JavaScript is required to for searching.
Skip Navigation Links
Exit Print View
Sun Ethernet Fabric Operating System

IGS Administration Guide

search filter icon
search icon

Document Information

Using This Documentation

Product Notes

Related Documentation

Acronyms and Abbreviations

CLI Command Modes


Support and Accessibility

IGS Overview

IGS Protocol Description

Topology Example

Configuration Prerequisites

Default Settings

Configuring IGS

Enabling and Disabling IGS

Enable IGS Globally

Enable IGS on a Specific VLAN Interface

Disable IGS

Configure Multicast Forwarding Mode

Configure the IGS Version

Configuring a Multicast Router Port

Enable Multicast Router Port

Disable a Multicast Router Port

Configure the Multicast Router Port Time-Out Value

Configuring IGS Querier Settings

Enable IGS as a Querier

Configure the IGMP Snooping Query Interval

Configuring Proxy Reporting

Disable Proxy Reporting

Enable Proxy Reporting

Configuring the Port-Purge Interval

Set the Port-Purge Interval

Reset the Port-Purge Interval

Configuring Leave Processing

Enable the Fast Leave Process

Disable the Fast Leave Process

Configuring the Report Suppression Interval

Enable the Report Suppression Interval

Disable the Report Suppression Interval

Configuring the Group Query Interval Value

Set the Group Query Interval Value

Reset the Group Query Interval

Configuring the Group Retry Count Value

Set the Group Retry Count Value

Reset the Group Retry Count Value

Configuring Report Forwarding

Enable Report Forwarding

Disable Report Forwarding

Reset Report Forwarding to the Default Value

Clearing the Snooping Statistics

Clear the Statistics for a Specific VLAN

Clear the Statistics for All VLANs

Configuring the General Query Transmission Option

Enable the General Query Transmission Option

Disable the General Query Transmission Option

Display Statistics

Flow-Based Configurations

Flow-Based Configuration Example

Configuration Parameters

Configure the MAC-Based Multicast Forwarding Mode

Configure the IP-Based Multicast Forwarding Mode

Configure a Static Router Port

Configure the IGS Version

Configure Queriers in Flow-Based Configurations

Configure Proxy Reporting in Flow-Based Configurations

IGS Protocol Description

IGS enables a switch to snoop or capture information from IGMP packets being sent back and forth between hosts and a router. Based on this information, the switch adds or deletes the multicast addresses from its address table, thereby enabling or disabling multicast traffic from flowing to individual host ports. In subnets where IGMP is configured, IGS manages multicast traffic at layer 2.

IGMP (on a router) periodically sends out IGMP general queries. When IGS is enabled, the switch responds to the IGMP queries with only one IGMP join request per multicast group. The switch creates one entry per subnet in the layer 2 forwarding table for each layer 2 multicast group from which it receives an IGMP join request. Hosts interested in the multicast traffic send IGMP join requests and are added to the forwarding table entry.

Layer 2 multicast groups learned through IGS are dynamic. However, it is possible to statically configure layer 2 multicast groups using the ip igmp snooping static command. If group membership for a multicast group address is specified statically, then the configured static setting supersedes any automatic manipulation by IGS. Multicast group membership lists consist of both user-defined settings and IGS.

Groups with IP addresses in the range are reserved for routing control packets and are flooded to all the forwarding ports of the VLAN. These addresses map to the multicast MAC address range 0100.5E00.0001 to 0100.5E00.00FF.

A host connected to a layer 2 interface that needs to join an IP multicast group, sends an IGMP join request specifying the IP multicast group. A host that needs to leave the multicast group can either ignore the periodic IGMP general queries or can send an IGMP leave message. When the switch receives an IGMP leave message from a host, the switch sends out an IGMP group-specific query to determine whether any device connected to that interface is interested in the traffic for the specific multicast group. The switch then updates the table entry for that layer 2 multicast group so that only those hosts interested in receiving multicast traffic for the group are listed.

When a host connected to the switch wants to join an IP multicast group, the host sends an unsolicited IGMP join message, specifying the IP multicast group to join. Alternatively, when the switch receives a general query from the router, the switch forwards the query to all ports in the VLAN. Hosts wanting to join the multicast group respond by sending a join message to the switch. The switch creates a multicast forwarding-table entry for the group if it is not already present.

The switch also adds the interface from which the join message was received to the forwarding table entry. After the forwarding table entry is created, the host associated with that interface receives multicast traffic for that multicast group.