Contents

10  IGMP Snooping Configuration

10.1  IGMP Snooping Overview

10.2  IGMP Snooping Features Supported by the Switch

10.3  Default Configuration

10.4  Configuring Basic IGMP Snooping Functions

10.4.1  Enabling IGMP Snooping

10.4.2  Configuring the IGMP Snooping Version

10.4.3  (Optional) Configuring a Static Router Port

10.4.4  (Optional) Configuring a Static Member Port

10.4.5  (Optional) Configuring an IGMP Snooping Querier

10.4.6  (Optional) Suppressing Report and Leave Messages

10.4.7  (Optional) Configuring the Router-Alert Option

10.4.8  (Optional) Disabling Users from Dynamically Joining Multicast Groups

10.4.9  Checking the Configuration

10.5  Configuring IGMP Snooping Proxy

10.6  Configuring the IGMP Snooping Policy

10.6.1  Configuring a Multicast Group Policy

10.6.2  Filtering Multicast Data on an Interface

10.6.3  Discarding of Unknown Multicast Flows

10.6.4  Checking the Configuration

10.7  Configuring Membership Fast-Update

10.7.1  Setting the Aging Time of Group Member Ports

10.7.2  Setting the Aging Time of Dynamic Router Ports

10.7.3  Configuring Fast Leave for Member Ports

10.7.4  Sending IGMP Query Messages upon Topology Changes

10.7.5  Deleting IGMP Snooping Entries of DHCP Snooping Users Immediately After the Users Go Offline

10.7.6  Checking the Configuration

10.8  Configuring IGMP Snooping SSM Mapping

10.8.1  (Optional) Configuring an SSM Group Policy

10.8.2  Configuring IGMP Snooping SSM Mapping

10.8.3  Checking the Configuration

10.9  Maintaining IGMP Snooping

10.9.1  Clearing IGMP Snooping Entries

10.9.2  Clearing IGMP Snooping Statistics

10.9.3  Displaying the IGMP Snooping Running Status

10.10  Configuration Examples

10.10.1  Example for Configuring IGMP Snooping

10.10.2  Example for Configuring Layer 2 Multicast Through Static Interfaces

10.10.3  Example for Configuring an IGMP Snooping Querier

10.10.4  Example for Configuring IGMP Snooping Proxy

10.10.5  Example for Configuring IGMP Snooping SSM Mapping

10.11  Common Misconfigurations

10.11.1  Layer 2 Multicast Packets Cannot Be Forwarded

10.11.2  The Multicast Group Policy Does Not Take Effect

10  IGMP Snooping Configuration

IGMP snooping enables a Layer 2 multicast device to create and maintain a Layer 2 multicast forwarding table by analyzing IGMP messages exchanged between the upstream Layer 3 device and user hosts. This technology implements on-demand multicast data transmission at the data link layer.

Precautions

If an interface is used as an VPLS AC-side interface and a multicast inbound interface at the same time, multicast data cannot be forwarded normally on this interface.

10.1  IGMP Snooping Overview

Internet Group Management Protocol Snooping (IGMP snooping) is a Layer 2 IPv4 multicast protocol. The IGMP snooping protocol maintains information about the outgoing interfaces of multicast packets by snooping multicast protocol packets exchanged between the Layer 3 multicast device and user hosts. The IGMP snooping protocol manages and controls the forwarding of multicast packets at the data link layer.

IGMP Snooping

On an IPv4 multicast network, after receiving multicast packets from an upstream device, a device at the edge of the access layer forwards the multicast packets to user hosts. Therefore, the users can receive on-demand programs. As shown in Figure 10-1, by default, multicast packets are broadcast at the data link layer, causing bandwidth waste.

After IGMP snooping is configured on a Layer 2 device (such as the Switch in Figure 10-1), the Switch snoops Internet Group Management Protocol (IGMP) messages exchanged between an upstream device and downstream hosts and creates a Layer 2 multicast forwarding table. This implements on-demand multicast data transmission at the data link layer.

Figure 10-1  Multicast packet transmission before and after IGMP snooping is configured on a Layer 2 device

IGMP Snooping Benefits

A device configured with IGMP snooping forwards multicast data only to the specified receivers. It has the following advantages:
  • Reducing broadcast packets on Layer 2 networks to conserve network bandwidth
  • Forwarding multicast packets on Layer 2 networks to improve information security

10.2  IGMP Snooping Features Supported by the Switch

This section describes the IGMP snooping features supported by the switch: basic IGMP snooping functions, IGMP snooping proxy, IGMP snooping policy, membership fast-update and IGMP snooping SSM mapping.

NOTE:

Because IGMP snooping is a Layer 2 multicast feature, all the IGMP snooping configurations on interfaces mentioned in this chapter are performed on Layer 2 physical interfaces, including Eth-Trunk interfaces.

Basic IGMP Snooping Functions

The switch supports VLAN-based IGMP snooping. You can set the following parameters or functions of IGMP snooping:

  • IGMP Snooping versions, including IGMPv1, IGMPv2, and IGMPv3. The same IGMP version needs to be configured on the switch and an upstream Layer 3 device because the IGMP messages vary based on version.
  • Statically configuring router ports and member ports. This implements fast and stable forwarding of multicast data.
  • IGMP snooping querier. When IGMP querier is not enabled on an upstream device, the switch can substitute the upstream device to send IGMP Query messages.
  • IGMP snooping message suppression. This function limits the number of IGMP Report and Leave messages sent by member hosts to the upstream device and improves system performance.
  • Router-Alert. This function improves device performance and network security.
  • Disabling users from dynamically joining multicast groups. The IGMP Report and Leave messages received in a VLAN cannot be forwarded to the upstream device that has static multicast groups configured.

IGMP Snooping Proxy

When IGMP snooping proxy is enabled on a Layer 2 device, this device is enabled with both the message suppression and IGMP querier functions. The switch configured with IGMP snooping proxy functions as a host for its upstream device and a querier for its downstream host.

IGMP Snooping Policy

The switch can be configured to filter multicast data according to network requirements. You can perform the following configurations on the switch:
  • Configure a multicast group policy to control the multicast groups that users can join.
  • Configure multicast data filtering on an interface to reject the multicast data from specified VLANs.
  • Discard unknown multicast packets, preventing them from being broadcast in VLANs.

Membership Fast-Update

With this function, the switch can rapidly update memberships when a multicast group member joins or leaves a multicast group. This improves the efficiency and user experience of multicast services. You can set the following parameters or functions:

  • Sets the aging time of dynamic member ports.
  • Sets the aging time of dynamic router ports.
  • Configures fast leave for member ports.
  • Sends IGMP Query messages upon changes on a Layer 2 network topology.
  • Deletes IGMP snooping entries of DHCP snooping users immediately after the users go offline.

IGMP Snooping SSM Mapping

Source-Specific Multicast (SSM) allows multicast members to receive multicast data from the specified multicast sources. Only IGMPv3 supports the SSM model. Configure IGMP snooping SSM mapping on the switch to set up one-to-one mappings between multicast groups and multicast sources. The switch can then convert (*, G) entries in IGMPv1 or IGMPv2 messages to (S, G) entries to provide the SSM service for the hosts that run IGMPv1 or IGMPv2.

IGMP Snooping CPCAR Precautions

CPCAR limits the rate of protocol packets of different services sent to the control plane, ensuring security of the control plane. The device can set the default CPCAR values for the packets of each protocol. The CPCAR values of some protocol packets need to be adjusted based on the actual service scale and user network.

If the CPCAR values are adjusted improperly, network services are affected. To adjust the CPCAR values of IGMP packets, contact Huawei technical support engineers.

10.3  Default Configuration

This section provides the default IGMP snooping configuration.

Table 10-1  Default IGMP snooping configuration

Parameter

Default Setting

IGMP snooping

Disabled

IGMP snooping version

IGMPv2 when IGMP snooping is enabled

Multicast data forwarding mode in a VLAN

IP address based forwarding

IGMP snooping interface learning

Enabled when IGMP snooping is enabled

IGMP snooping querier

Disabled

IGMP snooping general query interval

60s

IGMP snooping message suppression

Disabled

IGMP snooping proxy

Disabled

IGMP snooping SSM mapping

Disabled

10.4  Configuring Basic IGMP Snooping Functions

Basic IGMP snooping functions enable a device to create and maintain a Layer 2 multicast forwarding table and implement on-demand multicast data transmission at the data link layer.

Pre-configuration Tasks

A VLAN has been created.

Configuration Process

10.4.1 Enabling IGMP Snooping and 10.4.2 Configuring the IGMP Snooping Version are mandatory and other tasks are optional.

10.4.1  Enabling IGMP Snooping

Context

Other IGMP snooping functions can be configured only after IGMP snooping is enabled globally. Other IGMP snooping functions take effect in a VLAN only after IGMP snooping is enabled in the VLAN.

By default, IGMP snooping is disabled globally on the switch.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. (Optional) Run:

    assign multicast-resource-mode optimize

    The multicast replication capability of LPUs is improved.

    If each multicast packet needs to be replicated into more than 8192 copies, run this command to improve the multicast replication capability before enabling IGMP Snooping.

  3. Run:

    igmp-snooping enable

    IGMP snooping is enabled globally.

  4. Run:

    vlan vlan-id

    The VLAN view is displayed.

