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Multicast is the network layer technique used to transmit the data packets from one host to the selected hosts among the group of hosts. However, at the lower layer the switch broadcasts the multicast traffic on all ports, even if only one host wants to receive it. IGMP Snooping is used to forward IPv4 multicast traffic only to the desired host.
When IGMP snooping is enabled on the switch, it snoops (detects) the IGMP messages exchanged between the IPv4 router and the multicast hosts attached on the interface and maintains a table that restricts IPv4 multicast traffic dynamically forward only to those ports that want to receive it.
The following configuration is a prerequisite for this configuration:
1. Configure VLAN, please refer to the article VLAN Creation on Sx500 Series Stackable Switches for this configuration.
2. Enable Bridge Multicast Filtering, please refer to the article, Configuration of Multicast Properties on Sx500 Series Stackable Switches for this configuration.
This article explains how to configure IGMP Snooping and how to copy the IGMP configuration from one VLAN to the other on Sx500 Series Stackable Switches.
• Sx500 Series Stackable Switches
Configuration of IGMP Snooping
Step 1. Log in to the Switch Configuration Utility and choose Multicast > IGMP Snooping. The IGMP Snooping page opens:
Step 2. Check the Enable check box of IGMP Snooping Status to enable the switch to determine the hosts that have requested to receive multicast traffic.
Step 3. Click Apply to save the settings.
Step 4. Click the radio button of the desired VLAN ID for which the IGMP snooping configuration needs to be edited.
Note: IGMP Snooping is allowed only on static VLANs (a VLAN that is manually configured by VLAN ID and port assignments) and not on a dynamic VLAN (a VLAN that is dynamically assigned to the host by the switch when it gets connected. This operation requires the physical addresses of the hosts to be stored on the database of the switch some point prior).
Step 5. Click Edit to configure IGMP snooping. The Edit IGMP Snooping window appears.
Step 6. (Optional) Choose the desired VLAN ID from the VLAN ID drop-down list.
Step 7. Check the Enable check box in the IGMP Snooping Status field to determine which hosts under the chosen VLAN have requested to send the multicast traffic. The current status of IGMP snooping is displayed in the Operational IGMP Snooping Status field.
Step 8. (Optional) To enable the multicast router to learn automatically about the ports that are connected to it check the Enable check box of MRouter Ports Auto Learn.
Step 9. Enter the desired value in the following fields if the values need to be changed.
• Query Robustness — The robustness variable that indicates the number of MLD queries that the switch sends before it deletes a host that does not respond. The value ranges from 1 to 7. The default value is 2.
• Query Interval — The time interval between the query messages sent by the switch which ranges from 30 to 18000 seconds. The default time is 125 seconds.
• Query Max Response Interval — The delay which is used to determine the maximum response code inserted into the general queries. The time ranges from 5 to 20 seconds. The default is 10 seconds.
• Last Member Query Counter — The number of group-specific query messages sent before the switch assumes that there are no members of the host group to be queried on the interface. Click one of the following radio buttons:
– Use Default — The value equals the value defined in the Query Robustness field.
– User Defined — Enter the desired value that ranges from 1 to 7 in the User Defined field.
• Last Member Query Interval — The time interval that the switch waits to receive a response from a group-specific message. The time ranges from 100 to 25500 ms and the default is 1000 ms.
Step 10. (Optional) To decrease the time taken by the switch to block the MLD traffic that does not belong to its member port check the Enable check box in the Immediate Leave field.
Step 11. Check the Enable check box in the IGMP Querier Status field to enable the IGMP querier on the switch. The IGMP querier is usually the switch which queries, and is used to allow IGMP on a subnet which is given.
Step 12. If the source IP address of the administrative querier needs to be generated automatically, click the Auto radio button in the Administrative Querier Source IP Address field. Otherwise, click the User Defined radio button and choose the desired IP address from the drop-down list.
Step 13. Click radio button of the desired IGMP version in the IGMP Querier Version field.
Step 14. Click Apply to save the settings.
Copy IGMP Snooping Configuration Settings
Follow the steps given below to copy the IGMP snooping configuration settings from one VLAN to another VLAN.
Step 1. Click the radio button of the desired VLAN ID. This is the VLAN ID on which IGMP snooping is defined.
Step 2. Click Copy Settings to copy the IGMP snooping configuration. The Copy IGMP Snooping window appears.
Step 3. Enter the desired VLAN ID(s) or range(s) of VLAN IDs in the provided field to which the configuration needs to be copied.
Step 4. Click Apply to save the settings.