3.2. Configuring IGMP with CLI

This section provides information to configure IGMP using the command line interface.

3.2.1. IGMP Configuration Overview

The routers use IGMP to manage membership for a given multicast session. IGMP is not enabled by default. When enabled, at least one interface must be specified in the IGMP context as IGMP is an interface function. Creating an interface enables IGMP. Traffic can only flow away from the router to an IGMP interface and to and from a PIM interface. A router directly connected to a source must have PIM enabled on the interface to that source. The traffic travels in a network from PIM interface to PIM interface and arrives finally on an IGMP enabled interface.

The IGMP CLI context allows you to specify an existing IP interface and modify the interface-specific parameters. Static IGMP group memberships can be configured to test multicast forwarding without a receiver host. When IGMP static group membership is enabled, data is forwarded to an interface without receiving membership reports from host members.

When static IGMP group entries on point-to-point links that connect routers to a rendezvous point (RP) are configured, the static IGMP group entries do not generate join messages toward the RP. When a host wants to receive multicast sessions it sends a join message for each multicast group it wants to join. Then, a leave message may be sent for each multicast group it no longer wishes to participate with.

A multicast router keeps a list of multicast group memberships for each attached network, and an interval timer for each membership. Hosts issue a Multicast Group Membership Report when they want to receive a multicast session. The reports are sent to all multicast routers.

3.2.2. Basic IGMP Configuration

Perform the following basic multicast configuration tasks:

  1. Enable IGMP (required)
  2. Configure IGMP interfaces (required)
  3. Specify IGMP version on the interface (optional)
  4. Configure static (S,G)/(*,G) (optional)
  5. Configure SSM translation (optional)

3.2.3. Configuring IGMP Parameters

3.2.3.1. Enabling IGMP

Use the following CLI syntax to enable IGMP.

CLI Syntax:
config>router# igmp

The following example displays the detailed output when IGMP is enabled.

A:LAX>>config>router# info detail
...
#------------------------------------------
echo "IGMP Configuration"
#------------------------------------------
        igmp
            query-interval 125
            query-last-member-interval 1
            query-response-interval 10
            robust-count 2
            no shutdown
        exit
#------------------------------------------
A:LAX>>config>system#

3.2.3.2. Configuring an IGMP Interface

To configure an IGMP interface:

CLI Syntax:
config>router# igmp
interface ip-int-name
max-groups value
import policy-name
version version
no shutdown

Use the following CLI syntax to configure IGMP interfaces:

Example:
config>router#
config>router>igmp# interface "lax-vls"
config>router>igmp>if? no shutdown
config>router>igmp>if# exit
config>router>igmp# interface "p1-ix"
config>router>igmp>if? no shutdown
config>router>igmp>if# exit
config>router>igmp# interface "lax-sjc"
config>router>igmp>if? no shutdown
config>router>igmp>if# exit

The following example displays the IGMP configuration:

A:LAX>config>router>igmp# info
----------------------------------------------
        interface "lax-sjc"
        exit
        interface "lax-vls"
        exit
        interface "p1-ix"
        exit
----------------------------------------------
A:LAX>config>router>igmp# exit

3.2.3.3. Configuring Static Parameters

To add an IGMP static multicast source:

CLI Syntax:
config>router# igmp
interface ip-int-name
no shutdown
static
group grp-ip-address
source ip-address

Use the following CLI syntax to configure static group addresses and source addresses for the SSM translate group ranges:

Example:
config>router>igmp# interface lax-vls
config>router>igmp>if# static
config>router>igmp>if>static# group 239.255.0.2
config>router>igmp>if>static>group# source 172.22.184.197
config>router>igmp>if>static>group# exit
config>router>igmp>if>static# exit
config>router>igmp>if# exit

The following example displays the configuration:

A:LAX>config>router>igmp# info
----------------------------------------------
        interface "lax-sjc"
        exit
        interface "lax-vls"
            static
                group 239.255.0.2
                    source 172.22.184.197
                exit
            exit
        exit
        interface "p1-ix"
        exit
----------------------------------------------
A:LAX>config>router>igmp#

To add an IGMP static starg entry:

CLI Syntax:
config>router# igmp
interface ip-int-name
no shutdown
static
group grp-ip-address
starg

Use the following CLI syntax to configure static group addresses and add a static (*,G) entry:

Example:
config>router>igmp# interface lax-sjc
config>router>igmp>if# static
config>router>igmp>if>static# group 239.1.1.1
config>router>igmp>if>static>group# starg
config>router>igmp>if>static>group# exit
config>router>igmp>if>static# exit
config>router>igmp>if# exit
config>router>igmp#

The following example displays the configuration:

A:LAX>config>router>igmp# info
----------------------------------------------
        interface "lax-sjc"
            static
                group 239.1.1.1
                    starg
                exit
            exit
        exit
        interface "lax-vls"
            static
                group 239.255.0.2
                    source 172.22.184.197
                exit
            exit
        exit
        interface "p1-ix"
        exit
----------------------------------------------
A:LAX>config>router>igmp#

3.2.3.4. Configuring SSM Translation

To configure IGMP parameters:

CLI Syntax:
config>router# igmp
ssm-translate
grp-range start end
source ip-address

The following example displays the command usage to configure IGMP parameters:

Example:
config>router# igmp
config>router>igmp# ssm-translate
config>router>igmp>ssm# grp-range 239.255.0.1 239.2.2.2
config>router>igmp>ssm>grp-range# source 10.1.1.1

The following example displays the SSM translation configuration:

A:LAX>config>router>igmp# info
----------------------------------------------
        ssm-translate
            grp-range 239.255.0.1 239.2.2.2
                source 10.1.1.1
            exit
        exit
        interface "lax-sjc"
            static
                group 239.1.1.1
                    starg
                exit
            exit
        exit
        interface "lax-vls"
            static
                group 239.255.0.2
                    source 172.22.184.197
                exit
            exit
        exit
        interface "p1-ix"
        exit
----------------------------------------------
A:LAX>config>router>igmp# exit

3.2.4. Disabling IGMP

Use the following CLI syntax to disable IGMP.

CLI Syntax:
config>router#
igmp
shutdown

The following example displays the command usage to disable multicast:

Example:
config>router# igmp
config>router>igmp# shutdown
config>router>igmp# exit

The following example displays the configuration output:

A:LAX>config>router# info
----------------------------------------------
...
#------------------------------------------
echo "IGMP Configuration"
#------------------------------------------
        igmp
            shutdown
            ssm-translate
                grp-range 239.255.0.1 239.2.2.2
                    source 10.1.1.1
                exit
            exit
            interface "lax-sjc"
                static
                    group 239.1.1.1
                        starg
                    exit
                exit
            exit
            interface "lax-vls"
                static
                    group 239.255.0.2
                        source 172.22.184.197
                    exit
                exit
            exit
            interface "p1-ix"
            exit
        exit
#------------------------------------------