  5. (Optional) Run:

    l2-multicast forwarding-mode { ip | mac }

    The multicast packets in the VLAN are forwarded based on IP addresses or MAC addresses.

    By default, multicast flows are forwarded based on IP addresses.

    NOTICE:
    • Configure the forwarding mode of multicast flows in the VLAN before IGMP snooping is enabled in the VLAN. Enable IGMP snooping in the VLAN for the configuration to take effect.

    • If the device forwards multicast data packets based on MAC addresses, do not use a group address on the network if the group address maps to the same multicast MAC address as a multicast IP address reserved for a protocol. Otherwise, the protocol that uses the multicast IP address cannot run normally. For example, OSPF uses 224.0.0.5 to send protocol packets. This multicast IP address maps to multicast MAC address 01-00-5E-00-00-05. If multicast data packets are forwarded based on MAC addresses and use multicast IP address 225.0.0.5 (also mapping to 01-00-5E-00-00-05), the OSPF protocol cannot run normally.

    NOTE:

    If the VLANIF interface corresponding to a VLAN is bound to a VPN instance but IGMP or PIM is disabled on this interface, multicast flows in this VLAN can only be forwarded based on the MAC addresses. To forward multicast flows in the VLAN based on the IP addresses, configure this VLAN as a user VLAN and another VLAN as a multicast VLAN. In this way, multicast flows can be replicated to the user VLAN from the multicast VLAN.

  6. (Optional) Run:

    l2-multicast router-port-discard

    The switch is disabled from forwarding multicast data to router ports in a VLAN.

    NOTICE:

    Before disabling the switch from forwarding multicast data to router ports in a VLAN, disable IGMP snooping in the VLAN. After setting the forwarding mode, enable IGMP snooping in the VLAN for the configuration to take effect.

  7. Run:

    igmp-snooping enable

    IGMP snooping is enabled in the VLAN.

    NOTE:

    Run the igmp-snooping enable [ vlan { vlan-id1 [ to vlan-id2 ] } &<1-10> ] command in the system view to enable IGMP snooping in multiple VLANs.

    IGMP snooping cannot be used with N:1 (N > 1) VLAN mapping.

10.4.2  Configuring the IGMP Snooping Version

Context

IGMP manages multicast group members and runs on the network segments where Layer 3 multicast devices connect to user hosts. IGMP has three protocol versions V1, V2, and V3. You can specify the IGMP snooping version on a Layer 2 device to enable the device to process IGMP messages of the specified version. Generally, the version specified on the Layer 2 device is the same as that configured on the Layer 3 multicast device. If IGMP is disabled on the Layer 3 multicast device, configure the same IGMP version as member hosts or a higher IGMP version.

Devices in the same VLAN must run IGMP of the same version. When hosts that run different IGMP versions exist in a VLAN, configuring IGMP snooping version to enable the device to process IGMP messages of different versions.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping version version

    The version of IGMP messages that the device can process is set.

    By default, the device can process IGMPv1 and IGMPv2 messages but cannot process IGMPv3 messages.

    NOTE:

    When MAC address-based forwarding is enabled in the VLAN, IGMPv3 cannot be configured.

10.4.3  (Optional) Configuring a Static Router Port

Context

A router port is located on a Layer 2 device and connects to an upstream Layer 3 device (a multicast router or Layer 3 switch). When IGMP snooping is enabled in a VLAN, all interfaces in this VLAN learn forwarding entries from multicast protocol packets. When an interface receives IGMP Query messages or Protocol Independent Multicast (PIM) Hello messages, the Layer 2 device sets this interface as a dynamic router port. A router port provides the following functions:

  • Receives multicast data from the upstream device.
  • Forwards IGMP Report/Leave messages. IGMP Report/Leave messages received in a VLAN are forwarded only to router ports in the VLAN.

A dynamic router port has an aging time. If a dynamic router port does not receive an IGMP Query or a PIM Hello message before the aging time expires, the device deletes the port from the router port list. To enable an interface to forward IGMP Report/Leave messages to the upstream querier for a long time, configure the interface as a static router port.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. (Optional) Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. (Optional) Run:

    undo igmp-snooping router-learning

    Dynamic router port learning is disabled.

    By default, dynamic router port learning is enabled in a VLAN.

    NOTE:

    You can also disable router port learning by running the undo igmp-snooping router-learning vlan { { vlan-id1 [ to vlan-id2 ] } &<1–10> | all } command in the interface view.

  4. (Optional) Run:

    quit

    Exit from the VLAN view.

  5. Run:

    interface interface-type interface-number

    The interface view is displayed.

  6. Run:

    igmp-snooping static-router-port vlan { vlan-id1 [ to vlan-id2 ] } &<1-10>

    An interface is configured as a static router port.

10.4.4  (Optional) Configuring a Static Member Port

Context

A member port is on a Layer 2 device and connects to receiver hosts which are multicast group members. The member port can be configured manually or learned dynamically by multicast protocols. When IGMP snooping is enabled in a VLAN, all interfaces in this VLAN learn forwarding entries from multicast packets. When an interface receives IGMP Report messages, the Layer 2 device sets this interface as a dynamic member port. A dynamic member port has the aging time.

If the hosts connected to an interface need to receive the multicast data of a specific multicast group or multicast source group for a long time, add the interface statically to the multicast group or multicast source group. The manually added interface is a static member port. Static member ports do not age.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    interface interface-type interface-number

    The interface view is displayed.

  3. (Optional) Run:

    undo igmp-snooping learning vlan { { vlan-id1 [ to vlan-id2 ] } &<1-10> | all }

    Dynamic learning of member ports is disabled.

    By default, dynamic learning of member ports is enabled. To forward multicast data, the interfaces must be statically added to a multicast group after disabling dynamic learning of member ports.

  4. Run:

    l2-multicast static-group [ source-address source-ip-address ] group-address group-ip-address vlan { vlan-id1 [ to vlan-id2 ] } &<1-10>

    The interface is manually added to a multicast group and becomes a static member port.

    Or run:

    l2-multicast static-group [ source-address source-ip-address ] group-address group-ip-address1 to group-ip-address2 vlan vlan-id

    The interface is added to multiple multicast groups.

10.4.5  (Optional) Configuring an IGMP Snooping Querier

Context

When IGMP snooping is enabled on a Layer 2 device, the Layer 2 device can listen on IGMP protocol packets exchanged between an IGMP querier and user hosts to dynamically create Layer 2 multicast forwarding entries and provide Layer 2 multicast functions.

A Layer 2 device cannot create Layer 2 multicast forwarding entries by listening on IGMP protocol packets in the following conditions, even when IGMP snooping is enabled on the device:

  • The interfaces on the upstream Layer 3 multicast device have static multicast groups configured and do not run the IGMP protocol.

  • The multicast source is located on the same Layer 2 network as user hosts, and therefore no Layer 3 multicast device is required.

In either of the preceding conditions, you can configure the IGMP snooping querier on the Layer 2 multicast device. Then the Layer 2 multicast device substitutes for a Layer 3 multicast device to send IGMP Query messages to user hosts.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping querier enable

    The IGMP snooping querier function is enabled.

    NOTE:
    • The IGMP snooping querier function cannot be enabled in a VLAN if the corresponding Layer 3 VLANIF interface has IGMP enabled.

    • After an IGMP snooping querier is enabled, the switch periodically broadcasts IGMP Query messages to all the interfaces in a VLAN, including the router ports in the VLAN. This may result in IGMP querier reelection if an IGMP querier already exists on the multicast network. If an IGMP querier already exists on the multicast network, configuring IGMP snooping querier is not recommended. If IGMP snooping querier needs to be configured in this condition, ensure that the switch has a larger IP address than the upstream IGMP querier.

    • IGMP snooping querier and IGMP snooping proxy cannot be enabled in the same VLAN.

    • If multicast VLAN replication is configured on the switch, the IGMP snooping querier function cannot be enabled in user VLANs.

  4. (Optional) Set the querier parameters.

    NOTE:

    When setting the querier parameters, ensure that the interval for sending IGMP General Query messages is larger than the maximum response time for IGMP Query messages.

    Querier Parameter

    Configuration Command

    Description

    Default Setting

    Version

    Interval for sending IGMP General Query messages

    igmp-snooping query-interval query-interval

    The querier sends IGMP General Query messages at the specified interval to maintain memberships of interfaces in a VLAN.

    60 seconds

    IGMPv1, IGMPv2, and IGMPv3

    IGMP robustness variable

    igmp-snooping robust-count robust-count

    The robustness variable defines the following values:
    • Number of times the querier sends General Query messages after startup. The packet sending interval is 1/4 of the configured interval for sending General Query messages.
    • Number of times the querier sends Group-Specific Query messages after receiving a Leave message. The packet sending interval is the same as the configured interval for sending Group-Specific Query messages.

    2

    IGMPv1, IGMPv2, and IGMPv3

    Maximum response time for IGMP Query messages

    igmp-snooping max-response-time max-response-time

    When receiving IGMP Report messages from hosts, the switch sets the aging time of member ports by using the following formula: Aging time = IGMP robustness variable x Interval for sending IGMP General Query messages + Maximum response time.

    After a multicast member receives an IGMP Query message, it must send a Report message within the maximum response time.

