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Prerequisites for Configuring IGMP Snooping
Prerequisites for
IGMP Snooping
Observe these guidelines when
configuring the IGMP snooping querier:
Configure the VLAN in global
configuration mode.
Configure an IP address on
the VLAN interface. When enabled, the IGMP snooping querier uses the IP address
as the query source address.
If there is no IP address
configured on the VLAN interface, the IGMP snooping querier tries to use the
configured global IP address for the IGMP querier. If there is no global IP
address specified, the IGMP querier tries to use the VLAN
switch virtual interface (SVI) IP address (if
one exists). If there is no SVI IP address, the
switch uses the first available IP address
configured on the
switch. The first IP address available
appears in the output of the
show ip interface privileged EXEC command. The
IGMP snooping querier does not generate an IGMP general query if it cannot find
an available IP address on the
switch.
The IGMP snooping querier
supports IGMP Versions 1 and 2.
When administratively
enabled, the IGMP snooping querier moves to the nonquerier state if it detects
the presence of a multicast router in the network.
When it is administratively enabled, the IGMP snooping querier moves to the operationally disabled state if IGMP snooping
is disabled in the VLAN.
Layer 3 multicast is not supported.
MAC based snooping is supported in hardware.
Restrictions for Configuring IGMP Snooping
Restrictions for IGMP Snooping
The following are the restrictions for IGMP snooping:
IGMP report suppression is supported only when the multicast query has IGMPv1 and IGMPv2 reports. This feature is not supported
when the query includes IGMPv3 reports.
The IGMP configurable leave time is only supported on hosts running IGMP Version 2. IGMP version 2 is the default version
for the switch.
The actual leave latency in the network is usually the configured leave time. However, the leave time might vary around the
configured time, depending on real-time CPU load conditions, network delays and the amount of traffic sent through the interface.
The IGMP throttling action restriction can be applied only to Layer 2 ports. You can use ip igmp max-groups action replace interface configuration command on a logical EtherChannel interface but cannot use it on ports that belong to an EtherChannel
port group.
When the maximum group limitation is set to the default (no maximum), entering the ip igmp max-groups action {deny | replace} command has no effect.
If you configure the throttling action and set the maximum group limitation after an interface has added multicast entries
to the forwarding table, the forwarding-table entries are either aged out or removed, depending on the throttling action.
Information About IGMP Snooping
IGMP Snooping
Layer 2
switches can use IGMP snooping to constrain the
flooding of multicast traffic by dynamically configuring Layer 2 interfaces so
that multicast traffic is forwarded to only those interfaces associated with IP
multicast devices. As the name implies, IGMP snooping requires the LAN
switch to snoop on the IGMP transmissions
between the host and the router and to keep track of multicast groups and
member ports. When the
switch receives an IGMP report from a host
for a particular multicast group, the
switch adds the host port number to the
forwarding table entry; when it receives an IGMP Leave Group message from a
host, it removes the host port from the table entry. It also periodically
deletes entries if it does not receive IGMP membership reports from the
multicast clients.
Note
For more information on IP
multicast and IGMP, see RFC 1112 and RFC 2236.
The multicast router
sends out periodic general queries to all VLANs. All hosts interested in this multicast traffic send join requests and
are added to the forwarding table entry. The switch creates one entry per VLAN in the IGMP snooping IP multicast forwarding table for each group from which it receives an IGMP
join request.
The
switch supports IP multicast group-based
bridging, instead of MAC-addressed based groups. With multicast MAC
address-based groups, if an IP address being configured translates (aliases) to
a previously configured MAC address or to any reserved multicast MAC addresses
(in the range 224.0.0.xxx), the command fails. Because the
switch uses IP multicast groups, there are no
address aliasing issues.
The IP multicast groups
learned through IGMP snooping are dynamic. However, you can statically
configure multicast groups by using the
ip igmp snooping vlan
vlan-id staticip_addressinterfaceinterface-id
global configuration command. If you specify group membership for a multicast
group address statically, your setting supersedes any automatic manipulation by
IGMP snooping. Multicast group membership lists can consist of both
user-defined and IGMP snooping-learned settings.
You can configure an IGMP
snooping querier to support IGMP snooping in subnets without multicast
interfaces because the multicast traffic does not need to be routed.
If a port spanning-tree, a
port group, or a VLAN ID change occurs, the IGMP snooping-learned multicast
groups from this port on the VLAN are deleted.
