04-IGMP Snooping Configuration

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Operation Manual IGMP SnoopingQuidway S8500 Series Routing Switches Table of Contents

Huawei Technologies Proprietary

i

Table of Contents

Chapter 1 IGMP Snooping Configuration ................................................................................... 1-1

1.1 IGMP Snooping Overview ................................................................................................. 1-1

1.1.1 IGMP Snooping Principle........................................................................................ 1-1

1.1.2 IGMPv3 Snooping ................................................................................................... 1-2

1.1.3 Implementing IGMP Snooping ................................................................................ 1-4

1.2 IGMP Snooping Configuration Tasks ................................................................................ 1-7

1.2.1 Enabling IGMP Snooping........................................................................................ 1-7

1.2.2 Configuring IGMP Snooping Parameters................................................................ 1-8

1.2.3 Disabling Flooding of Unknown Multicast Packets in the VLAN............................. 1-9

1.2.4 Configuring an ACL for Filtering Multicast Groups................................................ 1-10

1.2.5 Configuring the Fast Leave Function.................................................................... 1-11

1.2.6 Static Router Port Configuration ........................................................................... 1-12

1.2.7 Configuring IGMP Snooping Multicast Data Load Balancing ............................... 1-13

1.2.8 Configuring an IGMP Snooping Querier ............................................................... 1-14

1.2.9 Configuring IGMP Report Replay Suppression .................................................... 1-16

1.3 Displaying and Maintaining IGMP Snooping ................................................................... 1-18

1.4 IGMP Snooping Configuration Example.......................................................................... 1-18

1.4.1 Enabling IGMP Snooping...................................................................................... 1-18

1.5 Troubleshooting IGMP Snooping..................................................................................... 1-19


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Operation Manual IGMP SnoopingQuidway S8500 Series Routing Switches Chapter 1 IGMP Snooping Configuration


1-1

Chapter 1 IGMP Snooping Configuration

When configuring IGMP Snooping, go to the following sections for the information you

are interested in:

IGMP Snooping Overview

IGMP Snooping Configuration Tasks

Displaying and Maintaining IGMP Snooping

IGMP Snooping Configuration Example

Troubleshooting IGMP Snooping

1.1 IGMP Snooping Overview1.1.1 IGMP Snooping Principle

Running at the data link layer, IGMP Snooping is a multicast control mechanism on the

Layer 2 Ethernet switch and it is used for multicast group management and control.

When receiving IGMP messages transmitted between the host and router, the Layer 2

Ethernet switch uses IGMP Snooping to analyze the information carried in the IGMP

messages. If the switch hears IGMP host report message from an IGMP host, it will add

the host to the corresponding multicast table. If the switch hears IGMP leave message

from an IGMP host, it will remove the host from the corresponding multicast table. Theswitch creates and maintains a MAC multicast address table at Layer 2 by continuously

listening to IGMP messages. After that, the switch can forward the multicast packets

transmitted from the upstream router according to the MAC multicast address table.

When IGMP Snooping is disabled, packets are broadcasted at Layer 2. See the

following figure:

Video stream

VOD Server

Layer 2 Ethernet Switch

Video stream

Multicast group

member

Non-multicastgroup member

Multicast router

Video

stream

Video

stream

Video

stream


Internet/Intranet

Figure 1-1 Multicast packet transmission without IGMP Snooping


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When IGMP Snooping runs, packets are multicast rather than broadcast at Layer 2.

See the following figure:

Video stream

VOD Server

Layer 2 Ethernet Switch

Video stream

Multicast group

member


Multicast router

Video

stream

Video

stream

Video

stream


Internet/Intranet

Figure 1-2 Multicast packet transmission when IGMP Snooping runs

1.1.2 IGMPv3 Snooping

I. IGMPv3 overview

In addition to compatibility with and inheritance from IGMPv1 and IGMPv2, IGMPv3

provides an enhanced host control capability. A host can not only join a designated

multicast group but also specify to receive information from a designated multicast

source.

Note:

S8500 series switches support IGMPv1 and IGMPv2, but they do not support IGMPv3

currently.

