.

Addresses in the 232 0 0 0 to 232 255 255 255 range are reserved for SourceAddresses in the 232.0.0.0 to 232.255.255.255 range are reserved for Source Specific Multicast (SSM). SSM is an extension of Protocol Independent Multicast (PIM), which allows for an efficient data delivery mechanism in one-to-many communications.


Administratively Scoped AddressesAdministratively Scoped Addresses

Transient addresses assigned and reclaimedTransient addresses, assigned and reclaimed dynamically (within applications):

Limited (local) scope: 239 0 0 0/8 for private IPLimited (local) scope: 239.0.0.0/8 for private IP multicast addresses (RFC-2365)

Site-local scope: 239.255.0.0/16Organization-local scope: 239.192.0.0 to 239.251.255.255


Layer 2 Multicast AddressingLayer 2 Multicast Addressing

IEEE 802 3 MAC Address FormatIEEE 802.3 MAC Address Format


IANA Ethernet MAC Address RangeIANA Ethernet MAC Address RangeIANA owns a block of Ethernet MAC addresses that start with 01 00 5E i h d i l f t H lf f thi bl k i ll t d01.00.5E in hexadecimal format. Half of this block is allocated for multicast addresses.

Th f 0100 5 00 0000 th h 0100 5 7f ffff i thThe range from 0100.5e00.0000 through 0100.5e7f.ffff is the available range of Ethernet MAC addresses for IP multicast.

01-00-5e-00-00-00

through

01 00 5 7f ff ff


01-00-5e-7f-ff-ff

IANA Ethernet MAC Address RangeIANA Ethernet MAC Address RangeAvailable range of MAC addresses for IP multicast

00000001:00000000:01011110:00000000:00000000:00000000

through

00000001:00000000:01011110:01111111:11111111:11111111

Within this range, these MAC addresses have the first 25 bits in commonbits in common. The remaining 23 bits are available for mapping to the lower 23 bits of the IP multicast group address


lower 23 bits of the IP multicast group address.

Multicast Addresses Mapping Layer 3 to Layer 2Layer 2

Layer 3

La er 2Layer 2


Multicast AddressingMulticast AddressingIP Multicast MAC Address Mapping

(FDDI & Ethernet)

Be Aware of the 32:1 Address OverlapBe Aware of the 32:1 Address Overlap

(FDDI & Ethernet)

224.1.1.1224.129.1.1

32 - IP Multicast Addresses

225.1.1.1225.129.1.1

.

. 0x0100 5E01 0101

1 - Multicast MAC Address(FDDI and Ethernet)

.238.1.1.1238.129.1.1239 1 1 1

0x0100.5E01.0101


239.1.1.1239.129.1.1

Madcap in MS ServerMulticast Address Dynamic Client Allocation Protocol (MADCAP) allows a client workstation to“lease” a multicast address from a MADCAP server in a manner similar to how it “leases” anIP address from a DHCP server.

When a MADCAP client workstation wants to “lease” a multicast address, first it must locate


the nearest MADCAP Servers. This is accomplished by multicasting a MADCAP DISCOVERmessage to the MADCAP Scope Relative multicast address (-1) in the Site-Local scope, (forinstance, 239.255.255.254). (Note: This is why it is important to adhere to the conventions forthe Site-Local scope defined in RFC 2365.)

How are Multicast Addresses Assigned? Static Global Group Address Assignment

Temporary method to meet immediate needs

Group range: 233.0.0.0 – 233.255.255.255Your AS number is inserted in middle two octetsRemaining low-order octet used for group assignmentFor example, AS 62010 is written in hexadecimal format as "F23A."

•This value is separated into two parts F2 and 3A and thoseThis value is separated into two parts, F2 and 3A and those numbers, converted to decimal would be 242 and 58.

•This would yield a multicast GLOP address of 233.242.58.0/24.

Defined in RFC 2770“GLOP Addressing in 233/8”

M l dd ll ti b th d i i till th t


Manual address allocation by the admin is still the most common practice.

Learning About Multicast Sessions

Potential receivers have to learn about multicast t i il bl b f lti tstreams or sessions available before a multicast

application is launched.

Possibilities:Possibilities:

Another multicast application sending to a well-known group whose members are all potential receiversg p p

Directory services

Web page e-mailWeb page, e-mail

Session Announcement Protocol (SAP)


sdr—Session DirectoryThe Session Directory (sd) application acts as a guide, displaying multicast y ( ) pp g , p y gcontent. A client application runs on a PC and lets the user know what content is available. This directory application uses either Session Description Protocol (SDP) or Session Announcement Protocol (SAP) to learn about the content.

The original sd application served as a means to announce available sessions and to assist in creating new sessions. The initial sd tool was revised, resulting in the Session Description Protocol tool (referred to in this course as “SDR”), which is an applications tool that allows the following:

•Session description and its announcement•Transport of session announcement via well-known multicast groups (224.2.127.254) •Creation of new sessions


A Cisco IP/TV ExampleTh SDR h i h i thi Ci IP/TV lThe SDR mechanisms are shown in this Cisco IP/TV example.

Cisco IP/TV generally has three components:• Server (the source)• Content Manager (the “directory server”)• Viewer (the receiver)

The Viewers can either:• Contact the Content Manager directly (by unicast) and request the list of available

programs (sessions, streams) from it• Listen to periodic SAP announcements


Cisco IP/TV uses SAP to transport the SDR sessions to the viewer. The standard SDR format for session description is used.