These sections describe IGMP snooping characteristics:
IGMP Versions
The
switch supports IGMP version 1, IGMP version
2, and IGMP version 3. These versions are interoperable on the
switch. For example, if IGMP snooping is
enabled and the querier's version is IGMPv2, and the
switch receives an IGMPv3 report from a host,
then the
switch can forward the IGMPv3 report to the
multicast router.
An IGMPv3
switch can receive messages from and forward
messages to a device running the Source Specific Multicast (SSM) feature.
Joining a Multicast Group
Router A sends a general query to the
switch, which forwards the query to ports 2
through 5, all of which are members of the same VLAN. Host 1 wants to join
multicast group 224.1.2.3 and multicasts an IGMP membership report (IGMP join
message) to the group. The
switch CPU uses the information in the IGMP
report to set up a forwarding-table entry that includes the port numbers
connected to Host 1 and to the router.
Table 1. IGMP Snooping Forwarding
Table
Destination Address
Type of Packet
Ports
224.1.2.3
IGMP
1, 2
The
switch hardware can distinguish IGMP
information packets from other packets for the multicast group. The information
in the table tells the switching engine to send frames addressed to the
224.1.2.3 multicast IP address that are not IGMP packets to the router and to
the host that has joined the group.
Table 2. Updated IGMP Snooping
Forwarding Table
Destination Address
Type of Packet
Ports
224.1.2.3
IGMP
1, 2, 5
Leaving a Multicast Group
The router sends periodic multicast general queries, and the switch forwards these queries through all ports in the VLAN. Interested hosts respond to the queries. If at least one host in the
VLAN wants to receive multicast traffic, the router continues forwarding the multicast traffic to the VLAN. The switch forwards multicast group traffic only to those hosts listed in the forwarding table for that IP multicast group maintained
by IGMP snooping.
When hosts want to leave a multicast group, they can silently leave, or they can send a leave message. When the switch receives a leave message from a host, it sends a group-specific query to learn if any other devices connected to that interface
are interested in traffic for the specific multicast group. The switch then updates the forwarding table for that MAC group so that only those hosts interested in receiving multicast traffic for
the group are listed in the forwarding table. If the router receives no reports from a VLAN, it removes the group for the
VLAN from its IGMP cache.
Immediate Leave
The
switch uses IGMP snooping Immediate Leave to
remove from the forwarding table an interface that sends a leave message
without the
switch sending group-specific queries to the
interface. The VLAN interface is pruned from the multicast tree for the
multicast group specified in the original leave message. Immediate Leave
ensures optimal bandwidth management for all hosts on a switched network, even
when multiple multicast groups are simultaneously in use.
Immediate Leave is only
supported on IGMP version 2 hosts. IGMP version 2 is the default version for
the
switch.
Note
You should use the Immediate
Leave feature only on VLANs where a single host is connected to each port. If
Immediate Leave is enabled on VLANs where more than one host is connected to a
port, some hosts may be dropped inadvertently.
IGMP Configurable-Leave Timer
You can configure the time
that the
switch waits after sending a group-specific
query to determine if hosts are still interested in a specific multicast group.
The IGMP leave response time can be configured from 100 to 32767 milliseconds.
IGMP Report Suppression
Note
IGMP report suppression is supported only when the multicast query has IGMPv1 and IGMPv2 reports. This feature is not supported
when the query includes IGMPv3 reports.
The switch uses IGMP report suppression to forward only one IGMP report per multicast router query to multicast devices. When IGMP
report suppression is enabled (the default), the switch sends the first IGMP report from all hosts for a group to all the multicast routers. The switch does not send the remaining IGMP reports for the group to the multicast routers. This feature prevents duplicate reports
from being sent to the multicast devices.
If the multicast router query includes requests only for IGMPv1 and IGMPv2 reports, the switch forwards only the first IGMPv1 or IGMPv2 report from all hosts for a group to all the multicast routers.
If the multicast router query also includes requests for IGMPv3 reports, the switch forwards all IGMPv1, IGMPv2, and IGMPv3 reports for a group to the multicast devices.
If you disable IGMP report suppression, all IGMP reports are forwarded to the multicast routers.
Default IGMP Snooping Configuration
This table displays
the default IGMP snooping configuration for the
switch.
In some environments, for
example, metropolitan or multiple-dwelling unit (MDU) installations, you might
want to control the set of multicast groups to which a user on a
switch port can belong. You can control the
distribution of multicast services, such as IP/TV, based on some type of
subscription or service plan. You might also want to limit the number of
multicast groups to which a user on a
switch port can belong.