IGMP queries fall into general queries and group-specific queries. This section mainly

introduces IGMPv3 messages that are different from in IGMPv2.

1) Query messages

The following figure shows the differences between IGMPv2 and IGMPv3 query

messages:

The size of an IGMPv2 general query is eight bytes and that of an IGMPv3 general

query is twelve bytes.

The size of an IGMPv 2 group-specific query is eight bytes and that of an IGMPv3

general query is equal to or greater than twelve bytes.

The size of an IGMPv3 source-and-group-specific query is greater than twelve

bytes.


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type = 0x11

Checksum

Group Address

Max Resp Time

IGMPv2 query

type = 0x11

Checksum

Group Address

Source Address[1].

..Source Address[N]

Resv S QRV

QQIC

Number of Source(N)

Max Resp Code

IGMPv3 query

type = 0x11

Checksum

Group Address

Max Resp Time

IGMPv2 query

type = 0x11

Checksum

Group Address

Source Address[1].

..Source Address[N]

Resv S QRV

QQIC

Number of Source(N)

Max Resp Code

IGMPv3 query

Figure 1-3 Message formats of IGMPv2 and IGMPv3 queries

2) Membership report message

The following figure shows the differences between IGMPv2 and IGMPv3 membership

report messages:

The type field of an IGMPv2 membership report is set to 0x16.

IGMPv2 cannot recognize IGMPv3 membership report messages.

Upon receiving an IGMPv3 report, the device transmits the IGMPv3 query

transparently in the VLAN and converts it into an IGMPv2 report for further

processing.


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type = 0x16

Checksum

Group Address

0x00

IGMPv2 membership report

Record Type1...6

Number of

Sources(N)

Multicast Address

Source Record[1].

.

.

Source Record[N]

Aux Data Len

Auxiliary Data

type = 0x22

Checksum

Reserved

Group Recoed[1]

.

.

.Group Record[M]

Number of Group

Records(M)

Reserved


type = 0x16

Checksum

Group Address

0x00


Record Type1...6

Number of

Sources(N)

Multicast Address

Source Record[1].

.

.

Source Record[N]

Aux Data Len

Auxiliary Data

type = 0x22

Checksum

Reserved

Group Recoed[1]

.

.

.Group Record[M]

Number of Group

Records(M)

Reserved


Figure 1-4 Message formats of IGMPv2 and IGMPv3 membership reports

II. Message processing in IGMPv3 Snooping on an S8500 switch

Note:

Currently, the device supports only the INCLUDE mode of source filtering in IGMPv3

reports, that is, IGMPv3 report messages are converted to IGMPv2 reports except

those with the filtering mode set to include { NULL }, which are converted to IGMPv2

leave messages.

With IGMPv3 Snooping enabled, upon receiving an IGMPv3 query, the device

transmits the IGMPv3 query transparently in the VLAN and then converts it into an

IGMPv2 report for further processing.

1.1.3 Implementing IGMP Snooping

I. Concepts related to IGMP Snooping

To facilitate the description, this section first introduces some concepts related to IGMP

Snooping.

Router Port: The port that connects the switch to a multicast router and resides on

the switch, instead of the router.

Multicast member port: The Ethernet switch port connected to a multicast member.

The multicast member refers to a host joined a multicast group.


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MAC multicast group: The multicast group is identified by MAC multicast address

and maintained by the Ethernet switch.

Router port aging time: Time set on the router port aging timer. If the switch has

not received any IGMP general query message when the timer expires, itconsiders the port no longer as a router port.

Multicast group member port aging time: When a port joins an IP multicast group,

the aging timer of the port is started. The multicast group member port aging time

is set on this aging timer. If no IGMP report or PIM hello message reaches the port

when the timer expires the switch sends a multicast group-specific query message.

When the maximum response time expires, if no IGMP report reaches the port, the

switch judges that the port is no longer a member port.

Maximum response time: When the switch transmits IGMP group-specific query

message to the multicast member port, the Ethernet switch starts a response timer.