Multicasting Topics/Protocols


IGMP Overview

IGMP – Joining/Leaving Multicast GroupsGroups


Controlling Multicasts IGMPIGMPIGMP – Internet Group Management Protocol

–Used primarily by multicast hosts to signal their local multicast routerthey wish to join a specific multicast groupthey wish to join a specific multicast group

IGMP

ReceiverJoin/Leave

IGMPIGMP

Receiver


IGMPMulticasting on a single physical segment is simple.

MulticastTraffic

Sender Receiver

MulticastTraffic

The sender (server) specifies a destination multicastThe sender (server) specifies a destination multicastaddress and the receiving devices (clients) indicate thatthey want to receive these packets for a given multicastdd ( d t)


address (and port).–The application at both ends handles this.

IGMPComplications arise when multicasting is extended beyonda single physical network and multicast packets passthrough routers.g

MulticastTraffic

MulticastTraffic

Sender ReceiverJoin/LeaveIGMP

Sending and receiving multicast traffic requires coordinationSending and receiving multicast traffic requires coordinationfrom all devices participating in the multicast.

Before multicast traffic can traverse the network, routers


,need to know which hosts (if any) on a specific physicalnetwork belong to a given multicast group.

Internet Group Management Protocol (IGMP)How hosts tell routers about group membership

Routers solicit group membership from directly connected hostsRFC 1112 specifies IGMPv1Supported by Win95 Unix etcSupported by Win95, Unix, etc.No way to expressly leave a multicast group. It’s up to the router to timeout the group membership

RFC 2236 specifies IGMPv2Supported by Win98, 2k, latest Win95/UNIX updatespp y pIncludes “leave processing” mechanism


Internet Group Management Protocol (IGMP)H h ll b b hiHow hosts tell routers about group membership

IGMP v3lite Host SignallingIGMP v3lite is a Cisco-developed transitional solution for application developers to p pp pimmediately start programming SSM applications. It allows you to write and run SSM applications on hosts that do not yet support IGMPv3 in their operating system kernel. Applications must be compiled with the Host Side IGMP Library (HSIL) for IGMP v3lite. This software provides applications with a subset of the IGMPv3 applications programming interface (API) that is required to write SSM applications. HSIL was developed for Cisco by Talarian and is available from the following web page: p y g p g

http://www.talarianmulticast.com/cgi-bin/igmpdownld

RFC 3376 specifies IGMPv3RFC 3376 specifies IGMPv3Supports "source filtering," which enables a multicast receiver host to signal toa router which groups it wants to receive multicast traffic from, and from whichsource(s) this traffic is expected.


( ) pIn addition, IGMPv3 supports the link local address 224.0.0.22, which is thedestination IP address for IGMPv3 membership reports; all IGMPv3-capablemulticast routers must listen to this address.

IGMPv1 - RFC 1112With IGMPv1, routers send periodic membership queries to the multicast address 224.0.0.1. Hosts send membership reports to the group multicast address they want to join; hosts silently leave the multicast group.

In IGMPv1, there is no election of an IGMP querier. If more than one router on the segment exists, all the routers send periodic IGMP queries.

If there are multiple routers on a LAN, a designated router (DR) must be elected to avoid duplicating multicast traffic for connected hosts. PIM routers follow anto avoid duplicating multicast traffic for connected hosts. PIM routers follow an election process to select a DR. The PIM router with the highest IP address becomes the DR. The DR is responsible for the following tasks:

•Sending PIM register and PIM Join and Prune messages toward the rendezvous point (RP) to inform it about host group membership.

•Sending IGMP host-query messages


Sending IGMP host query messages.

•Sending host-query messages by default every 60 seconds in order to keep the IGMP overhead on hosts and networks very low.

IGMPv2RFC 2236

Group-specific queryRouter sends query membership message to a single group rather than all q y p g g g phosts (reduces traffic).

Leave group messageHost sends leave message if it leaves the group and is the last member (reduces leave latency in comparison to v1).

Query-interval response timeThe Query router sets the maximum Query-Response time (controls b rstiness and fine t nes lea e latencies)burstiness and fine-tunes leave latencies).

Querier election processIGMPv2 routers can elect the Query Router without relying on the multicast routing protocolrouting protocol.


IGMPv2 Joining a GroupIGMPv2—Joining a Group

224.1.1.1

Join Group


IGMPv2 Leaving a GroupIGMPv2—Leaving a Group

IGMPv2 has explicit Leave Group messages, which reduces overall leave latency


reduces overall leave latency.

IGMPv2 Leaving a Group (Cont )IGMPv2—Leaving a Group (Cont.)

Hosts H2 and H3 are members of group 224.1.1.1.

1 H2 d l


1. H2 sends a leave message.


2. Router sends group-specific query.


KA1

KA1 In the original slide the screen of computer H3 was a different color to bring it to the attention of the learner. Please change the screen color of computer H3 from the light teal color to a white.Karen Alderson, 10/19/2006


3. A remaining member host sends report, so group remains active


remains active.

Unlike IGMPv1, in which the DR and the IGMP querier are typically thesame router, in IGMPv2 the two functions are decoupled. The DR andthe IGMP querier are selected based on different criteria and may bethe IGMP querier are selected based on different criteria and may bedifferent routers on the same subnet. The DR is the router with thehighest IP address on the subnet, whereas the IGMP querier is the routerwith the lowest IP address.

Query messages are used to elect the IGMP querier as follows:1. When IGMPv2 routers start, they each multicast a general querymessage to the all systems group address of 224 0 0 1 with their interfacemessage to the all-systems group address of 224.0.0.1 with their interfaceaddress in the source IP address field of the message.