    10 seconds

    IGMPv2 and IGMPv3

    Interval for sending IGMP Group-Specific Query messages

    igmp-snooping lastmember-queryinterval lastmember-queryinterval

    When receiving IGMP Leave messages from a host, the switch calculates the aging time of the member port by using the following formula: Aging time = Interval for sending Group-Specific Query messages x IGMP robustness variable. The switch sends a Group-Specific Query message certain times (specified by the IGMP robustness variable) to check whether this group has any other members.

    1 second

    IGMPv2 and IGMPv3

  5. (Optional) Run:

    quit

    Return to the system view.

  6. (Optional) Run:

    igmp-snooping send-query source-address ip-address

    The source IP address of an IGMP Query message is configured.

    By default, the source IP address of an IGMP Query message sent by the IGMP snooping querier is 192.168.0.1. If this IP address is used by other devices on the network, you can use this command to set another IP address.

10.4.6  (Optional) Suppressing Report and Leave Messages

Context

IGMP periodically sends Query and Response messages to maintain memberships. When multiple multicast members join the same multicast group, they send a large number of the same Report message to the IGMP router. When IGMPv2 or IGMPv3 hosts leave a multicast group, they send a large number of the same Leave message. To conserve bandwidth, configure suppression for Report and Leave messages on the Layer 2 device.

After message suppression is configured, the switch forwards a Report message only when the first member joins a multicast group or when it receives an IGMP Query message. and a Leave message only when the last member leaves the multicast group.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping report-suppress

    The Report and Leave messages are suppressed.

    NOTE:

    When configuring message suppression, pay attention to the following points:

    • After message suppression is configured in a VLAN, IGMP cannot be enabled on the corresponding VLANIF interface.
    • IGMP snooping proxy and message suppression cannot be configured in the same VLAN.
    • If multicast VLAN replication is configured on the switch, the IGMP message suppression function cannot be enabled in user VLANs.
    • The device can suppress duplicate IGMPv1 or IGMPv2 Report messages even when IGMP message suppression is disabled. The default suppression time is 10 seconds. To change the suppression time, run the igmp-snooping suppress-time suppress-time command. If the suppress-time is set to 0, all the membership packets are forwarded immediately.

10.4.7  (Optional) Configuring the Router-Alert Option

Context

By default, the switch does not check whether IGMP messages contain the Router-Alert option and sends all the IGMP messages to the upper-layer routing protocol. To improve device performance, reduce transmission cost, and enhance protocol security, configure the switch to discard IGMP messages without the Router-Alert option.

By default, the switch sends IGMP messages with the Router-Alert option.

For details about the Router-Alert option, see RFC 2113.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping require-router-alert

    The device is configured to check whether IGMP messages contain the Router-Alert option.

  4. Run:

    igmp-snooping send-router-alert

    The device is configured to send only IGMP messages with the Router-Alert option.

10.4.8  (Optional) Disabling Users from Dynamically Joining Multicast Groups

Context

If an upstream multicast group is a non-Huawei device and has static multicast groups configured on the interface connected to user hosts, multicast users are not allowed to dynamically join or leave the multicast groups. In this case, disable the device from sending IGMP Report and Leave messages that contain static group addresses to the upstream device.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping static-group suppress-dynamic-join

    The switch is disabled from sending IGMP Report and Leave messages that contain static group addresses to the upstream device.

    By default, the device forwards IGMP Report and Leave messages that contain static group addresses to the router port.

10.4.9  Checking the Configuration

Context

After the configurations are complete, run the following commands in any view to check IGMP spooning configurations and the forwarding entries.

Procedure

  • Run the display igmp-snooping [ vlan [ vlan-id ] ] configuration command to check the IGMP snooping configuration in a VLAN.
  • Run the display igmp-snooping [ vlan [ vlan-id ] ] command to check all the IGMP snooping running parameters in a VLAN.
  • Run the display igmp-snooping port-info [ vlan vlan-id [ group-address group-address ] ] [ verbose ] command to check member ports of the multicast group.
  • Run the display igmp-snooping router-port vlan vlan-id command to check router ports.
  • Run the display l2-multicast forwarding-table vlan vlan-id [ [ source-address source-address ] group-address { group-address | router-group } ] command to check the multicast forwarding table in a VLAN.
  • Run the display l2-multicast forwarding-mode vlan [ vlan-id ] command to check multicast data forwarding mode in the VLAN.
  • Run the display igmp-snooping querier vlan [ vlan-id ] command to check the IGMP snooping querier configuration.

10.5  Configuring IGMP Snooping Proxy

IGMP snooping proxy enables the switch to substitute for the Layer 3 device to send IGMP Query messages to user hosts, and substitute for user hosts to send IGMP Report/Leave messages to the Layer 3 device. This function saves bandwidth between the upstream device and local switch.

Pre-configuration Tasks

10.4.1 Enabling IGMP Snooping

Context

When IGMP is disabled on the Layer 3 device (for example, only static multicast group is configured), there is no IGMP querier on the network to maintain multicast memberships. Configure the IGMP snooping proxy function on a Layer 2 device, then the Layer 2 device functions as an IGMP querier to send IGMP Query messages.

When IGMP is enabled on the network, the IGMP snooping proxy function can be deployed on a Layer 2 device to allow the device to substitute for the user host to send IGMP Report messages to the upstream device. In this case, the Layer 3 device receives fewer IGMP Report and Leave messages.

The device configured with IGMP snooping proxy functions as a host for its upstream device and a querier for its downstream device.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping proxy

    IGMP snooping proxy is enabled.

    NOTE:
    • IGMP snooping proxy cannot be enabled in a VLAN if the corresponding VLANIF interface has IGMP enabled.

    • The IGMP snooping querier and IGMP message suppression functions can be enabled in the same VLAN to implement the IGMP snooping proxy function. After you configure the IGMP snooping proxy function in a VLAN, do not configure the IGMP snooping querier or IGMP message suppression function in the VLAN. For detailed configurations of IGMP snooping querier and IGMP message suppression, see 10.4.5 (Optional) Configuring an IGMP Snooping Querier and 10.4.6 (Optional) Suppressing Report and Leave Messages.

    • If multicast VLAN replication is configured on the switch, the IGMP snooping proxy function cannot be enabled in user VLANs.

  4. (Optional) Run:

    quit

    Return to the system view.

  5. (Optional) Run:

    interface interface-type interface-number

    The interface view is displayed.

  6. (Optional) Run:

    igmp-snooping proxy-uplink-port vlan vlan-id

    The switch is disabled from sending IGMP Query messages to the router port.

    After IGMP snooping proxy is enabled in a VLAN, the switch broadcasts IGMP Query messages to all interfaces in the VLAN periodically, including the router port in the VLAN. This may result in reelection of the IGMP querier. To prevent IGMP querier reelection, run this command to disable the switch from sending IGMP Query messages to the router port.

Checking the Configuration

After completing IGMP snooping proxy configuration, you can run the display igmp-snooping [ vlan [ vlan-id ] ] configuration command in any view to check the IGMP snooping proxy configuration in the VLAN.

10.6  Configuring the IGMP Snooping Policy

The IGMP snooping policy controls the multicast programs for users, making the multicast network controllable and secure.

Configuration Process

You can perform the following configuration tasks in any sequence as required.

10.6.1  Configuring a Multicast Group Policy

Context

A multicast group policy determines which multicast groups the hosts in a VLAN can join. The multicast group policy is applicable only to dynamic multicast groups. Before configuring the multicast group policy, create an ACL and define rules. For details about ACL configuration, see "ACL Configuration" in the S7700&S9700 Smart&Core Routing Switch Configuration Guide - Security.

NOTE:

If an advanced ACL is referenced in an IGMP snooping policy, the rules in the ACL can only specify source or destination IP addresses. If the advanced ACL contains a rule that specifies a protocol type or protocol port number, the IGMP snooping policy does not take effect.

When configuring an ACL to be referenced by a multicast group policy in a VLAN, pay attention to the following points:
  • If the default-permit keyword is not specified in the multicast group policy configuration command, specify the permit keyword in the rule command to allow hosts in the VLAN to join the specified groups.
  • If the default-permit keyword is specified in the multicast group policy configuration command, specify the deny keyword in the rule command to prevent hosts in the VLAN from joining the specified groups.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping group-policy acl-number [ version version-number ] [ default-permit ]

    A multicast group policy is configured.

    By default, the user hosts in a VLAN can join any multicast group. If the IGMP version is not specified for a multicast group policy, the switch applies the policy to all the received IGMP messages regardless of their versions.

10.6.2  Filtering Multicast Data on an Interface

Context

To reject certain types of multicast data, a network administrator can configure the switch to filter multicast data packets from a certain VLAN on an interface.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    interface interface-type interface-number

    The interface view is displayed.

  3. Run:

    multicast-source-deny vlan { vlan-id1 [ to vlan-id2 ] } &<1-10>

    The multicast data from a certain VLAN is filtered.

    NOTE:

    You must specify a VLAN to which the interface has already been added. Otherwise, the configuration does not take effect.

    This command can discard only multicast data packets that meet both of the following conditions:
    • The destination MAC address is an IP multicast MAC address (IPv4 MAC address starting with 0x01005E or IPv6 multicast MAC address starting with 0x3333).
    • The packet encapsulation protocol is UDP.