The maximum response time refers to the timer length. If the switch has not

received any IGMP report message before the timer expires, it will remove the port

from the multicast member ports.

II. Implementing Layer 2 multicast with IGMP Snooping

The Ethernet switch runs IGMP Snooping to listen to IGMP messages and map the

host and its ports to the corresponding multicast group address. To implement IGMP

Snooping, the Layer 2 Ethernet switch processes different IGMP messages in the way

illustrated in the figure below:

IGMP

messageAn Ethernet switch

running IGMP

Snooping

IGMP

message

A router

running IGMP

Internet

Figure 1-5 Implement IGMP Snooping

1) IGMP general query message: Transmitted by the multicast router to the multicast

group members to query which multicast group contains a member. When an

IGMP general query message arrives at the router port, the Ethernet switch will

reset the aging timer of the port. When a port other than the router port receives

the IGMP general query message, the Ethernet switch will start the aging timer for

the port.


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2) IGMP group-specific query message: IGMP group-specific query messages are

used to find out whether a particular group still has members on the local subnet.

Upon hearing an IGMP group-specific query message, the switch sends the

group-specific query message only to the multicast group being queried.3) IGMP report message: IGMP report messages are sent by hosts to the multicast

router to join multicast groups or report their group memberships in response to

IGMP query messages. Upon hearing an IGMP report message, the switch

checks whether the MAC multicast group corresponding to the reported IP

multicast group exists and proceeds accordingly.

If the MAC multicast group does not exist, the switch notifies the router that a

member is ready to join the reported multicast group, creates a new MAC-based

forwarding entry, adds the port that received the report message to the entry,

starts an aging timer for the port, and then adds all the router ports in the native

VLAN of the port into the MAC multicast forwarding table.

If the corresponding MAC multicast group exists but does not contain the port

received the report message, the switch adds the port into the multicast group and

starts the port aging timer.

If the MAC multicast group exists and contains the port that received the message,

the switch will only reset the aging timer of the port.

4) IGMP leave message: Transmitted from the multicast group member to the

multicast router to notify that a host left the multicast group. Upon hearing a leave

message for an IP multicast group, the Ethernet switch sends a group-specific

query message for that group to the port on which it heard the message, to check

whether any other active members for that group are attached to the port, and

meanwhile starts a maximum response timer. If the switch receives no report

message for that multicast group before the timer expires, the port will be removed

from the corresponding MAC-based forwarding table entry. If the switch has no

more member ports for that MAC multicast group, the switch will notify the

upstream multicast router to prune the branch off the multicast distribution tree.

Note:

You can configure a port of a Layer 2 switch as a multicast group member to

respond to an IGMP query message of a multicast router, so as to prevent the

multicast router from canceling the corresponding path if there is no multicast

member in the current network segment. For details, refer to the part of configuring

a router to join a multicast group in IGMP Configuration.

By default, ports of a Layer 2 switch do not belong to any multicast group. Note that,

the specified port must belong to an IGMP Snooping-enabled VLAN. Otherwise, the

configuration will not work.


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1.2 IGMP Snooping Configuration Tasks

Enabling IGMP Snooping

Configuring IGMP Snooping Parameters

Disabling Flooding of Unknown Multicast Packets in the VLAN

Configuring an ACL for Filtering Multicast Groups

Configuring the Fast Leave Function

Static Router Port Configuration

Configuring IGMP Snooping Multicast Data Load Balancing

Configuring an IGMP Snooping Querier

Configuring IGMP Report Replay Suppression

1.2.1 Enabling IGMP Snooping

You can control the creation and maintenance of MAC multicast tables at Layer 2 by

enabling IGMP Snooping.

I. Configuration prerequisites

Make sure Layer 2 and Layer 3 multicast protocols are not enabled in the same

VLAN or on the same VLAN interface.

VLAN VPN is disabled in the VLAN.

II. Configuration procedure

Follow these steps to enable IGMP Snooping:

To do... Use the command... Remarks

Enter system view system-view

Enable IGMP Snoopingigmp-snooping {enable|disable}

Required

IGMP Snooping isdisabled by default.