2. When an IGMPv2 router receives a general query message, the routercompares the source IP address in the message with its own interfaceaddress. The router with the lowest IP address on the subnet is electedthe IGMP querier.

3. All routers (excluding the querier) start the query timer, which isreset whenever a general query message is received from the IGMPquerier. If the query timer expires, it is assumed that the IGMP querier has

d d th l ti i f d i t l t


gone down, and the election process is performed again to elect a newIGMP querier.By default, the timer is two times the query interval.

Routers Running IGMPv3

IGMPv3 adds support in Cisco IOS software for source filtering, whichenables a multicast receiver host to signal to a router which groups it wantsto receive multicast traffic from and from which sources this traffic isto receive multicast traffic from, and from which sources this traffic isexpected.

IGMPv3 supports applications that explicitly signal sources from which theywant to receive traffic. With IGMPv3, receivers signal membership to amulticast group in the following two modes:

•INCLUDE mode - In this mode the receiver announces membership to aINCLUDE mode In this mode, the receiver announces membership to agroup and provides a list of IP addresses (the INCLUDE list) from which itwants to receive traffic.

EXCLUDE d I thi d th i b hi t•EXCLUDE mode - In this mode, the receiver announces membership to agroup and provides a list of IP addresses (the EXCLUDE list) from which itdoes not want to receive traffic.


IGMPv3 Joining a GroupIGMPv3—Joining a Group

Joining member sends IGMPv3 report to 224.0.0.22 immediately upon joining.


IGMPv3 Joining Specific Source(s)IGMPv3—Joining Specific Source(s)

IGMPv3 Report contains desired sources in the Include list Only “Included” sources are joined


Include list. Only Included sources are joined.

IGMPv3 Maintaining StateIGMPv3—Maintaining State

Router sends periodic queries:All IGMPv3 members respond.


Reports contain multiple group state records.

Multicast Listener Discovery Protocol

RFC 2710 defines specifications for the Multicast Listener Discovery(MLD) protocol. MLD is derived from IGMPv2 and is designed for IPv6.The operation of MLD is similar to IGMPv2. The major differencesbetween IGMPv2 and MLD are as follows:

All the multicast devices on a subnet use a special IPv6 link-local addresspas their source address in their communication to other multicastdevices. The use of the link-local source address prevents the MLD packetfrom traveling beyond the local link.

In MLD, when a host wants to leave a group, it sends a Done message.The Done message is similar to the IGMPv2 Leave message. It isaddressed to the all-routers IPv6 link-local scope address, FF02::2.In MLD, the router Queries are called Multicast Listener Queries. TheGeneral Queries are addressed to the all-nodes IPv6 link-local scopeaddress, FF02::1. When a router receives a Done message, it sends a


Multicast-Address-Specific Query. Its function is similar to IGMPv2Group-Specific Query.

Determining IGMP Version RunningDetermining which IGMP version is running on an interface.

t h i i i t f 0rtr-a>show ip igmp interface e0Ethernet0 is up, line protocol is up

Internet address is 1.1.1.1, subnet mask is 255.255.255.0IGMP is enabled on interfaceCurrent IGMP version is 2CGMP is disabled on interfaceCGMP is disabled on interfaceIGMP query interval is 60 secondsIGMP querier timeout is 120 secondsIGMP max query response time is 10 secondsInbound IGMP access group is not setMulticast routing is enabled on interface


Multicast TTL threshold is 0Multicast 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

IGMP Layer 2 Issues

Non-Receiver

CGMP

Multicast

CGMP

Receiver

CGMP

MulticastTraffic


Layer 2 Multicast Frame SwitchingLayer 2 Multicast Frame SwitchingProblem: Layer 2 flooding of multicastfframes

Typical Layer 2 switches treat multicast traffic as unknown ormulticast 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 trafficgroups of multicast traffic.

Dynamic configuration of these entries may reduce administration.


y

Layer 2 Multicast Switching SolutionsLayer 2 Multicast Switching Solutions

1. Cisco Group Management Protocol (CGMP):1. Cisco Group Management Protocol (CGMP):Simple, proprietary; routers and switches

2. IGMP snooping: With IGMP snooping, the switch intercepts IGMP messages from the host and updates the MAC table accordingly. To implement IGMP snooping without suffering switch performance loss, it p g g p ,is necessary to make the switch Layer 3-aware. This result is typically accomplished by using Layer 3 ASICs.ASICs.


Layer 2 Multicast Frame Switching CGMPCGMPSolution 1: CGMP

R it h d tRuns on switches and routers.

CGMP packets sent by routers to switches at the CGMP multicast MACswitches at the CGMP multicast MAC address of 0100.0cdd.dddd.CGMP packet contains:p

Type field: join or leave MAC address of the IGMP clientMulticast MAC address of the group

Switch uses CGMP packet information to add or remove an entry for a particular


add or remove an entry for a particular multicast MAC address.

CGMP

CGMP Non-Receiver

CGMP

MulticastTraffic

CGMPIGMP

When the router sees an IGMP packet the router creates a CGMP packetReceiver

CGMPTraffic

When the router sees an IGMP packet, the router creates a CGMP packet.This CGMP packet contains the request type, either a join or a leave, themulticast group address, and the actual MAC address of the client (from theSource MAC address in the Ethernet frame).

The packet is sent to a well-known address (0x0100.0cdd.dddd) to which allswitches listen.

–Each switch then interprets the packet and creates the proper entries in aforwarding table.

The important information in the CGMP messages is one or more pairs of MACaddresses:


Group Destination Address (GDA)

Unicast Source Address (USA)

CGMP J iCGMP Join

The IGMP membership report is received by the Layer 2 switch and forwarded to the CGMP server for normal IGMP processing.