10.6.3  Discarding of Unknown Multicast Flows

Context

Unknown multicast flows are those that do not match any entry in the multicast forwarding table of a switch. These flows are not requested by users, and may be sent from the upstream device for certain purpose, for example, to improve the multicast service speed. Unknown multicast flows should be terminated on the switch and should not be broadcast in a VLAN.

When Layer 2 multicast is not enabled on the switch, the switch broadcasts unknown multicast flows in a VLAN. If users do not need to receive multicast flows, you can configure the switch to drop unknown multicast flows using the multicast drop-unknown command. This configuration reduces instant bandwidth usage.

After Layer 2 multicast is enabled:
  • If the IP address-based Layer 2 multicast forwarding mode is used, unknown multicast flows are not broadcast in a VLAN. In this case, the switches do not drop unknown multicast flows, regardless of whether the multicast drop-unknown command is configured.
  • If the MAC address-based Layer 2 multicast forwarding mode is used, the switches broadcast unknown multicast flows in a VLAN. After you run the multicast drop-unknown command, the switches drop unknown multicast flows received from upstream devices.

You can run the l2-multicast forwarding-mode { ip | mac } command in the VLAN view to configure the Layer 2 multicast forwarding mode. By default, multicast data is forwarded in a VLAN based on IP addresses.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    multicast drop-unknown

    The switch is configured to discard unknown multicast flows.

    NOTE:

    Some protocol packets, such as OSPF packets, VRRP packets, and IPv6 RA messages, use reserved group addresses as destination MAC and IP addresses and match no multicast forwarding entry. If the switch is configured to drop unknown multicast packets using the multicast drop-unknown command, the switch drops these protocol packets. Therefore, do not use this command in a VLAN if the switch needs to transparently transmit protocol packets with reserved group addresses.

    After the multicast drop-unknown command is run, the switch discards all unknown IPv4 and IPv6 multicast packets, including the protocol packets that are transparently transmitted within the VLAN and use the reserved multicast address.

10.6.4  Checking the Configuration

Prerequisites

After the configurations of IGMP snooping policy are complete, run the following commands in any view to check the policy configurations and usage.

Procedure

  • Run the display igmp-snooping [ vlan [ vlan-id ] ] configuration command to check the IGMP snooping configuration.

    The configurations of IGMP snooping include the configurations of IGMP snooping policy in the VLAN.

  • Run the display l2-multicast forwarding-table vlan vlan-id [ [ source-address source-address ] group-address { group-address | router-group } ] command to check the multicast forwarding table in a VLAN.

    You can check whether a Layer 2 multicast policy is used correctly by viewing Layer 2 multicast forwarding entries.

10.7  Configuring Membership Fast-Update

The switch is configured to rapidly update memberships when a multicast group member joins or leaves the multicast group. This improves the efficiency and user experience of multicast services.

Configuration Process

You can perform the following configuration tasks in any sequence as required.

10.7.1  Setting the Aging Time of Group Member Ports

Context

A device sets the aging time of a group member port depending on the IGMP message received on the member port:
  • When the member port receives a Report message from a downstream host, the device sets the aging time to: Robustness variable x General Query interval + Maximum response time for General Query messages.

  • When the member port receives a Leave message from a downstream host, the device sets the aging time to: Last member query interval x Robustness variable.

When deploying a Layer 2 multicast network, ensure that all the Layer 2 multicast devices use the same parameter values to calculate the aging time of dynamic group member ports, especially the IGMP snooping general query interval. Otherwise, errors may occur in Layer 2 multicast forwarding.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping query-interval query-interval

    The IGMP snooping general query interval is configured.

    By default, the IGMP snooping general query interval is 60 seconds.

    NOTE:

    The default general query interval defined in RFC documents is 125 seconds, but some vendors define their own default general query intervals. It is recommended that all devices on a multicast network use the same general query intervals (including IGMP and IGMP snooping genreal query intervals).

    Table 10-2 lists the default general query interval values on Huawei S series switches.
    Table 10-2  Default general query interval values
    Feature Default Value on Modular Switches Default Value on Fixed Switches
    IGMP 60s 60s
    IGMP snooping 60s 125s

  4. Run:

    igmp-snooping robust-count robust-count

    The IGMP snooping robustness variable is configured.

    By default, the IGMP snooping robustness variable is 2.

  5. Run:

    igmp-snooping max-response-time max-response-time

    The IGMP snooping maximum response time is set.

    By default, the IGMP snooping maximum response time is 10 seconds.

  6. Run:

    igmp-snooping lastmember-queryinterval lastmember-queryinterval

    The IGMP snooping last member query interval is configured.

    By default, the IGMP snooping last member query interval is 1 second.

10.7.2  Setting the Aging Time of Dynamic Router Ports

Context

A router port sends IGMP Report/leave messages to an upstream Layer 3 device and receives multicast packets from the upstream device. When IGMP snooping is enabled on a device, the device can learn entries of the dynamic router port to monitor the sending of multicast data. When network congestion or flapping occurs, the dynamic router port does not receive General IGMP Query or PIM Hello messages before it times out. The switch deletes the interface from the router port list, which may cause service interruption. To avoid this problem, set a longer aging time.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping router-aging-time router-aging-time

    The aging time is set for dynamic router ports.

    By default, the aging time of router ports that the switch learns from General IGMP Query messages is 180 seconds. By default, the aging time of router ports that the switch learns from PIM Hello messages is the Holdtime value in PIM Hello messages.

10.7.3  Configuring Fast Leave for Member Ports

Context

When the switch receives IGMP Leave messages from a member interface, the fast leave function allows the switch immediately deletes forwarding entries of the member interface but not reset the aging timer.

NOTE:
  • Enable fast leave for member ports in the VLAN only when each interface in a VLAN is connected to one receiver host.

  • Prompt leave takes effect for member ports in a VLAN only when the switch can process IGMPv2 messages.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping prompt-leave [ group-policy acl-number [ default-permit ] ]

    Prompt leave is configured on the member port.

    By default, no member port is allowed to fast leave a multicast group.

    If you do not specify group-policy when configuring the fast leave function, this function takes effect for all groups. To specify a group policy in the command, create an ACL and configure rules for the ACL before running the command. The ACL rules filter groups in different ways depending on whether default-permit is specified in the command:
    • If default-permit is not specified in the command, the group policy prevents member ports in the VLAN from fast leaving any group by default. Specify the permit keyword in the rule command to allow member ports in the VLAN to fast leave the specified groups.
    • If default-permit is specified in the command, the group policy allows member ports in the VLAN to fast leave all groups by default. Specify the deny keyword in the rule command to prevent member ports in the VLAN from fast leaving the specified groups.
    For details on how to configure an ACL, see "ACL Configuration" in the S7700&S9700 Smart&Core Routing Switch Configuration Guide - Security.

10.7.4  Sending IGMP Query Messages upon Topology Changes

Context

When a Layer 2 network topology changes, the forwarding path of multicast packets may change. When a fault occurs on a link, the switch sends IGMP Query messages and the multicast members reply with IGMP Report messages. The switch then updates information about multicast member ports based on the IGMP Report messages. In this manner, multicast packets can be quickly switched to new forwarding paths.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    igmp-snooping send-query enable

    IGMP Query messages are sent upon topology changes.

    By default, the switch is disabled from sending IGMP Query messages upon topology changes.

    This command enables the switch to send IGMP Query messages (the source IP address is 192.168.0.1 by default) upon topology changes, and quickly update information about multicast member ports, so that multicast packets to the downstream members are interrupted only for a short period.

  3. (Optional) Run:

    igmp-snooping send-query source-address ip-address

    The source IP address of an IGMP Query message is configured.

    By default, the source IP address of an IGMP Query message sent upon topology changes is 192.168.0.1. If this IP address is used by other devices on the network, you can use this command to set another IP address.

10.7.5  Deleting IGMP Snooping Entries of DHCP Snooping Users Immediately After the Users Go Offline

Context

When IGMP snooping and DHCP snooping are enabled for users, the switch does not delete the IGMP snooping entry of a user immediately after the user goes offline. The multicast flow requested by the user is still transmitted until the IGMP snooping entry of the user ages.

You can configure the switch to delete the IGMP snooping entry of a DHCP snooping user immediately after the user goes offline so that the multicast flow requested by the user is immediately terminated.

For detailed information, see the chapter "DHCP Snooping Configuration" in the Configuration Guide - Security.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    dhcp-snooping user-offline remove igmp-snooping

    The switch is configured to delete IGMP snooping entries of DHCP snooping users immediately after the users go offline.

10.7.6  Checking the Configuration

Prerequisites

After the configuration of membership fast-update is complete, you can run the following commands in any view to check the IGMP snooping configuration and forwarding entries.

Procedure

  • Run the display igmp-snooping [ vlan [ vlan-id ] ] configuration command to check the IGMP snooping configuration.
  • Run the display l2-multicast forwarding-table vlan vlan-id [ [ source-address source-address ] group-address { group-address | router-group } ] command to check the multicast forwarding table in a VLAN.

10.8  Configuring IGMP Snooping SSM Mapping

If user hosts on a Layer 2 network run only IGMPv1 or IGMPv2, enable SSM mapping on the switch to provide SSM services for these hosts.