Enter VLAN view vlan vlan-id

Enable IGMP Snooping

igmp-snooping {enable

|disable}

Required

IGMP Snooping isdisabled by default.

Display IGMP Snoopingconfiguration

display igmp-snoopingconfiguration

The display commandcan be executed in anyview.


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Caution:

Before configuring IGMP Snooping, first enable it globally in system view and then

enable it in VLAN view. Otherwise, the configuration will not work.

IGMP Snooping is applicable to isolate-user VLANs. If IGMP Snooping is enabled in

an isolate-user VLAN, it is enabled in all the secondary VLANs. Therefore, enabling

IGMP Snooping in a secondary VLAN is not necessary.

The IGMP packets in a secondary VLAN are processed in the isolate-user VLAN.

That is, for a user-isolate VLAN, all the multicast services are processed in the

isolate-user VLAN.

A port in a secondary VLAN cannot be used for receiving multicast traffic.

1.2.2 Configuring IGMP Snooping Parameters

IGMP Snooping parameters include:

Router port aging time

Maximum response time

Multicast group member port aging time


IGMP Snooping is enabled globally.


Perform the following operations to configure IGMP Snooping parameters:



Configure router portaging time

igmp-snoopingrouter-aging-timeseconds

Optional

By default, the route portaging time is 260 seconds

Configure maximumresponse time

igmp-snoopingmax-response-timeseconds

Optional

By default the maximumresponse time is 1 second

Configure multicast groupmember port aging time

igmp-snoopinghost-aging-time seconds

Optional

By default, the multicastgroup member port agingtime is 260 seconds.


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1.2.3 Disabling Flooding of Unknown Multicast Packets in the VLAN

If neither IGMP Snooping nor Layer 3 multicast is enabled in a VLAN, unknown

multicast packets are flooded in the VLAN. Therefore, to disable unknown multicast

packets from being flooded in a VLAN, you need to enable IGMP Snooping in the VLAN

and execute the igmp-snooping nonflooding-enablecommand.


IGMP Snooping is enabled in the VLAN.


For a general board

Follow these steps to disable flooding of unknown multicast packets in the VLAN on a

general board:



Disable flooding ofunknown multicastpackets in the VLAN

igmp-snoopingnonflooding-enable

By default, multicastpackets are flooded in aVLAN.

For a special board

Follow these steps to disable flooding of unknown multicast packets in the VLAN on a

special board:



Disable flooding ofunknown multicastpackets in multiple VLANson the 10GE boards

igmp-snooping10ge-non-floodingenable slot slot-num

By default, 10GE boardsdo not supportnon-flooding of unknownmulticast packets.

Disable flooding of

unknown multicastpackets in the VLAN

igmp-snooping

nonflooding-enable

By default, multicast

packets are flooded in theVLAN

Display the configurationinformation

displaycurrent-configuration

The display commandcan be executed in anyview


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Caution:

The configuration listed in the above table is recommended for 10 GE ports on

LSB1XP2B0, LSB1XK1B0, and LSB1TGX1B0 boards (including 110 GE and 210

GE boards) only when Layer 2 multicast is not flooded in multiple VLANs and

inter-board and intra-board forwarding are not required.

After you perform the configuration successfully, the board restarts automatically

and your configuration will take effect.

When the board is not in position, the commands do not take effect.

1.2.4 Configuring an ACL for Filtering Multicast Groups




Follow these steps to configure an ACL for filtering multicast groups:




Apply an ACL forfiltering multicastgroups in the VLAN

igmp-snoopinggroup-policyacl-number

Required

By default, the ACL for filteringmulticast groups is not configuredin a VLAN. In this case, a host canjoin any multicast group.

After the ACL for filtering multicastgroups is configured, the multicastgroups that are not permitted bythe ACL cannot be created.


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Caution:

If the ACL applied to a VLAN does not exist or contain any rule, the host cannot join

any multicast group.

The rules of the ACL for filtering multicast groups are not limited by the ACL. This

function applies to all the members in the specified VLAN.