The CGMP server, receives the membership report and translates the report intoThe CGMP server, receives the membership report and translates the report into a CGMP join message. It sends the CGMP join message to the switch through the well-known CGMP multicast MAC address (0x0100.0cdd.dddd). When the Layer 2 switch receives the join message, it updates its forwarding table to include the MAC-equivalent of the group destination address and the applicable


include the MAC equivalent of the group destination address and the applicable input and output switch ports.

IGMP Snooping

Solution 2: IGMP snoopingSwitches become IGMP awareSwitches 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-awareEffect on switch without Layer 3 aware Hardware/ASICs

Must process all Layer 2 multicast packetsAd i i t ti l d i d ith lti t t ffiAdministration load increased with multicast traffic load

Effect on switch with Layer 3-aware Hardware/ASICs


Maintain high-throughput performance but cost of switch increases

IGMP Snooping

H1 sends an IGMP Join message for 226 6 6 6 At Layer 2H1 sends an IGMP Join message for 226.6.6.6. At Layer 2,H1 uses the multicast MAC address 0x0100.5e06.0606 (theMAC for group 226.6.6.6) as the destination address anduses its own BIA as the source address SW1 receives the


uses its own BIA as the source address. SW1 receives thepacket on its fa0/1 port and, noticing that it is an IGMPpacket, forwards the packet to the switch CPU.

IGMP Snooping

H2 sends an IGMP Join message for 226.6.6.6. At Layer 2,H2 uses the multicast MAC address 0x0100 5e06 0606 asH2 uses the multicast MAC address 0x0100.5e06.0606 asthe destination address and uses its own BIA as thesource address. SW1 receives the packet on its fa0/2 port,and its switching engine examines the packet The process


and its switching engine examines the packet. The processof analyzing the packet, as described in Step 1, is repeatedand the CAM table entries are updated as shown.

IGMP Snooping

Router R1 forwards the group traffic. R1 is receivingmulticast traffic for group 226.6.6.6 and starts forwardingthe traffic to SW1. SW1 starts receiving the multicast trafficon its port fa0/8.The switching engine would examine the packet and


determine that this is a non-IGMP packet, search its CAMtable, and determine that it should forward the packet onports fa0/1 and fa0/2.

IGMPv3 and IGMP Snooping

Impact of IGMPv3 on IGMP Snooping

IGMPv3 and IGMP Snooping

p p gIGMPv3 Reports are sent to a separate group (224.0.0.22) reduces load on switch CPUNo Report Suppression in IGMPv3No Report Suppression in IGMPv3

IGMP Snooping should not cause a serious f bl IGMP 3 i i l t dperformance problem once IGMPv3 is implemented.


MulticastMulticast Distribution TreesTrees

PIM - Protocol Independend Multicast

MulticastRouting

Protocols


Multicast Protocol BasicsMulticast Protocol BasicsTypes 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)A core router serves as a rendezvous point (RP)


Multicast Distribution TreesShortest Path or Source Distribution Tree

Multicast Distribution Trees

Source 1Notation: (S, G)

S = SourceG = Group

BA D F

G GroupSource 2

B

E

A D F

C EC


Receiver 1 Receiver 2

Multicast Distribution TreesMulticast Distribution TreesShortest Path or Source Distribution Tree

Source 1Notation: (S, G)

S = SourceG = Group

BA D F

G GroupSource 2

B

E

A D F

C EC



Multicast Distribution TreesMulticast Distribution TreesShared Distribution Tree

Notation: (*, G)* = All SourcesG = Group

BA D F(RP)

E

D

C (RP) PIM Rendezvous Point

(RP)

ECShared Tree



Multicast Distribution TreesMulticast Distribution TreesShared Distribution Tree

Source 1 Notation: (*, G)* = All SourcesG = Group

BA F

Source 2

D (RP)

EC (RP) PIM Rendezvous Point

D (RP)

ECShared TreeSource Tree



Multicast Distribution Tree IdentificationMulticast 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(*,G) entriesFor any (*) source sending to this group

T ffi i f d d h h i i f hiTraffic is forwarded through a meeting point for this group


Multicast Distribution TreesMulticast Distribution Trees

CharacteristicsCharacteristics of Distribution TreesSource or Shortest Path trees

Uses more memory but optimal paths from source toUses more memory but optimal paths from source to all receivers; minimizes delay

Shared treesUses less memory but sub-optimal paths from source to all receivers; may introduce extra delay


Multicast Routing


Protocols for IP Multicast Routing

PIM is used between routers so that they can track which l i k f d h h d h i


multicast packets to forward to each other and to their directly connected LANs.

Protocol Independent Multicast (PIM)Protocol-Independent Multicast (PIM)PIM maintains the current IP multicast service mode of receiver initiated membershipreceiver-initiated membership. PIM is not dependent on a specific unicast routing protocol.pWith 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


messages sent by routers that have directly connected receivers.

Multicast Tree CreationMulticast Tree CreationPIM Join/Prune Control Messages

Used to create/remove Distribution Trees

Shortest Path treesPIM control messages are sent toward the SourcePIM control messages are sent toward the Source

Shared treesShared treesPIM control messages are sent toward RP


Multicast ForwardingMulticast Forwarding

Multicast routing operation is the opposite of unicastMulticast routing operation is the opposite of unicast routing.

Unicast routing is concerned with where the packetUnicast routing is concerned with where the packet is going.

Multicast routing is concerned with where the packet gcomes from.Multicast routing uses Reverse Path Forwarding (RPF) to

t f di lprevent forwarding loops.