With the IGMP filtering
feature, you can filter multicast joins on a per-port basis by configuring IP
multicast profiles and associating them with individual
switch ports. An IGMP profile can contain one
or more multicast groups and specifies whether access to the group is permitted
or denied. If an IGMP profile denying access to a multicast group is applied to
a
switch port, the IGMP join report requesting
the stream of IP multicast traffic is dropped, and the port is not allowed to
receive IP multicast traffic from that group. If the filtering action permits
access to the multicast group, the IGMP report from the port is forwarded for
normal processing. You can also set the maximum number of IGMP groups that a
Layer 2 interface can join.
IGMP filtering controls only group-specific query and membership reports, including join and leave reports. It does not control
general IGMP queries. IGMP filtering has no relationship with the function that directs the forwarding of IP multicast traffic.
IGMP filtering applies only
to the dynamic learning of IP multicast group addresses, not static
configuration.
With the IGMP throttling
feature, you can set the maximum number of IGMP groups that a Layer 2 interface
can join. If the maximum number of IGMP groups is set, the IGMP snooping
forwarding table contains the maximum number of entries, and the interface
receives an IGMP join report, you can configure an interface to drop the IGMP
report or to replace the randomly selected multicast entry with the received
IGMP report.
Note
IGMPv3 join and leave
messages are not supported on
switches running IGMP filtering.
Default IGMP Filtering and Throttling Configuration
This table displays
the default IGMP filtering and throttling configuration for the
switch.
Table 4. Default IGMP Filtering
Configuration
Feature
Default Setting
IGMP filters
None applied.
IGMP maximum number of IGMP
groups
No maximum set.
Note
When the maximum number of groups is in the
forwarding table, the default IGMP throttling action is to deny the IGMP
report.
IGMP profiles
None defined.
IGMP profile action
Deny the range addresses.
How to Configure IGMP Snooping
Enabling or Disabling IGMP Snooping on a
Switch
When IGMP snooping is
globally enabled or disabled, it is also enabled or disabled in all existing
VLAN interfaces. IGMP snooping is enabled on all VLANs by default, but can be
enabled and disabled on a per-VLAN basis.
Global IGMP snooping
overrides the VLAN IGMP snooping. If global snooping is disabled, you cannot
enable VLAN snooping. If global snooping is enabled, you can enable or disable
VLAN snooping.
Follow these steps
to globally enable IGMP snooping on the
switch:
SUMMARY STEPS
enable
configureterminal
ip igmp
snooping
end
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
ip igmp
snooping
Example:
Switch(config)# ip igmp snooping
Globally enables
IGMP snooping in all existing VLAN interfaces.
Note
To globally
disable IGMP snooping on all VLAN interfaces, use the
no ip igmp snooping
global configuration command.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Enabling or Disabling IGMP Snooping on a VLAN Interface
Follow these steps to enable IGMP snooping on a VLAN interface:
SUMMARY STEPS
enable
configureterminal
ip igmp snooping
vlanvlan-id
end
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
ip igmp snooping
vlanvlan-id
Example:
Switch(config)# ip igmp snooping vlan 7
Enables IGMP
snooping on the VLAN interface. The VLAN ID range is 1 to 1001 and 1006 to
4094.
IGMP snooping
must be globally enabled before you can enable VLAN snooping.
Note
To disable IGMP
snooping on a VLAN interface, use the
no ip igmp snooping vlan
vlan-id global configuration command for the specified VLAN
number.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring a Multicast Router Port
Perform these steps to add a
multicast router port (enable a static connection to a multicast router) on the
switch.
Note
Static connections to
multicast routers are supported only on
switch ports.
SUMMARY STEPS
enable
configureterminal
ip igmp snooping
vlanvlan-idmrouter interfaceinterface-id
end
show ip igmp snooping
mrouter [vlanvlan-id]
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
ip igmp snooping
vlanvlan-idmrouter interfaceinterface-id
Example:
Switch(config)# ip igmp snooping vlan 5 mrouter interface gigabitethernet0/1
Specifies the
multicast router VLAN ID and the interface to the multicast router.
The VLAN ID range
is 1 to 1001 and 1006 to 4094.
The interface can
be a physical interface or a port channel. The port-channel range is 1 to 128.