The rules for filtering multicast groups take effect only when the configuration policy

bound to the ACL number exists.

The rules for filtering multicast groups have no effect on locally configured static

multicast groups.

1.2.5 Configuring the Fast Leave Function




Follow these steps to configure the fast leave function:



Enable the fast leavefunction

igmp-snoopingfast-leave[ vlan { vlan-id[ tovlan-id] } & ]

This function is disabledby default.

Enter Ethernet port viewinterface interface-typeinterface-number

Enable the fast leavefunction

igmp-snoopingfast-leave[ vlan { vlan-id[ tovlan-id] } & ]

This function is disabledby default

Note:

The fast leave configuration performed in system view and that performed in port view

are independent of each other. That is, the configuration performed in system view is

effective to all the ports in the specified VLAN, whereas the configuration performed in

port view is effective for the port in the specified VLAN. For example, a trunk port

belongs to multiple VLANs.


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Caution:

The fast leave function cannot take effect if the specified VLAN does not exist, the

port does not belong to the specified VLAN, or IGMP Snooping is not enabled in the

VLAN.

If you enable IGMP Snooping again, the original configuration of fast leave will be

cleared.

You cannot configure this command when IGMP Snooping is not enabled globally.

(You can use the igmp-snooping enablecommand in system view to enable IGMP

Snooping globally.)

For an aggregation port, the fast leave function only takes effects on the master

aggregation port.

If an IGMPv1 host in the same group joins the port, even if fast leave is enabled on

the port, it does not take effect.

1.2.6 Static Router Port Configuration

By configuring a port in a VLAN to be a static router port, you can enable IGMP packets

to be transparently transmitted through the port, meeting the requirements of specific

networks.

I. Prerequisites

The port and VLAN involved already exist.

The port to be configured belong to the corresponding VLAN.

II. Configuring a static router port

Follow these steps to configure a port in a VLAN to be a static router port in VLAN view:




Configure a staticrouter port

multicaststatic-router-portport-number

Theport-number argument is in theformat of interface-typeinterface-number, where theinterface-typeargument can onlybe Ethernet port type.

By default, no static router port isconfigured.


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Follow these steps to configure a port in a VLAN to be a static router port in Ethernet

port view:



Enter Ethernet port viewinterface interface-typeinterface-number

The interface-typeargument can only beEthernet port type.

Configure a static routerport

multicaststatic-router-portvlanvlan-id

By default, no static routerport is configured.

Caution:

You will fail to configure a port to be a static router port if the port identified by the

port-numberargument does not exist, or the port does not belong to the VLAN.

You will fail to configure a port to be a static router port if the VLAN identified by the

vlan-id argument does not exist or the port does not belong to the VLAN.

You can configure multiple ports in a VLAN to be static router ports by performing

the above configuration repeatedly. The newly configured ports do not overwrite the

existing static router ports.

When a trunk port belongs to multiple VLANs, this port can be configured as the

static router port for multiple VLANs.

Static router ports can be configured in VLAN view or Ethernet port view. However,

you can verify the configured static router ports only by executing thedisplay this

command in Ethernet port view.

The configuration of a static router port takes effect on the current port only, no

matter whether the current port is an aggregated port or not. To configure all ports in

an aggregation group as static router ports, you can enable the static router port

function on all the ports in the aggregation group.

The static router port is valid when IGMP Snooping, IGMP, PIM-DM or PIM-SM is

enabled in the VLAN.

1.2.7 Configuring IGMP Snooping Multicast Data Load Balancing

After IGMP Snooping is enabled in a VLAN, multicast packets will be flooded in the

VLAN if no port has joined the destination multicast group. With IGMP Snooping

non-flooding enabled, data packets are not flooded in the VLAN but are forwarded to

router ports if no member port for the destination multicast group exists. Since multicast

routers send IGMP query and PIM Hello messages periodically, the switch can


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recognize which ports are router ports. If neither member ports nor router ports exist,

multicast packets are dropped.