Reverse Path Forwarding (RPF)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 RPFThis interface becomes the Incoming or RPF interface.

A router forwards a multicast datagram only if received on the RPF interface.


Reverse Path Forwarding (RPF)Reverse Path Forwarding (RPF)

RPF Calculation 10.1.1.1RPF Calculation

Based on Source Address.

Best path to source found in

10.1.1.1

Best path to source found in Unicast Route Table.

Determines where to send Joins.

Join

Joins continue towards Source to build multicast tree.

Join

Multicast data flows down tree.E1

E2

Unicast Route TableNetwork Interface

E0


Network Interface10.1.0.0/24 E0


10.1.1.1RPF Calculation (cont ) 10.1.1.1

J i

RPF Calculation (cont.)

Repeat for other receivers…

Join

Join

Join

E1E0

E2



RPF Calculation 10.1.1.1RPF Calculation

What if we have equal-cost paths?We can’t use bothWe can t use both.

Tie-BreakerUse highest Next-Hop IP addressUse highest Next Hop IP address.

1.1.2.11.1.1.1Join

E1E0

E2Unicast Route Table

Network Intfc Nxt-Hop10 1 0 0/24 E0 1 1 1 1


10.1.0.0/24 E0 1.1.1.110.1.0.0/24 E1 1.1.2.1

Multicast Distribution Tree CreationMulticast Distribution Tree Creation

PIM b th t d RP t d h d t tPIM uses both source trees and RP-rooted shared trees toforward datagrams; the RPF check is performed differentlyfor each, as follows:

• If a PIM router has source-tree state (that is, an (S,G) entryis present in the multicast routing table), the router performsth RPF h k i t th IP dd f th f ththe RPF check against the IP address of the source of themulticast packet.

If PIM t h h d t t t ( d li it• If a PIM router has shared-tree state (and no explicitsource-tree state), it performs the RPF check on the RP'saddress (which is known when members join the group).


PIM DensePIM Dense Mode OperationOperation


PIM DM Flood and PrunePIM-DM Flood and PruneInitial Flooding


PIM DM Flood and Prune (Cont )PIM-DM Flood and Prune (Cont.)


PIM DM Flood and Prune (Cont )PIM-DM Flood and Prune (Cont.)Results After Pruning


PIM SparsePIM Sparse Mode OperationOperation


PIM Sparse ModePIM Sparse ModePIM-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.R i j i d t th h d t ( t d t th RP) bReceivers are joined to the shared tree (rooted at the RP) by their local DR.


PIM SM Shared Tree JoinPIM-SM Shared Tree Join

RP

(*, G) Join(*, G) State created onlyalong the Shared Tree.

Receiver

Shared Tree


PIM SM Sender RegistrationPIM-SM Sender Registration

RPSource

(S, G) State created onlyalong the Source Tree.Traffic Flow

Receiver

Shared Tree

(S, G) Register (unicast)

Source Tree


(S, G) Join


RPSource

Traffic Flow

(S, G) traffic begins arriving at the RP through the Source tree

Receiver

Shared TreeSource Tree RP sends a Register-Stop

back to the first-hop router to stop the Register process.

(S, G) Register (unicast)

tree.


p g p(S, G) Register-Stop (unicast)


RPSource

Traffic FlowSource traffic flows nativelyalong SPT to RP.

Receiver

Shared TreeSource Tree

From RP, traffic flows downthe Shared Tree to Receivers.


PIM SM SPT SwitchoverPIM-SM SPT Switchover

RPSource

Last-hop router joins the Source Tree.Traffic Flow

Receiver(S, G) JoinSource TreeShared Tree Additional (S, G) State is created

along new part of the Source Tree.



RPSource

Traffic begins flowing down theTraffic Flow

ReceiverSource TreeShared Tree

(S, G)RP-bit Prune

Traffic begins flowing down the new branch of the Source Tree.Additional (S, G) State is created along the Shared Tree to


prune off (S, G) traffic.


RPSource

(S, G) Traffic flow is now pruned off of the Shared Tree Traffic Flow

ReceiverSource TreeShared Tree and is flowing to the Receiver

through the Source Tree.



RPSource

(S, G) traffic flow is no longer needed by the RP so it Prunes Traffic Flow

ReceiverSource TreeShared Tree the flow of (S, G) traffic.

(S, G) Prune



RPSource

(S, G) Traffic flow is now only flowing to the Receiver Traffic Flow

ReceiverSource TreeShared Tree through a single branch of

the Source Tree.


PIM SM EvaluationPIM-SM EvaluationEffective for Sparse or Dense distribution of multicast receivers

Advantages:

Traffic only sent down “joined” branches

Can switch to optimal source-trees for high traffic d i llsources dynamically

Unicast routing protocol-independentBasis for inter-domain multicast routing


Multiple RPs with Auto RPMultiple RPs with Auto RPPIM Sparse-Dense-Mode


MulticastMulticast BasicConfigurationg


Enabling IP Multicast RoutingEnabling IP Multicast Routing

router(config)#

ip multicast-routing

E bl lti t tiEnables multicast routing. Enabling IP multicast routing allows the Cisco IOS software to forward multicast packets.software to forward multicast packets.


Enabling PIM on an InterfaceEnabling PIM on an Interface

router(config-if)#

ip pim { sparse-mode | sparse-dense-mode }

Enables PIM SM on an interface; the sparse dense modeEnables PIM SM on an interface; the sparse-dense-mode option enables mixed sparse-dense groups.Enabling PIM on an interface also enables IGMP goperation on that interface.Recommended method is to use sparse-dense-modeoptionoption.