Pre-configuration Tasks

10.4.1 Enabling IGMP Snooping

10.8.1  (Optional) Configuring an SSM Group Policy

Context

By default, the address of an SSM group ranges from 232.0.0.0 to 232.255.255.255. If a user joins a multicast group whose IP address is not in this range, configure an SSM group policy in the VLAN to add the multicast group address to the range of SSM group addresses. The SSM group policy must be used together with an ACL. For details on how to configure an ACL, see "ACL Configuration" in the S7700&S9700 Smart&Core Routing Switch Configuration Guide - Security.

NOTE:

By default, the ACL applied to an SSM group policy denies all multicast groups. Therefore, to exclude specific group addresses from the SSM group address range, use a rule permit source any rule with deny rules in the ACL.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping ssm-policy basic-acl-number

    An SSM group policy is configured.

    After you configure an SSM group policy, the multicast groups specified in the SSM policy are considered as SSM groups.

10.8.2  Configuring IGMP Snooping SSM Mapping

Context

  • By configuring SSM mapping, you can set up one-to-one mappings between multicast groups and multicast sources.

  • SSM mapping applies only to the scenario where IGMP snooping in the VLAN can process IGMPv3 messages.

  • If the inter-VLAN multicast replication function is configured, you only need to configure SSM mapping in the multicast VLAN.

  • Although SSM mapping takes effect only for IGMPv3 messages in a VLAN, the switch does not convert IGMPv2 messages into IGMPv3 messages before sending the messages to router ports. You can configure IGMP snooping proxy or IGMP snooping Report suppression on the switch to enable the switch to send IGMPv3 messages to the upstream device.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    vlan vlan-id

    The VLAN view is displayed.

  3. Run:

    igmp-snooping version  3

    The version of IGMP snooping run in the VLAN is set to 3.

    The default version number of IGMP snooping is 2, but IGMPv2 version does not support SSM mapping.

  4. Run:

    igmp-snooping ssm-mapping enable

    SSM mapping is enabled in the VLAN.

    By default, SSM mapping is disabled in a VLAN.

  5. Run:

    igmp-snooping ssm-mapping group-address { group-mask | mask-length } source-address

    The mapping between a group address and a multicast source address is configured.

    The group address must be in the SSM group address range. If you want to change the SSM group address range, see 10.8.1 (Optional) Configuring an SSM Group Policy.

10.8.3  Checking the Configuration

Context

After configuring SSM mapping, run the following command in any view to check the configured SSM mapping entries.

Procedure

  • Run the display igmp-snooping port-info [ vlan vlan-id [ group-address group-address ] ] [ verbose ] command to check information about IGMP snooping interfaces.

10.9  Maintaining IGMP Snooping

You can maintain the IGMP snooping feature by clearing IGMP snooping entries, clearing IGMP snooping statistics, and monitoring IGMP snooping running status.

10.9.1  Clearing IGMP Snooping Entries

Context

IGMP snooping entries are classified into static and dynamic entries, and they are cleared in different ways.

NOTICE:

Static entries cannot be restored after being cleared and can be created when you configure static member ports.

When dynamic entries in a forwarding table are cleared, the hosts in the VLAN do not receive the multicast packets temporarily. The hosts in the VLAN receive the multicast packets again only after the hosts send IGMP Report messages and the forwarding entries are regenerated on the switch.

Procedure

  • Run the undo l2-multicast static-group [ source-address source-ip-address ] group-address group-ip-address vlan { all | { vlan-id1 [ to vlan-id2 ] } &<1-10> } command in the interface view to remove the interface from a multicast group.

    You can run the following commands to batch remove the multicast group addresses that the interface joins.

    • undo l2-multicast static-group [ source-address source-ip-address ] group-address group-ip-address1 to group-ip-address2 vlan vlan-id
    • undo l2-multicast static-group [ source-address source-ip-address ] group-address all vlan { all | { vlan-id1 [ to vlan-id2 ] } &<1-10> }

  • Run the reset igmp-snooping group { all | vlan { all | vlan-id [ [ source-address source-address ] group-address group-address ] } } command in the user view to remove dynamic entries in a forwarding table.

10.9.2  Clearing IGMP Snooping Statistics

Context

IGMP snooping statistics include the number of IGMP Report, Leave, and Query messages received in a VLAN. To collect IGMP snooping statistics in a period of time, run the reset command to set the IGMP snooping statistics to 0.

NOTICE:

IGMP snooping statistics cannot be restored after being cleared. Exercise caution when you use the command.

Procedure

  • Run the reset igmp-snooping statistics { all | vlan { vlan-id | all } } command in the user view to clear IGMP snooping statistics.

10.9.3  Displaying the IGMP Snooping Running Status

Context

To check the IGMP snooping running status during routine maintenance, run the following display commands in any view.

Procedure

  • Run the display igmp-snooping [ vlan [ vlan-id ] ] command to check all the IGMP snooping running parameters in a VLAN.
  • Run the display igmp-snooping [ vlan [ vlan-id ] ] configuration command to check the IGMP snooping configuration in a VLAN.
  • Run the display igmp-snooping port-info [ vlan vlan-id [ group-address group-address ] ] [ verbose ] command to check information about member ports.
  • Run the display igmp-snooping router-port vlan vlan-id command to check information about router ports.
  • Run the display igmp-snooping querier vlan [ vlan-id ] command to check information about the IGMP snooping querier.
  • Run the display igmp-snooping statistics vlan [ vlan-id ] command to check IGMP snooping statistics.
  • Run the display l2-multicast forwarding-mode vlan [ vlan-id ] command to check the multicast forwarding mode.
  • Run the display l2-multicast forwarding-table vlan vlan-id [ [ source-address source-address ] group-address { group-address | router-group } ] command to check the multicast forwarding table in a VLAN.

10.10  Configuration Examples

This section provides IGMP snooping configuration examples to help you configure basic IGMP snooping functions, static interfaces, an IGMP snooping querier, an IGMP snooping proxy, and Layer 2 multicast SSM mapping.

10.10.1  Example for Configuring IGMP Snooping

Networking Requirements

As shown in Figure 10-2, Router connects to user hosts through a Layer 2 Switch and Router runs IGMPv2. The multicast source sends data to multicast groups 225.1.1.1 to 225.1.1.5. On the network, there are three receivers HostA, HostB, and HostC and the three hosts only want to receive data of multicast groups 225.1.1.1 to 225.1.1.3.

Figure 10-2  Networking diagram for IGMP snooping configuration

Configuration Roadmap

To meet the preceding requirements, configure basic IGMP snooping functions and a multicast group policy on the Layer 2 Switch. The configuration roadmap is as follows:

  1. On the Switch, create a VLAN and add interfaces to the VLAN.
  2. Enable IGMP snooping globally and in the VLAN.
  3. Configure a multicast group policy and apply this policy to the VLAN.

Procedure

  1. Create a VLAN and add interfaces to the VLAN.

    <Quidway> system-view
    [Quidway] sysname Switch
    [Switch] vlan 10
    [Switch-vlan10] quit
    [Switch] interface gigabitethernet 1/0/1
    [Switch-GigabitEthernet1/0/1] port hybrid pvid vlan 10
    [Switch-GigabitEthernet1/0/1] port hybrid untagged vlan 10
    [Switch-GigabitEthernet1/0/1] quit
    [Switch] interface gigabitethernet 2/0/2
    [Switch-GigabitEthernet2/0/2] port hybrid pvid vlan 10
    [Switch-GigabitEthernet2/0/2] port hybrid untagged vlan 10
    [Switch-GigabitEthernet2/0/2] quit
    [Switch] interface gigabitethernet 3/0/3
    [Switch-GigabitEthernet3/0/3] port hybrid pvid vlan 10
    [Switch-GigabitEthernet3/0/3] port hybrid untagged vlan 10
    [Switch-GigabitEthernet3/0/3] quit

  2. Enable IGMP snooping.

    # Enable IGMP snooping globally.

    [Switch] igmp-snooping enable

    # Enable IGMP snooping in VLAN 10.

    [Switch] vlan 10
    [Switch-vlan10] igmp-snooping enable
    [Switch-vlan10] quit
    NOTE:

    After the configuration is complete, the switch can generate Layer 2 multicast forwarding entries by listening on IGMP messages. Ensure that the general query interval configured on the switch is the same as that on the upstream Layer 3 multicast device (router). Otherwise, some Layer 2 multicast forwarding entries may be aged out incorrectly, causing multicast traffic interruption. If the default general query interval of the switch is different from that of the router, run the igmp-snooping query-interval query-interval command in VLAN 10 to change the general query interval on the switch.