Note
To remove a
multicast router port from the VLAN, use the
no ip igmp snooping
vlanvlan-idmrouter
interfaceinterface-idglobal configuration command.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show ip igmp snooping
mrouter [vlanvlan-id]
Example:
Switch# show ip igmp snooping mrouter vlan 5
Verifies that IGMP
snooping is enabled on the VLAN interface.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring a Host Statically to Join a Group
Hosts or Layer 2 ports normally join multicast groups dynamically, but you can also statically configure a host on an interface.
Follow these steps to add a Layer 2 port as a member of a multicast group:
SUMMARY STEPS
enable
configureterminal
ip igmp snooping vlanvlan-idstaticmac_addressinterfaceinterface-id
end
show ip igmp snooping groups
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
ip igmp snooping vlanvlan-idstaticmac_addressinterfaceinterface-id
Example:
Switch(config)# ip igmp snooping vlan 105 static 0100.1212.0000 interface gigabitethernet0/1
Statically configures a Layer 2 port as a member of a multicast group:
vlan-id is the multicast group VLAN ID. The range is 1 to 1001 and 1006 to 4094.
mac-address is the group MAC address.
interface-id is the member port. It can be a physical interface or a port channel (1 to 6).
Note
To remove the Layer 2 port from the multicast group, use theno ip igmp snooping vlan vlan-idstaticmac-addressinterfaceinterface-id global configuration command.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show ip igmp snooping groups
Example:
Switch# show ip igmp snooping groups
Verifies the member port and the IP address.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Enabling IGMP Immediate Leave
When you enable IGMP
Immediate Leave, the
switch immediately removes a port when it
detects an IGMP Version 2 leave message on that port. You should use the
Immediate-Leave feature only when there is a single receiver present on every
port in the VLAN.
Note
Immediate Leave is supported
only on IGMP Version 2 hosts. IGMP Version 2 is the default version for the
switch.
SUMMARY STEPS
enable
configureterminal
ip igmp snooping
vlanvlan-idimmediate-leave
end
show ip igmp
snooping vlanvlan-id
end
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
ip igmp snooping
vlanvlan-idimmediate-leave
Example:
Switch(config)# ip igmp snooping vlan 21 immediate-leave
Enables IGMP
Immediate Leave on the VLAN interface.
Note
To disable
IGMP Immediate Leave on a VLAN, use the no ip igmp snooping vlanvlan-idimmediate-leave global configuration command.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show ip igmp
snooping vlanvlan-id
Example:
Switch# show ip igmp snooping vlan 21
Verifies that
Immediate Leave is enabled on the VLAN interface.
Step 6
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Configuring the IGMP Leave Timer
You can configure the leave time globally or on a per-VLAN basis.
Follow these steps to enable the IGMP configurable-leave timer:
SUMMARY STEPS
enable
configureterminal
ip igmp snooping
last-member-query-intervaltime
ip igmp snooping
vlanvlan-idlast-member-query-intervaltime
end
show ip igmp
snooping
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
ip igmp snooping
last-member-query-intervaltime
Example:
Switch(config)# ip igmp snooping last-member-query-interval 1000
Configures the
IGMP leave timer globally. The range is 100 to 32767 milliseconds.
The default leave
time is 1000 milliseconds.
Note
To globally
reset the IGMP leave timer to the default setting, use the no ip igmp snooping last-member-query-interval
global configuration command.
Step 4
ip igmp snooping
vlanvlan-idlast-member-query-intervaltime
Example:
Switch(config)# ip igmp snooping vlan 210 last-member-query-interval 1000
(Optional)
Configures the IGMP leave time on the VLAN interface. The range is 100 to 32767
milliseconds.
Note
Configuring the
leave time on a VLAN overrides the globally configured timer.
Note
To remove the
configured IGMP leave-time setting from the specified VLAN, use the
no ip igmp snooping
vlanvlan-idlast-member-query-interval global configuration
command.
Step 5
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 6
show ip igmp
snooping
Example:
Switch# show ip igmp snooping
(Optional)
Displays the configured IGMP leave time.
Step 7
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring the IGMP Snooping Querier
Follow these steps to enable
the IGMP snooping querier feature in a VLAN:
SUMMARY STEPS
enable
configureterminal
ip igmp snooping
querier
ip igmp snooping
querier addressip_address
ip igmp snooping
querier query-intervalinterval-count
Switch(config)# ip igmp snooping querier address 172.16.24.1
(Optional)
Specifies an IP address for the IGMP snooping querier. If you do not specify an
IP address, the querier tries to use the global IP address configured for the
IGMP querier.