Announcing the RP and the Group Range It SServes

ip pim send-rp-announce {interface type} scope {ttl} group-list {acl}

router(config)#

ip pim send-rp-announce {interface type} scope {ttl} group-list {acl}

Configures a router to be the RP for the local group as defined in the access listdefined in the access list.

The following example advertises the IP address of Eth t 0 th RP f th d i i t ti l dEthernet 0 as the RP for the administratively scoped groups:

router(config)#ip pim send-rp-announce ethernet0 scope 16 group-list 1access-list 1 permit 239.0.0.0 0.255.255.255

router(config)#

Thi t d A t RP t 224 0 1 39 i th t


This router sends an Auto-RP message to 224.0.1.39, announcing the router as a candidate RP for the groups in the range described by the access list.

Assigning the RP Mapping AgentAssigning the RP Mapping Agentrouter(config)#

ip pim send-rp-discovery {interface type} scope {ttl}

The RP mapping agent is the router that tells other routers which group to RP range to userouters 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 sourceAll routers within ttl number of hops from the source router receive the Auto-RP Discovery messages.


Dense Mode

Cisco recommends that you use Protocol Independent Multicast (PIM)sparse mode, particularly Auto-RP, where possible and especially fornew deployments. However, if dense mode is desired, configure theglobal command ip multicast-routing and the interface command ippim sparse-dense-mode on each interface that needs to processmulticast traffic.

As of Cisco IOS® Sotware Release 11.1, you can configure the interfacecommands ip pim dense-mode and ip pim sparse-modesimultaneously with the ip pim sparse-dense-mode command. In this

d th i t f i t t d d d if th i i dmode, the interface is treated as dense-mode if the group is in dense-mode. If the group is in sparse-mode (for example, if an RP is known),the interface is treated as sparse-mode.


Dense Mode

Note: The "Source" in the examples throughout this documentrepresents the source of multicast traffic, and "Receiver"

ip multicast-routing ip multicast-routing

represents the receiver of multicast traffic.

ip multicast routing

interface ethernet0 ip address <address> <mask> ip pim sparse-dense-mode

ip multicast routing

interface serial0 ip address <address> <mask> ip pim sparse-dense-mode




Sparse Mode with one RP

In this example, Router A is the RP which is typically the closest router tothe source. Static RP configuration requires that all routers in the PIMdomain have the same ip pim rp address commands configured You can

ip multicast-routing ip multicast-routing

domain have the same ip pim rp-address commands configured. You canconfigure multiple RPs, but there can only be one RP per specific group.

ip multicast routing ip pim rp-address 1.1.1.1

interface ethernet0 ip address <address> <mask> i i dd dd

ip multicast routing ip pim rp-address 1.1.1.1

interface serial0 ip address <address> <mask> i i dd ddip pim sparsesparse--densedense--modemode

interface serial0 ip address 1.1.1.1 255.255.255.0 ip pim sparsesparse--densedense--modemode

ip pim sparsesparse--densedense--modemode

interface ethernet0 ip address <address> <mask> ip pim sparsesparse--densedense--modemode


p p pp p p pp

Sparse Mode with Multiple RPs

In this example, Source-A sends to 224.1.1.1, 224.1.1.2, and 224.1.1.3. Source-B sends to224.2.2.2, 224.2.2.3, and 224.2.2.4. You could have one router, either RP 1 or RP 2, be the RPfor all groups. However, if you want different RPs to handle different groups, you need toconfigure all routers to include which groups the RPs will serve. This type of static RP


configure all routers to include which groups the RPs will serve. This type of static RPconfiguration requires that all routers in the PIM domain have the same ip pim rp-addressaddress acl commands configured. You can also use Auto-RP in order to achieve the samesetup, which is easier to configure.


ip pim RP-address 1.1.1.1 2i i RP dd 2 2 2 2 3ip pim RP-address 2.2.2.2 3

access-list 2 permit 224.1.1.1access-list 2 permit 224.1.1.2access-list 2 permit 224.1.1.3access list 2 permit 224.1.1.3

access-list 3 permit 224.2.2.2access-list 3 permit 224.2.2.3access-list 3 permit 224.2.2.4


ip pim RP-address 1.1.1.1 2ip pim RP-address 2.2.2.2 3

access-list 2 permit 224.1.1.1

ip multicast-routingip pim RP-address 1.1.1.1 2ip pim RP-address 2.2.2.2 3p

access-list 2 permit 224.1.1.2access-list 2 permit 224.1.1.3

access-list 3 permit 224.2.2.2li t 3 it 224 2 2 3

access-list 2 permit 224.1.1.1access-list 2 permit 224.1.1.2access-list 2 permit 224.1.1.3access list 3 permit 224 2 2 2


access-list 3 permit 224.2.2.3access-list 3 permit 224.2.2.4

access-list 3 permit 224.2.2.2access-list 3 permit 224.2.2.3access-list 3 permit 224.2.2.4

Auto-RP with one RP Auto-RP requires that you configure the RPs to announce theiravailability as RPs and mapping agents. The RPs use224 0 1 39 to send their announcements The RP mapping224.0.1.39 to send their announcements. The RP mappingagent listens to the announced packets from the RPs, thensends RP-to-group mappings in a discovery message that issent to 224 0 1 40sent to 224.0.1.40.

These discovery messages are used by the remaining routersf th i RP t Y RP th t lfor their RP-to-group map. You can use one RP that alsoserves as the mapping agent, or you can configure multipleRPs and multiple mapping agents for redundancy purposes.