When a user joins a multicast group, the device deletes the original multicast MAC

address created by IGMP-snooping non-flooding and creates a new IGMP-snoopingmulticast MAC address. With the IGMP Snooping non-flooding function enabled, if any

router port is in an aggregation group, the system can evenly distribute unknown

multicast traffic to different aggregation ports according to the hash algorithm, thus

implementing load balancing of multicast traffic.

Follow these steps to configure IGMP Snooping multicast non-flooding:



Enable IGMP Snooping igmp-snooping enable Required

Enable IGMP Snoopingnon-flooding

igmp-snoopingnonflooding-enable

Required

Configure aging time pointfor IGMP Snoopingnon-flooding entries

igmp-snoopingnon-floodingentry-age-timeHH:MM:SS

Optional

Display the configurationinformation


The display commandcan be executed in anyview

Caution:

When you enable IGMP Snooping non-flooding, a aging time point is configured.

The default aging time point is 3:00:00.

After you disable IGMP Snooping or IGMP Snooping non-flooding, the aging time

point is invalidated at the same time.

1.2.8 Configuring an IGMP Snooping Querier

IGMP Snooping runs on Layer 2 switches connecting with users and layer-3 devices.

Layer-3 devices send general queries to maintain membership in the local subnet. The

IGMP Snoopingenabled device maintains Layer 2 multicast forwarding tables by

listening to IGMP messages. Where Layer 2 multicast is implemented without the need

of Layer-3 devices, IGMP Snooping queriers can establish and maintain multicast

forwarding tables.

IGMP Snooping queriers are used in Layer 2only multicast networks.


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IGMP general query

IGMP report

Multicast sourceSwitch

(IGMP Snooping)

Receiver

Receiver

IGMP general query

Figure 1-6 Implement IGMP Snooping query

IGMP Snooping querier configuration tasks include:

Enabling IGMP Snooping Configuring the interval at which the IGMP Snooping querier sends general

queries in a VLAN

Configuring a maximum response time of IGMP general queries in a VLAN

Configuring the source IP address the IGMP Snooping querier uses to send

general query messages in a VLAN

Configuring an IGMP Snooping querier


Layer 2 and Layer 3 multicast protocols cannot be enabled in the same VLAN or

on the same VLAN interface.

VLAN VPN is disabled in the VLAN.

VLAN VPN-enabled ports are not added into this VLAN.


Follow these steps to configure an IGMP Snooping querier:



Enable IGMP Snooping igmp-snooping{enable |disable}

RequiredThis function is disabled bydefault.


Enable IGMP Snoopingigmp-snooping{enable |disable}

Required

This function is disabled bydefault.

Configure the interval atwhich the IGMP Snoopingquerier sends generalqueries in the VLAN

igmp-snoopingquery-intervaltime-interval

Optional

By default, the queryinterval is 60 seconds.


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Configure a maximum

response time

igmp-snooping

max-response-timemax-response-time

Optional

By default, the maximum

response time of an IGMPquery message is 10seconds.

Configure a source IPaddress of general querymessages

igmp-snoopinggeneral-querysource-ip{ current-interface|ip-address}

Optional

By default, the source IPaddress is 0.0.0.0.

Enable IGMP Snoopingquerier

igmp-snooping querier

Required

By default, IGMP Snoopingquerier is not enabled in a

VLAN.

Display the IGMPSnooping configurationinformation in a VLAN

display igmp-snoopingconfiguration vlanvlan-id

The display command canbe executed in any view.

Note:

The default source IP address of IGMP general queries is 0.0.0.0. If you configure

the IGMP Snooping querier to use the primary IP address of the current VLAN

interface as the source IP address of IGMP general queries and the device fails to

obtain the primary IP address of the virtual interface, the default source IP address,

namely, 0.0.0.0, will be used. For compatibility with devices that do not support

general messages with the source IP address 0.0.0.0, you need to configure the

source IP address manually.

If you need to configure multiple queriers, it is advisable that you configure a longer

query interval to prevent deterioration of device performance caused by too many

IGMP general queries.