Note
The IGMP snooping
querier does not generate an IGMP general query if it cannot find an IP address
on the
switch.
Step 5
ip igmp snooping
querier query-intervalinterval-count
Example:
Switch(config)# ip igmp snooping querier query-interval 30
(Optional) Sets
the interval between IGMP queriers. The range is 1 to 18000 seconds.
Switch(config)# ip igmp snooping querier tcn query interval 20
(Optional) Sets
the time between Topology Change Notification (TCN) queries. The count range is
1 to 10. The interval range is 1 to 255 seconds.
Step 7
ip igmp snooping
querier timer expirytimeout
Example:
Switch(config)# ip igmp snooping querier timer expiry 180
(Optional) Sets
the length of time until the IGMP querier expires. The range is 60 to 300
seconds.
Step 8
ip igmp snooping
querier versionversion
Example:
Switch(config)# ip igmp snooping querier version 2
(Optional) Selects
the IGMP version number that the querier feature uses. Select 1 or 2.
Step 9
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 10
show ip igmp
snooping vlanvlan-id
Example:
Switch# show ip igmp snooping vlan 30
(Optional)
Verifies that the IGMP snooping querier is enabled on the VLAN interface. The
VLAN ID range is 1 to 1001 and 1006 to 4094.
Step 11
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Disabling IGMP Report Suppression
Follow these steps to disable
IGMP report suppression:
SUMMARY STEPS
enable
configureterminal
no ip igmp
snooping report-suppression
end
show ip igmp
snooping
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
no ip igmp
snooping report-suppression
Example:
Switch(config)# no ip igmp snooping report-suppression
Disables IGMP
report suppression. When report suppression is disabled, all IGMP reports are
forwarded to the multicast routers.
IGMP report suppression is enabled by default.
When IGMP report supression is enabled, the
switch
forwards only one IGMP report per multicast router query.
Note
To re-enable
IGMP report suppression, use the ip igmp snooping
report-suppression global configuration command.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show ip igmp
snooping
Example:
Switch# show ip igmp snooping
Verifies that IGMP
report suppression is disabled.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring IGMP Profiles
Follow these steps to create an IGMP profile:
This task is optional.
SUMMARY STEPS
enable
configureterminal
ip igmp
profileprofile number
permit |
deny
rangeip multicast
address
end
show ip igmp
profileprofile number
show running-config
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
ip igmp
profileprofile number
Example:
Switch(config)# ip igmp profile 3
Assigns a number
to the profile you are configuring, and enters IGMP profile configuration mode.
The profile number range is 1 to 4294967295. When you are in IGMP profile
configuration mode, you can create the profile by using these commands:
deny—Specifies that matching addresses are denied;
this is the default.
exit—Exits
from igmp-profile configuration mode.
no—Negates a
command or returns to its defaults.
permit—Specifies that matching addresses are
permitted.
range—Specifies a range of IP addresses for the
profile. You can enter a single IP address or a range with a start and an end
address.
The default is for the
switch
to have no IGMP profiles configured.
Note
To delete a
profile, use the
no ip igmp profileprofile
number global configuration command.
Step 4
permit |
deny
Example:
Switch(config-igmp-profile)# permit
(Optional) Sets
the action to permit or deny access to the IP multicast address. If no action
is configured, the default for the profile is to deny access.
Step 5
rangeip multicast
address
Example:
Switch(config-igmp-profile)# range 229.9.9.0
Enters the IP
multicast address or range of IP multicast addresses to which access is being
controlled. If entering a range, enter the low IP multicast address, a space,
and the high IP multicast address.
You can use the
range command
multiple times to enter multiple addresses or ranges of addresses.
Note
To delete an
IP multicast address or range of IP multicast addresses, use the
no range ip multicast address
IGMP profile configuration command.
Step 6
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 7
show ip igmp
profileprofile number
Example:
Switch# show ip igmp profile 3
Verifies the
profile configuration.
Step 8
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 9
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Applying IGMP Profiles
To control access as defined
in an IGMP profile, you have to apply the profile to the appropriate
interfaces. You can apply IGMP profiles only to Layer 2 access ports; you
cannot apply IGMP profiles to routed ports or SVIs. You cannot apply profiles
to ports that belong to an EtherChannel port group. You can apply a profile to
multiple interfaces, but each interface can have only one profile applied to
it.