Auto-RP with one RP

N h h h i f f hi hNote that when you choose an interface from which to sourceRP announcements, Cisco recommends that you use aninterface such as a loopback instead of a physical interface.

The loopback interface must be PIM-enabled and advertisedby an Interior Gateway Protocol (IGP), or it must be reachablewith static routing.


Auto-RP with one RP


ip pim send-rp-announce loopback0 scope 16 (RP) ip pim send-rp-discovery scope 16 (Mapping agent)


interface ethernet0 ip address <address> <mask> ip pim sparse dense mode

interface loopback0 ip address <address> <mask> ip pim sparse-dense-mode

ip pim sparse-dense-mode



interface serial0



Auto-RP with Multiple RPs

The access lists in this example allow the RPs to be an RP only for the groups you want. If noaccess list is configured, the RPs are available as an RP for all groups. If two RPs announceg , g ptheir availability to be RPs for the same group(s), the mapping agent(s) resolve these conflictswith "the highest IP address wins" rule.When two RPs announce for that group, you can configure each router with a loopbackaddress in order to influence which router is the RP for a particular group. Place the higher IPaddress on the preferred RP then use the loopback interface as the source of the announce


address on the preferred RP, then use the loopback interface as the source of the announcepackets; for example, ip pim send-RP-announce loopback0. When multiple mapping agentsare used, they each advertise the same group to RP mappings to the 224.0.1.40 discoverygroup.



interface loopback0ip address <address> <mask>pip pim sparse-dense-mode

ip pim send-RP-announce loopback0 scope 16 group-list 1ip pim send-RP-discovery scope 16


access-list 1 permit 239.0.0.0 0.255.255.255



interface loopback0ip address <address> <mask>pip pim sparse-dense-mode

ip pim send-RP-announce loopback0 scope 16 group-list 1ip pim send-RP-discovery scope 16


access-list 1 deny 239.0.0.0 0.255.255.255access-list 1 permit 224.0.0.0 15.255.255.255

Anycast RP MSDP Example The main purpose of an Anycast RP implementation is that the downstream multicast routers will “see”just one address for an RP. The example given shows how the loopback 0 interface of the RPs (RP1and RP2) is configured with the same 10.0.0.1 IP address.

If this 10.0.0.1 address is configured on all RPs as the address for the loopback 0 interface and thenconfigured as the RP address IP routing will converge on the closest RP This address must be a hostconfigured as the RP address, IP routing will converge on the closest RP. This address must be a hostroute - note the 255.255.255.255 subnet mask/32.

The downstream routers must be informed about the 10.0.0.1 RP address. In Figure, the routers areconfigured statically with the ip pim rp-address 10.0.0.1 global configuration command. Thisconfiguration could also be accomplished using the Auto-RP or bootstrap router (BSR) featuresconfiguration could also be accomplished using the Auto RP or bootstrap router (BSR) features.


V if iVerifying Multicast ConfigurationConfiguration


Inspecting Multicast Routing TableInspecting Multicast Routing Tablerouter#

Displays the contents of the IP multicast routing tableDi l li bb i t d f h t

show ip mroute [group-address] [summary] [count] [active kbps]

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

b f k t k t d k t i dnumber of packets, packets per second, average packet size, and bits per second.active: Displays the rate at which active sources are sending to

lti t A ti th di t tmulticast 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 mrouteshow ip mroute

NA-1#sh ip mrouteIP Multicast Routing TableFlags: 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 - URDX - Proxy Join Timer Running, A - Advertised via MSDP, U - URD,I - Received Source Specific Host Report

Outgoing interface flags: H - Hardware switchedTimers: Uptime/ExpiresInterface state: Interface, Next-Hop or VCD, State/Mode

(*, 224.1.1.1), 00:07:54/00:02:59, RP 10.127.0.7, flags: SIncoming interface: Null, RPF nbr 0.0.0.0Outgoing interface list:Serial1/3, Forward/Sparse, 00:07:54/00:02:32Serial1/3, Forward/Sparse, 00:07:54/00:02:32

(172.16.8.1, 224.1.1.1), 00:01:29/00:02:08, flags: TAIncoming interface: Serial1/4, RPF nbr 10.139.16.130Outgoing interface list:S i l1/3 F d/S 00 00 57/00 02 02


Serial1/3, Forward/Sparse, 00:00:57/00:02:02

Finding PIM NeighborsFinding PIM Neighborsrouter#

show ip pim interface [type number] [count]

Displays information about interfaces configured for PIM

show ip pim neighbor [type number]

router#

Lists the PIM neighbors discovered by the router

router#

mrinfo [hostname | address]

router#

Queries which neighboring multicast routers are peering with


g g p gthe local router or router specified

show ip pim interfaceshow ip pim interface

NA-2#show ip pim interfaceAddress Interface Ver/ Nbr Query DR DR

Mode Count Intvl Prior10 139 16 133 Serial0/0 v2/S 1 30 1 0 0 0 010.139.16.133 Serial0/0 v2/S 1 30 1 0.0.0.010.127.0.170 Serial1/2 v2/S 1 30 1 0.0.0.010.127.0.242 Serial1/3 v2/S 1 30 1 0.0.0.0


show ip pim neighborshow ip pim neighbor

NA-2#show ip pim neighborPIM Neighbor TableNeighbor Interface Uptime/Expires Ver DRAddress Priorityy10.139.16.134 Serial0/0 00:01:46/00:01:28 v2 None10.127.0.169 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)


Checking RP InformationChecking RP Informationrouter(config)#

Displays active RPs that are cached with associated multicast routing entries.