  3. Configure a multicast group policy and apply this policy.

    # Configure a multicast group policy.

    [Switch] acl 2000
    [Switch-acl-basic-2000] rule permit source 225.1.1.1 0
    [Switch-acl-basic-2000] rule permit source 225.1.1.2 0
    [Switch-acl-basic-2000] rule permit source 225.1.1.3 0
    [Switch-acl-basic-2000] quit

    # Apply the multicast group policy in VLAN 10.

    [Switch] vlan 10
    [Switch-vlan10] igmp-snooping group-policy 2000
    [Switch-vlan10] quit

  4. Verify the configuration.

    # Check the interface information on the Switch.

    <Switch> display igmp-snooping port-info vlan 10 
     -----------------------------------------------------------------------
                         (Source, Group)  Port                          Flag
      Flag: S:Static     D:Dynamic     M: Ssm-mapping                       
     -----------------------------------------------------------------------
     VLAN 10, 3 Entry(s)                                                    
                          (*, 225.1.1.1)  GE1/0/1                        -D-
                                          GE2/0/2                        -D-
                                                    2 port(s)
                          (*, 225.1.1.2)  GE1/0/1                        -D-
                                          GE2/0/2                        -D-
                                                    2 port(s)
                          (*, 225.1.1.3)  GE1/0/1                        -D-
                                          GE2/0/2                        -D-
                                                    2 port(s)
     -----------------------------------------------------------------------

    The command output shows that multicast groups 225.1.1.1 to 225.1.1.3 have dynamically generated member ports GE1/0/1 and GE2/0/2 on the Switch.

    # Check the Layer 2 multicast forwarding table on the Switch.

    <Switch> display l2-multicast forwarding-table vlan 10
    VLAN ID : 10, Forwarding Mode : IP                                     
    ------------------------------------------------------------------------
                         (Source, Group)    Interface               Out-Vlan
    ------------------------------------------------------------------------
                             Router-port    GigabitEthernet3/0/3       10
                          (*, 225.1.1.1)    GigabitEthernet1/0/1       10
                                            GigabitEthernet2/0/2       10
                                            GigabitEthernet3/0/3       10
                          (*, 225.1.1.2)    GigabitEthernet1/0/1       10
                                            GigabitEthernet2/0/2       10
                                            GigabitEthernet3/0/3       10
                          (*, 225.1.1.3)    GigabitEthernet1/0/1       10
                                            GigabitEthernet2/0/2       10
                                            GigabitEthernet3/0/3       10
    ----------------------------------------------------------------------
    Total Group(s) : 3

    The command output shows that the forwarding table contains only information about multicast groups 225.1.1.1 to 225.1.1.3. The multicast groups 225.1.1.4 to 225.1.1.5 do not forward data to the hosts.

Configuration Files

  • Configuration file of the Switch

    #
    sysname Switch
    #
    vlan batch 10
    #
    igmp-snooping enable
    #
    acl number 2000
     rule 5 permit source 225.1.1.1 0
     rule 10 permit source 225.1.1.2 0
     rule 15 permit source 225.1.1.3 0
    #
    vlan 10
     igmp-snooping enable
     igmp-snooping group-policy 2000
    #
    interface GigabitEthernet1/0/1
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet2/0/2
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet3/0/3
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    return

10.10.2  Example for Configuring Layer 2 Multicast Through Static Interfaces

Networking Requirements

As shown in Figure 10-3, Router connects to user hosts through a Layer 2 swtich. The user-side VLANIF interface of Router has static groups 225.1.1.1 to 225.1.1.5 configured and does not run IGMP. There are four receivers on the network: HostA, HostB, HostC, and HostD. HostA and HostB expect to receive data of multicast groups 225.1.1.1 to 225.1.1.3 for long time. HostC and HostD expect to receive data of multicast groups 225.1.1.4 to 225.1.1.5.

Figure 10-3  Networking diagram for Layer 2 multicast configuration through static interfaces

Configuration Roadmap

To meet the preceding requirements, configure a static router port and static member ports of IGMP snooping on the Layer 2 Switch. The configuration roadmap is as follows:

  1. On the Switch, create a VLAN and add interfaces to the VLAN.
  2. Enable IGMP snooping globally and in the VLAN.
  3. Configure a static router port.
  4. Configure static member ports.

Procedure

  1. Create a VLAN and add interfaces to the VLAN.

    <Quidway> system-view
    [Quidway] sysname Switch
    [Switch] vlan 10
    [Switch-vlan10] quit
    [Switch] interface gigabitethernet 1/0/1
    [Switch-GigabitEthernet1/0/1] port hybrid pvid vlan 10
    [Switch-GigabitEthernet1/0/1] port hybrid untagged vlan 10
    [Switch-GigabitEthernet1/0/1] quit
    [Switch] interface gigabitethernet 2/0/2
    [Switch-GigabitEthernet2/0/2] port hybrid pvid vlan 10
    [Switch-GigabitEthernet2/0/2] port hybrid untagged vlan 10
    [Switch-GigabitEthernet2/0/2] quit
    [Switch] interface gigabitethernet 3/0/3
    [Switch-GigabitEthernet3/0/3] port hybrid pvid vlan 10
    [Switch-GigabitEthernet3/0/3] port hybrid untagged vlan 10
    [Switch-GigabitEthernet3/0/3] quit

  2. Enable IGMP snooping.

    # Enable IGMP snooping globally.

    [Switch] igmp-snooping enable

    # Enable IGMP snooping in VLAN 10.

    [Switch] vlan 10
    [Switch-vlan10] igmp-snooping enable
    [Switch-vlan10] quit

  3. Configure a static router port.

    [Switch] interface gigabitethernet 3/0/3
    [Switch-GigabitEthernet3/0/3] igmp-snooping static-router-port vlan 10
    [Switch-GigabitEthernet3/0/3] quit
    

  4. Configure static member ports.

    [Switch] interface gigabitethernet 1/0/1
    [Switch-GigabitEthernet1/0/1] l2-multicast static-group group-address 225.1.1.1 to 225.1.1.3 vlan 10
    [Switch-GigabitEthernet1/0/1] quit
    [Switch] interface gigabitethernet 2/0/2
    [Switch-GigabitEthernet2/0/2] l2-multicast static-group group-address 225.1.1.4 to 225.1.1.5 vlan 10
    [Switch-GigabitEthernet2/0/2] quit
    

  5. Verify the configuration.

    # Check the router port information on the Switch.

    <Switch> display igmp-snooping router-port vlan 10 
     Port Name                       UpTime        Expires       Flags
     ---------------------------------------------------------------------
     VLAN 10, 1 router-port(s)
     GE3/0/3                         00:20:09      --            STATIC

    The command output shows that GE3/0/3 has been configured as static router port.

    # Check the member port information on the Switch.

    <Switch> display igmp-snooping port-info vlan 10
     -----------------------------------------------------------------------
                         (Source, Group)  Port                          Flag
      Flag: S:Static     D:Dynamic     M: Ssm-mapping                       
     -----------------------------------------------------------------------
     VLAN 10, 5 Entry(s)
                          (*, 225.1.1.1)  GE1/0/1                        S--
                                                    1 port(s)                       
                          (*, 225.1.1.2)  GE1/0/1                        S--
                                                    1 port(s)                       
                          (*, 225.1.1.3)  GE1/0/1                        S--
                                                    1 port(s)                       
                          (*, 225.1.1.4)  GE2/0/2                        S--
                                                    1 port(s)                       
                          (*, 225.1.1.5)  GE2/0/2                        S--
                                                    1 port(s)
     -----------------------------------------------------------------------

    The command output shows that multicast groups 225.1.1.1 to 225.1.1.3 have a static member port GE1/0/1 on the Switch and multicast groups 225.1.1.4 to 225.1.1.5 have a static member port GE2/0/2 on the Switch.

    # Check the Layer 2 multicast forwarding table on the Switch.

    <Switch> display l2-multicast forwarding-table vlan 10
    VLAN ID : 10, Forwarding Mode : IP                                         
    ---------------------------------------------------------------------------
                         (Source, Group)    Interface                  Out-Vlan
    ---------------------------------------------------------------------------
                             Router-port    GigabitEthernet3/0/3          10
                          (*, 225.1.1.1)    GigabitEthernet1/0/1          10
                                            GigabitEthernet3/0/3          10
                          (*, 225.1.1.2)    GigabitEthernet1/0/1          10
                                            GigabitEthernet3/0/3          10
                          (*, 225.1.1.3)    GigabitEthernet1/0/1          10
                                            GigabitEthernet3/0/3          10
                          (*, 225.1.1.4)    GigabitEthernet2/0/2          10
                                            GigabitEthernet3/0/3          10
                          (*, 225.1.1.5)    GigabitEthernet2/0/2          10
                                            GigabitEthernet3/0/3          10
    --------------------------------------------------------------------------
    Total Group(s) : 5

    The command output shows that multicast groups 225.1.1.1 to 225.1.1.5 have a forwarding table on the Switch.

Configuration Files

  • Configuration file of the Switch

    #
    sysname Switch
    #
    vlan batch 10
    #
    igmp-snooping enable
    #
    vlan 10
     igmp-snooping enable
    #
    interface GigabitEthernet1/0/1
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
     l2-multicast static-group group-address 225.1.1.1 to 225.1.1.3 vlan 10 
    #
    interface GigabitEthernet2/0/2
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
     l2-multicast static-group group-address 225.1.1.4 to 225.1.1.5 vlan 10 
    #
    interface GigabitEthernet3/0/3
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
     igmp-snooping static-router-port vlan 10 
    #
    return

10.10.3  Example for Configuring an IGMP Snooping Querier

Networking Requirements

As shown in Figure 10-4, on a pure Layer 2 network, multicast sources Source1 and Source2 send multicast data to multicast groups 224.1.1.1 and 225.1.1.1. HostA and HostC expect to receive data of multicast group 224.1.1.1 for long time, while HostB and HostD expect to receive data of multicast group 225.1.1.1 for long time. All the hosts run IGMPv2.