Follow these steps to apply an IGMP profile to a switch port:
SUMMARY STEPS
enable
configureterminal
interfaceinterface-id
ip igmp
filterprofile number
end
show running-config
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
interfaceinterface-id
Example:
Switch(config)# interface gigabitethernet0/1
Specifies the
physical interface, and enters interface configuration mode. The interface must
be a Layer 2 port that does not belong to an EtherChannel port group.
Step 4
ip igmp
filterprofile number
Example:
Switch(config-if)# ip igmp filter 321
Applies the
specified IGMP profile to the interface. The range is 1 to 4294967295.
Note
To remove a
profile from an interface, use theno ip
igmp filter
profile number interface configuration command.
Step 5
end
Example:
Switch(config-if)# end
Returns to
privileged EXEC mode.
Step 6
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 7
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Setting the Maximum Number of IGMP Groups
Follow these steps to set the
maximum number of IGMP groups that a Layer 2 interface can join:
Before you begin
This
restriction can be applied to Layer 2 ports only; you cannot set a maximum
number of IGMP groups on routed ports or SVIs. You also can use this command on
a logical EtherChannel interface but cannot use it on ports that belong to an
EtherChannel port group.
SUMMARY STEPS
enable
configureterminal
interfaceinterface-id
ip igmp
max-groupsnumber
end
show
running-config interfaceinterface-id
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
interfaceinterface-id
Example:
Switch(config)# interface gigabitethernet0/2
Specifies the
interface to be configured, and enters interface configuration mode. The
interface can be a Layer 2 port that does not belong to an EtherChannel group
or a EtherChannel interface.
Step 4
ip igmp
max-groupsnumber
Example:
Switch(config-if)# ip igmp max-groups 20
Sets the maximum
number of IGMP groups that the interface can join. The range is 0 to
4294967294. The default is to have no maximum set.
Note
To remove the maximum group limitation and return to the default of no maximum, use the no ip igmp max-groups interface configuration command.
Step 5
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 6
show
running-config interfaceinterface-id
Example:
Switch# interface gigabitethernet0/1
Verifies your
entries.
Step 7
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring the IGMP Throttling Action
After you set the maximum number of IGMP groups that a Layer 2 interface can
join, you can configure an interface to replace the existing group with the new
group for which the IGMP report was received.
Follow these steps to configure the throttling action when the maximum
number of entries is in the forwarding table:
SUMMARY STEPS
enable
configureterminal
interfaceinterface-id
ip igmp max-groups
action {deny |
replace}
end
show
running-config interfaceinterface-id
copy running-config
startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
interfaceinterface-id
Example:
Switch(config)# interface gigabitethernet0/1
Specifies the
physical interface to be configured, and enters interface configuration mode.
The interface can be a Layer 2 port that does not belong to an EtherChannel
group or an EtherChannel interface. The interface cannot be a trunk port.
Step 4
ip igmp max-groups
action {deny |
replace}
Example:
Switch(config-if)# ip igmp max-groups action replace
When an interface
receives an IGMP report and the maximum number of entries is in the forwarding
table, specifies the action that the interface takes:
deny—Drops the report. If you configure this
throttling action, the entries that were previously in the forwarding table are
not removed but are aged out. After these entries are aged out and the maximum
number of entries is in the forwarding table, the
switch
drops the next IGMP report received on the interface.
replace—Replaces the existing group with the new
group for which the IGMP report was received. If you configure this throttling
action, the entries that were previously in the forwarding table are removed.
When the maximum number of entries is in the forwarding table, the
switch
replaces a randomly selected entry with the received IGMP report.
To prevent the
switch
from removing the forwarding-table entries, you can configure the IGMP
throttling action before an interface adds entries to the forwarding table.
Note
To return to
the default action of dropping the report, use the
no ip igmp max-groups
action interface configuration command.
Step 5
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 6
show
running-config interfaceinterface-id
Example:
Switch# show running-config interface gigabitethernet0/1
Verifies your
entries.
Step 7
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Monitoring IGMP Snooping
Monitoring IGMP
Snooping Information
You can display IGMP
snooping information for dynamically learned and statically configured router
ports and VLAN interfaces. You can also display MAC address multicast entries
for a VLAN configured for IGMP snooping.
Table 5. Commands for
Displaying IGMP Snooping Information
Command
Purpose
show ip igmp snooping [vlanvlan-id [detail] ]
Displays the snooping
configuration information for all VLANs on the
switch or for a specified VLAN.