show ip pim rp [group-name | group-address | mapping]

gMapping—displays all group-to-RP mappings that the router is aware of

Displays how IP multicast routing does Reverse Path Forwarding

show ip rpf {source address | name }

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


information is displayedName—name of the host for which RPF information is displayed

show ip pim rpshow ip pim rp

P4-2#show ip pim rpGroup: 224.1.2.3, RP: 10.127.0.7, uptime 00:00:20, expires never

P4-2#show ip pim rp mappingPIM Group-to-RP Mappings

Group(s) 224.0.1.39/32RP 10.127.0.7 (NA-1), v1

Info source: local, via Auto-RPUptime: 00:00:21, expires: never

Group(s) 224.0.1.40/32RP 10.127.0.7 (NA-1), v1

Info source: local, via Auto-RPUptime: 00:00:21, expires: never

Group(s): 224.0.0.0/4, StaticRP: 10.127.0.7 (NA-1)


show ip rpfshow ip rpf

(towards the RP)NA-2#show ip rpf 10 127 0 7NA 2#show ip rpf 10.127.0.7RPF information for NA-1 (10.127.0.7)RPF interface: Serial1/3RPF neighbor: ? (10.127.0.241)RPF route/mask: 10 127 0 7/32RPF route/mask: 10.127.0.7/32RPF type: unicast (ospf 1)RPF recursion count: 0Doing distance-preferred lookups across tables

(towards the source)NA-2#show ip rpf 10.139.17.126RPF information for ? (10.139.17.126)RPF interface: Serial0/0RPF interface: Serial0/0RPF neighbor: ? (10.139.16.134)RPF route/mask: 10.139.17.0/25RPF type: unicast (ospf 1)RPF recursion count: 0


RPF recursion count: 0Doing distance-preferred lookups across tables

Checking the Group StateChecking the Group Staterouter#

show ip igmp interface [type number]

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


Configure a Router as a Group MemberConfigure a Router as a Group MemberRouter (config-if)#

ip igmp join-group group address

Configure a router to join a specific multicast group and enable IGMP on an interfaceenable IGMP on an interface.

ip igmp static-group group-addressRouter (config-if)#

ip igmp static group group address

Configures the router as a statically connected member of a groupg p


show ip igmp interfaceshow ip igmp interface

rtr-a>show ip igmp interface e0Ethernet0 is up, line protocol is upInternet address is 1.1.1.1, subnet mask is 255.255.255.0IGMP is enabled on interfaceIGMP is enabled on interfaceCurrent IGMP version is 2CGMP is disabled on interfaceIGMP query interval is 60 secondsIGMP querier timeout is 120 secondsIGMP querier timeout is 120 secondsIGMP max query response time is 10 secondsInbound IGMP access group is not setMulticast routing is enabled on interfaceMulticast TTL threshold is 0Multicast TTL threshold is 0Multicast 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


show ip igmp groupsshow ip igmp groups

rtr-a>sh ip igmp groupsIGMP Connected Group MembershipGroup Address Interface Uptime Expires Last Reporter224 1 1 1 Ethernet0 6d17h 00:01:47 1 1 1 12224.1.1.1 Ethernet0 6d17h 00:01:47 1.1.1.12224.0.1.40 Ethernet0 6d17h never 1.1.1.17


Verifying IGMP Snooping on a SwitchVerifying IGMP Snooping on a Switchswitch>

Displays information about multicast groups.If igmp keyword is used only IGMP learned information is shown

show multicast group [igmp] [mac_addr] [vlan_id]

If igmp keyword is used, only IGMP-learned information is shown.

switch>

Displays information on dynamically learned and manually configured multicast router ports

show multicast router [igmp] [mod_num/port_num] [vlan_id]

configured multicast router ports. If igmp keyword is used, only IGMP-learned information is shown.


Verifying IGMP Snooping ExampleVerifying IGMP Snooping—Example


Verifying IGMP Snooping—Example (Cont )

Switch> show igmp statistics 10IGMP enabled

(Cont.)

IGMP enabled

IGMP statistics for vlan 10:

IGMP statistics for vlan 10:Transmit:Transmit:

General Queries: 0Group Specific Queries: 0

Reports: 0Leaves: 0

Receive:General Queries: 1

Group Specific Queries: 0Reports: 2Leaves: 0Leaves: 0

Total Valid pkts: 4Total Invalid pkts: 0

Other pkts: 1MAC-Based General Queries: 0

Failures to add GDA to EARL: 0


Failures to add GDA to EARL: 0Topology Notifications: 0

Verifying IGMP Snooping—Example (Cont )

Switch> show multicast router igmp

(Cont.)

g pPort Vlan---------- ----------------4/1 10

Total Number of Entries = 1'*' - Configured 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 4/110 01-00-5e-01-02-03 4/1-2

Total Number of Entries = 2


ResourcesResources

Cisco IOS IP Multicast Configuration GuideCisco IOS IP Multicast Configuration Guidehttp://cisco.com/en/US/partner/products/ps6350/products_configuration_guide_book09186a0080435b9f.html

IP Multicast Deployment Fundamentalshttp://cisco.com/en/US/partner/tech/tk828/tech_brief09186a00800e9952.html

Multicast Quick-Start Configuration Guidehttp://cisco.com/en/US/partner/tech/tk828/technologies_tech_note09186a0080094821 shtmlte09186a0080094821.shtml

Basic Multicast Troubleshooting Toolshttp://cisco.com/en/US/partner/tech/tk828/technologies_tech_no

09186 0080093f21 h l


te09186a0080093f21.shtml

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