1.2.9 Configuring IGMP Report Replay Suppression

If IGMP Snooping relays (namely, forwards without any change) every IGMP report

message it hears on an IGMP-Snooping-enabled VLAN interface immediately to router

ports in the VLAN, the upstream device may suffer from a big burden. Therefore, IGMP

report relay needs to be suppressed in an IGMP-Snooping-enabled VLAN.


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With the IGMP report relay suppression function enabled, within each query cycle, the

Layer 2 device relays only the first IGMP report per multicast group to the Layer 3

device and will not relay the subsequent IGMP reports for the same multicast group to

the Layer 3 device. This helps reduce the number of packets being transmitted over thenetwork.

Note:

Currently, S8500 series switches do not support suppression of IGMPv3 messages.

The IGMP report relay suppression feature is effective only for a VLAN with IGMP

Snooping enabled.



II. Enabling IGMP report transparent transmission suppression

Follow these steps to enable IGMP report transparent transmission suppression:



Enable IGMP Snooping igmp-snooping enable Required

Enable IGMP reporttransmission suppression

igmp-snoopingreport-aggregation

Required

By default, this function isdisabled.

Display the IGMPSnooping configurationinformation in systemview


The display commandcan be executed in anyview.


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1.3 Displaying and Maintaining IGMP Snooping


Display the informationabout current IGMPSnooping configuration


Display IGMP Snoopingstatistics of received andsent messages

display igmp-snooping statistics

Display IP/MAC multicastgroup information in aVLAN

display igmp-snooping group[ vlanvlan-id [group-address]]

Enable IGMP Snooping

debugging

debugging igmp-snooping{abnormal| all| events| forward|

groups| packets|timers }

Available in anyview

Clear IGMP Snoopingstatistics information

reset igmp-snooping statisticsAvailable inuser view

1.4 IGMP Snooping Configuration Example

1.4.1 Enabling IGMP Snooping

I. Network requirements

As shown in Figure 1-7, to implement Layer 2 multicast delivery, IGMP Snooping needs

to be enabled on the switch deployed between the PCs.

II. Network diagram

Switch

Router

Multicast

Internet

Figure 1-7 Network diagram for IGMP Snooping configuration


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III. Configuration procedure

Suppose you need to enable IGMP Snooping on VLAN 10. The configuration

procedure is as follows:

# Display the current state of IGMP Snooping.

display igmp-snooping configuration

# If IGMP Snooping is not enabled, enable it in system view.

system-view

System View: return to User View with Ctrl+Z.

[Quidway] igmp-snooping enable

# Display the status of VLAN-interface 10, to check if PIM or IGMP is enabled on this

interface.

[Quidway] display current-configuration interface vlan-interface 10

# Enable IGMP Snooping in VLAN view only if PIM or IGMP is not running on VLAN 10

(IGMP Snooping can be enabled in a VLAN only if PIM and IGMP are not running in the

VLAN).

[Quidway] vlan10

[Quidway-vlan10] igmp-snooping enable

1.5 Troubleshooting IGMP Snooping

Symptom: The multicast function cannot be implemented on the switch.

Analysis and solutions:

1) IGMP Snooping is disabled.

Carry out the display current-configurationcommand in any view to display the

status of IGMP Snooping.

If IGMP Snooping is not enabled, carry out the igmp-snooping enablecommand

in system view to enable IGMP Snooping. Then, use the same command in VLAN

view to enable IGMP Snooping in the corresponding VLAN.

2) Multicast forwarding table set up by IGMP Snooping is incorrect.

Carry out the display igmp-snooping groupcommand in any view to display ifthe multicast group is the expected one.

If the multicast group created by IGMP Snooping is not correct, contact

maintenance personnel for help.

Continue with diagnosis 3 if the second step is completed.

3) Multicast forwarding table set up at the bottom layer is incorrect.

In any view, carry out the display mac-address vlan command to check whether

the MAC multicast forwarding table established at the bottom layer by vlan-id is

consistent with that established by IGMP Snooping.

If they are not consistent, contact the maintenance personnel for help.

04-IGMP Snooping Configuration

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