Figure 10-4  Networking diagram for IGMP snooping querier configuration

Configuration Roadmap

To meet the preceding requirements, enable IGMP snooping on the four switches and configure an IGMP snooping querier. Enable all the switches to discard unknown multicast packets to prevent the switches from broadcasting multicast data in the VLAN when there are no Layer 2 multicast forwarding entries on the switches. The configuration roadmap is as follows:

  1. On all the switches, create a VLAN and add interfaces to the VLAN according to Figure 10-4.
  2. Enable IGMP snooping globally and in the VLAN on all the switches.
  3. Configure SwitchA as an IGMP snooping querier.
  4. Enable all the Switches to discard unknown multicast packets.

Procedure

  1. On all the switches, create a VLAN and add interfaces to the VLAN.

    # Configure SwitchA.

    <Quidway> system-view
    [Quidway] sysname SwitchA
    [SwitchA] vlan 10
    [SwitchA-vlan10] quit
    [SwitchA] interface gigabitethernet 1/0/1
    [SwitchA-GigabitEthernet1/0/1] port hybrid pvid vlan 10
    [SwitchA-GigabitEthernet1/0/1] port hybrid untagged vlan 10
    [SwitchA-GigabitEthernet1/0/1] quit
    [SwitchA] interface gigabitethernet 2/0/2
    [SwitchA-GigabitEthernet2/0/2] port hybrid pvid vlan 10
    [SwitchA-GigabitEthernet2/0/2] port hybrid untagged vlan 10
    [SwitchA-GigabitEthernet2/0/2] quit
    [SwitchA] interface gigabitethernet 3/0/3
    [SwitchA-GigabitEthernet3/0/3] port hybrid pvid vlan 10
    [SwitchA-GigabitEthernet3/0/3] port hybrid untagged vlan 10
    [SwitchA-GigabitEthernet3/0/3] quit

    # The configurations of SwitchB, SwitchC and SwitchD are similar to the configuration of SwitchA, and the configurations are not provided here.

  2. Enable IGMP snooping globally and in the VLAN on all the switches.

    # Configure SwitchA.

    [SwitchA] igmp-snooping enable
    [SwitchA] vlan 10
    [SwitchA-vlan10] igmp-snooping enable
    [SwitchA-vlan10] quit

    # The configurations of SwitchB, SwitchC and SwitchD are similar to the configuration of SwitchA, and the configurations are not provided here.

  3. Configure SwitchA as an IGMP snooping querier.

    [SwitchA] vlan 10
    [SwitchA-vlan10] igmp-snooping querier enable
    [SwitchA-vlan10] quit

  4. Enable all the switches to discard unknown multicast packets.

    # Configure SwitchA.

    [SwitchA] vlan 10
    [SwitchA-vlan10] multicast drop-unknown
    [SwitchA-vlan10] quit
    

    # The configurations of SwitchB, SwitchC and SwitchD are similar to the configuration of SwitchA, and the configurations are not provided here.

  5. Verify the configuration.

    # When the IGMP snooping querier begins to work, all the switches except the IGMP snooping querier receive IGMP General Query messages. Run the display igmp-snooping statistics vlan 10 command on SwitchB to view IGMP message statistics. The command output is as follows:

    <SwitchB> display igmp-snooping statistics vlan 10
     IGMP Snooping Packets Counter
       Statistics for VLAN 10
         Recv V1 Report          0
         Recv V2 Report          32
         Recv V3 Report          0
         Recv V1 Query           0
         Recv V2 Query       30
         Recv V3 Query           0
         Recv Leave              0
         Recv Pim Hello          0
         Send Query(S=0)         0
         Send Query(S!=0)        0
         Suppress Report         0
         Suppress Leave          0
         Proxy Send General Query               0
         Proxy Send Group-Specific Query        0
         Proxy Send Group-Source-Specific Query 0

Configuration Files

  • Configuration file of SwitchA

    #
    sysname SwitchA
    #
    vlan batch 10
    #
    igmp-snooping enable
    #
    vlan 10
     multicast drop-unknown
     igmp-snooping enable
     igmp-snooping querier enable
    #
    interface GigabitEthernet1/0/1
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet2/0/2
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet3/0/3
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    return
  • Configuration file of SwitchB

    #
    sysname SwitchB
    #
    vlan batch 10
    #
    igmp-snooping enable
    #
    vlan 10
     multicast drop-unknown
     igmp-snooping enable
    #
    interface GigabitEthernet1/0/1
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet2/0/2
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet3/0/3
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet4/0/4
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    return
  • Configuration file of SwitchC

    #
    sysname SwitchC
    #
    vlan batch 10
    #
    igmp-snooping enable
    #
    vlan 10
     multicast drop-unknown
     igmp-snooping enable
    #
    interface GigabitEthernet1/0/1
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet2/0/2
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet3/0/3
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    return
  • Configuration file of SwitchD

    #
    sysname SwitchD
    #
    vlan batch 10
    #
    igmp-snooping enable
    #
    vlan 10
     multicast drop-unknown
     igmp-snooping enable
    #
    interface GigabitEthernet1/0/1
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet2/0/2
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    return

10.10.4  Example for Configuring IGMP Snooping Proxy

Networking Requirements

As shown in Figure 10-5, Router connects to user hosts through a Layer 2 Switch and Router runs IGMPv3. There are multiple receiver hosts on the network, and the administrator expects that exchange of IGMP messages will not be a burden to Router.

Figure 10-5  Networking diagram for the IGMP snooping proxy configuration

Configuration Roadmap

To meet the preceding requirements, configure IGMP snooping proxy on the Switch. The configuration roadmap is as follows:

  1. Create a VLAN and add interfaces to the VLAN.

  2. Enable IGMP snooping globally and in the VLAN.

  3. Configure IGMP snooping proxy on the Switch to reduce packet exchange between the Switch and Router.

  4. Disable the Switch from sending IGMP Query messages to the upstream Router to prevent election of the IGMP querier.

Procedure

  1. Create a VLAN and add interfaces to the VLAN.

    <Quidway> system-view
    [Quidway] sysname Switch
    [Switch] vlan 10
    [Switch-vlan10] quit
    [Switch] interface gigabitethernet 1/0/1
    [Switch-GigabitEthernet1/0/1] port hybrid pvid vlan 10
    [Switch-GigabitEthernet1/0/1] port hybrid untagged vlan 10
    [Switch-GigabitEthernet1/0/1] quit
    [Switch] interface gigabitethernet 2/0/2
    [Switch-GigabitEthernet2/0/2] port hybrid pvid vlan 10
    [Switch-GigabitEthernet2/0/2] port hybrid untagged vlan 10
    [Switch-GigabitEthernet2/0/2] quit
    [Switch] interface gigabitethernet 3/0/3
    [Switch-GigabitEthernet3/0/3] port hybrid pvid vlan 10
    [Switch-GigabitEthernet3/0/3] port hybrid untagged vlan 10
    [Switch-GigabitEthernet3/0/3] quit

  2. Enable IGMP snooping.

    # Enable IGMP snooping globally.

    [Switch] igmp-snooping enable

    # Enable IGMP snooping in VLAN 10.

    [Switch] vlan 10
    [Switch-vlan10] igmp-snooping enable
    

    # Configure IGMPv3 snooping to enable the Switch to process IGMP messages of all versions.

    [Switch-vlan10] igmp-snooping version 3
    

  3. Enable IGMP snooping proxy.

    [Switch-vlan10] igmp-snooping proxy
    [Switch-vlan10] quit

  4. Disable the Switch from sending IGMP Query messages to the upstream Router.

    [Switch] interface gigabitethernet 3/0/3
    [Switch-GigabitEthernet3/0/3] igmp-snooping proxy-uplink-port vlan 10
    [Switch-GigabitEthernet3/0/3] quit

  5. Verify the configuration.

    # Check IGMP message statistics on the Switch.

    <Switch> display igmp-snooping statistics vlan 10
     IGMP Snooping Packets Counter
       Statistics for VLAN 10
         Recv V1 Report  0
         Recv V2 Report  121
         Recv V3 Report  0
         Recv V1 Query   0
         Recv V2 Query   0
         Recv V3 Query   0
         Recv Leave      82
         Recv Pim Hello  0
         Send Query(S=0) 0
         Send Query(S!=0)0
         Suppress Report         0
         Suppress Leave          0
         Proxy Send General Query          135
         Proxy Send Group-Specific Query        95
         Proxy Send Group-Source-Specific Query 0

    The command output shows that the IGMP snooping proxy takes effect as the Switch functions as a proxy to send IGMP General Query messages.

Configuration Files

  • Configuration file of the Switch

    #
    sysname Switch
    #
    vlan batch 10
    #
    igmp-snooping enable
    #
    vlan 10
     igmp-snooping enable
     igmp-snooping version 3
     igmp-snooping proxy
    #
    interface GigabitEthernet1/0/1
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet2/0/2
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet3/0/3
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
     igmp-snooping proxy-uplink-port vlan 10 
    #
    return

10.10.5  Example for Configuring IGMP Snooping SSM Mapping

Networking Requirements

As shown in Figure 10-6, Router connects to user hosts through a Layer 2 Switch. Router runs IGMPv3 and uses the ASM mode and SSM mode to provide multicast services. User hosts HostA, HostB, and HostC on the network run IGMPv2 and do not support IGMPv3. The multicast sources Source1 and Source2 send multicast data to the multicast group 225.1.1.1, but the user hosts want to receive only the multicast data sent from Source1.

Figure 10-6  Networking diagram for the SSM mapping configuration

Configuration Roadmap

To meet the preceding requirements, configure SSM mapping on the Switch. The configuration roadmap is as follows:

  1. On the Switch, create a VLAN and add interfaces to the VLAN.

  2. Enable IGMP snooping globally and in the VLAN.

  3. Configure an IGMP snooping SSM policy to add the multicast address of the ASM mode to the SSM group address range.

  4. Configure SSM mapping to allow the users to receive only multicast data sent from the specified source.

Procedure

  1. Create a VLAN and add interfaces to the VLAN.

    <Quidway> system-view
    [Quidway] sysname Switch
    [Switch] vlan 10
    [Switch-vlan10] quit
    [Switch] interface gigabitethernet 1/0/1
    [Switch-GigabitEthernet1/0/1] port hybrid pvid vlan 10
    [Switch-GigabitEthernet1/0/1] port hybrid untagged vlan 10
    [Switch-GigabitEthernet1/0/1] quit
    [Switch] interface gigabitethernet 3/0/3
    [Switch-GigabitEthernet3/0/3] port hybrid pvid vlan 10
    [Switch-GigabitEthernet3/0/3] port hybrid untagged vlan 10
    [Switch-GigabitEthernet3/0/3] quit

  2. Enable IGMP snooping.

    # Enable IGMP snooping globally.

    [Switch] igmp-snooping enable

    # Enable IGMP snooping in VLAN 10.

    [Switch] vlan 10
    [Switch-vlan10] igmp-snooping enable
    [Switch-vlan10] quit

  3. Configure an IGMP snooping SSM policy.

    # Create an ACL, and configure a rule that allows hosts to receive data of multicast group 225.1.1.1.

    [Switch] acl number 2008
    [Switch-acl-basic-2008] rule 5 permit source 225.1.1.1 0
    [Switch-acl-basic-2008] quit
    

    # Apply the SSM mapping policy in the VLAN and treat the multicast group 225.1.1.1 as a member in the SSM groups.

    [Switch] vlan 10 
    [Switch-vlan10] igmp-snooping ssm-policy 2008
    

  4. Enable SSM mapping.

    # Configure the Switch to run IGMPv3, enable SSM mapping, and configure a mapping between the multicast group 225.1.1.1 and the source IP address 10.10.1.1.

    [Switch-vlan10] igmp-snooping version 3
    [Switch-vlan10] igmp-snooping ssm-mapping enable 
    [Switch-vlan10] igmp-snooping ssm-mapping 225.1.1.1 32 10.10.1.1
    [Switch-vlan10] quit

  5. Verify the configuration.

    # Check the IGMP snooping configuration in the VLAN.

    <Switch> display igmp-snooping vlan configuration
     IGMP Snooping Configuration for VLAN 10
         igmp-snooping enable
         igmp-snooping version 3
         igmp-snooping ssm-mapping enable
         igmp-snooping ssm-policy 2008
         igmp-snooping ssm-mapping 225.1.1.1 255.255.255.255 10.10.1.1

    An SSM mapping policy has been configured in VLAN 10.

    # Check the Layer 2 multicast forwarding table.

    <Switch> display l2-multicast forwarding-table vlan 10 
    VLAN ID : 10, Forwarding Mode : IP                                          
    ----------------------------------------------------------------------------
                         (Source, Group)    Interface                   Out-Vlan
    ----------------------------------------------------------------------------
                            Router-port     GigabitEthernet3/0/3           10
                 (10.10.1.1, 225.1.1.1)     GigabitEthernet1/0/1           10
                                            GigabitEthernet3/0/3           10
                 (10.10.2.1, 225.1.1.1)     Stream                         10
                                            GigabitEthernet3/0/3           10
    ----------------------------------------------------------------------------
    Total Group(s) : 1

    The command output shows that a mapping entry (10.10.1.1, 225.1 .1.1) has been generated on the Switch. The mapping entry indicates that the data is sent by Source1.

    NOTE:

    The preceding stream entries are triggered by unknown streams that are generated because user hosts have no order for services delivered from multicast source 10.10.2.1.

Configuration Files

  • Configuration file of the Switch

    #
    sysname Switch
    #
    vlan batch 10
    #
    igmp-snooping enable
    #
    acl number 2008
     rule 5 permit source 225.1.1.1 0
    #
    vlan 10
     igmp-snooping enable
     igmp-snooping ssm-mapping enable
     igmp-snooping version 3
     igmp-snooping ssm-policy 2008
     igmp-snooping ssm-mapping 225.1.1.1 255.255.255.255 10.10.1.1
    #
    interface GigabitEthernet1/0/1
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10
    #
    interface GigabitEthernet3/0/3
     port hybrid pvid vlan 10
     port hybrid untagged vlan 10 
    #
    return 

10.11  Common Misconfigurations

This section describes common faults caused by incorrect IGMP snooping configurations and provides the troubleshooting procedure.

10.11.1  Layer 2 Multicast Packets Cannot Be Forwarded

Fault Description

Multicast packets can be forwarded normally when IGMP snooping is not configured. However, users cannot receive multicast packets after IGMP snooping is configured.

Procedure

  1. Check whether the IGMP snooping version configured on the device is earlier than that running on user hosts.

    If the IGMP snooping version configured on the device is earlier than that running on user hosts, the device only forward IGMP Report messages to router ports and does not generate group member ports and forwarding entries.

    Run the display igmp-snooping configuration command to check the IGMP snooping configuration. If the IGMP snooping version configured on the device is earlier than that running on user hosts, run the igmp-snooping version version command to make the device run the same IGMP version as user hosts.

  2. Check whether the general query interval configured on the local device is the same as that configured on the upstream device.

    If the general query interval on the local device is smaller than the general query interval on the upstream IGMP querier or IGMP snooping device, the local device may mistakenly age out some IGMP snooping entries that are still in use. As a result, multicast packets matching these entries cannot be forwarded.

    Run the display igmp-snooping command to check IGMP snooping parameters. If the general query interval on the local device is smaller than the general query interval on the upstream IGMP querier or IGMP snooping device, run the igmp-snooping query-interval query-interval command to increase the IGMP snooping general query interval. It is recommended that the upstream and downstream devices use the same general query interval.

    Table 10-3 lists the default general query interval values on Huawei S series switches.
    Table 10-3  Default general query interval values
    Feature Default Value on Modular Switches Default Value on Fixed Switches
    IGMP 60s 60s
    IGMP snooping 60s 125s

  3. Check whether router port dynamic learning is disabled.

    The switch does not listen to IGMP Query messages in a VLAN after router port dynamic learning is disabled in the VLAN.

    Run the display igmp-snooping configuration command to check whether router port dynamic learning is disabled. If the command output contains "undo igmp-snooping router-learning", run the igmp-snooping router-learning command to enable dynamic learning of router ports in the VLAN.

  4. Check whether fast leave for member ports is enabled.

    Configure fast leave in a VLAN only when each interface in the VLAN connects to only one host. If a member port is connected to multiple hosts and fast leave for member ports is enabled in the VLAN, the switch immediately deletes the forwarding entry of the member port after receiving an IGMP Leave message from the member port, and does not send a Group-Specific Query message. Therefore, multicast packets cannot be forwarded.

    Run the display igmp-snooping configuration command to check whether fast leave for member ports is enabled. If the command output contains "igmp-snooping prompt-leave", run the undo igmp-snooping prompt-leave command in the VLAN view to disable the fast leave function.

  5. Check whether the Router-Alert option is configured.

    If the Router-Alert option is configured, the switch checks the Option field of IGMP messages to discard messages without the Router-Alert option.

    Run the display igmp-snooping configuration command to check whether the Router-Alert option is configured. If the command output contains "igmp-snooping require-router-alert", run the undo igmp-snooping require-router-alert command in the VLAN view to delete the related configuration.

  6. Check whether a multicast group policy is configured.

    The multicast group policy limits the multicast groups that the hosts in a VLAN can join. Run the display igmp-snooping configuration command to verify the configuration of multicast group policy. If an ACL rule is configured, run the display acl command to verify the configuration of ACL rule.

  7. Check whether the Layer 2 multicast filtering function is configured.

    If the Layer 2 multicast filtering function is configured on the interface, the interface discards the UDP packets from the specified VLAN.

    Run the undo multicast-source-deny command in the physical interface view to disable the Layer 2 multicast filtering function.

10.11.2  The Multicast Group Policy Does Not Take Effect

Fault Description

A multicast policy is configured on the switch to allow the hosts to join the specified multicast groups. However, the hosts can still receive multicast data sent to other multicast groups.

Procedure

  1. Run the display acl command to check whether the ACL rules conflict with the multicast group policy.
  2. Run the display igmp-snooping configuration command to check whether a correct multicast group policy is applied in the VLAN. If not, run the igmp-snooping group-policy command to apply a correct multicast group policy in the VLAN.
  3. Run the display current-configuration | include drop-unknown command to check whether the switch is enabled to discard unknown multicast packets. If not, run the multicast drop-unknown command to enable the switch to discard unknown multicast packets.