(Optional) Enter
vlanvlan-id to
display information for a single VLAN. The VLAN ID range is 1 to 1001 and 1006
to 4094.
show ip igmp snooping groups [count | vlanvlan-id]
Displays multicast table
information for the
switch or about a specific parameter:
count—Displays the total number of entries for the
specified command options instead of the actual entries.
vlan-id—The VLAN ID range is 1 to 1001 and 1006 to 4094.
show ip igmp snooping mrouter
[vlanvlan-id]
Displays information on
dynamically learned and manually configured multicast router interfaces.
Note
When you enable IGMP snooping, the
switch automatically learns the interface to
which a multicast router is connected. These are dynamically learned
interfaces.
(Optional) Enter the
vlanvlan-id to
display information for a particular VLAN.
show ip igmp snooping
querier
[vlanvlan-id]
detail
Displays information about
the IP address and receiving port of the most-recently received IGMP query
message in the VLAN and the configuration and operational state of the IGMP
snooping querier in the VLAN.
Monitoring IGMP Filtering
You can display IGMP profile characteristics, and you can display the IGMP profile and maximum group configuration for all
interfaces on the switch or for a specified interface.
Table 6. Commands for Displaying IGMP Filtering
Command
Purpose
show ip igmp profile
[profile
number]
Displays the
specified IGMP profile or all the IGMP profiles defined on the
switch.
show running-config
[interface
interface-id]
Displays the configuration of
the specified interface or the configuration of all interfaces on the
switch, including (if configured) the maximum
number of IGMP groups to which an interface can belong and the IGMP profile
applied to the interface.
Configuration Examples for IGMP Snooping
Example: Enabling a Static Connection to a Multicast Router
This example shows how to enable a static connection to a multicast router:
Example: Configuring
a Host Statically to Join a Group
This example shows how to statically configure a host on a port:
Switch# configure terminalSwitch# ip igmp snooping vlan 105 static 0100.1212.0000 interface gigabitethernet0/1Switch# end
Example: Enabling
IGMP Immediate Leave
This example shows
how to enable IGMP Immediate Leave on VLAN 130:
Switch# configure terminalSwitch(config)# ip igmp snooping vlan 130 immediate-leaveSwitch(config)# end
Example: Setting the
IGMP Snooping Querier Source Address
This example shows
how to set the IGMP snooping querier source address to 10.0.0.64:
Switch# configure terminalSwitch(config)# ip igmp snooping querier 10.0.0.64Switch(config)# end
Example: Setting the
IGMP Snooping Querier Maximum Response Time
This example shows
how to set the IGMP snooping querier maximum response time to 25 seconds:
Switch# configure terminalSwitch(config)# ip igmp snooping querier query-interval 25Switch(config)# end
Example: Setting the
IGMP Snooping Querier Timeout
This example shows
how to set the IGMP snooping querier timeout to 60 seconds:
Switch# configure terminalSwitch(config)# ip igmp snooping querier timeout expiry 60Switch(config)# end
Example: Setting the
IGMP Snooping Querier Feature
This example shows
how to set the IGMP snooping querier feature to Version 2:
Switch# configure terminalSwitch(config)# no ip igmp snooping querier version 2Switch(config)# end
Example: Configuring
IGMP Profiles
This example shows how to
create IGMP profile 4 allowing access to the single IP multicast address and
how to verify the configuration. If the action was to deny (the default), it
would not appear in the
show ip igmp profile
output display.
Switch(config)# ip igmp profile 4Switch(config-igmp-profile)# permitSwitch(config-igmp-profile)# range 229.9.9.0Switch(config-igmp-profile)# endSwitch# show ip igmp profile 4
IGMP Profile 4
permit
range 229.9.9.0 229.9.9.0
Example: Applying
IGMP Profile
This example shows how to apply IGMP profile 4 to a port:
Switch(config)# interface gigabitethernet0/2Switch(config-if)# ip igmp filter 4Switch(config-if)# end
Example: Setting the
Maximum Number of IGMP Groups
This example shows how to limit to 25 the number of IGMP groups that a port can join:
Switch(config)# interface gigabitethernet0/2Switch(config-if)# ip igmp max-groups 25Switch(config-if)# end
Additional
References
Related
Documents
Related
Topic
Document
Title
For
complete syntax and usage information for the commands used in this chapter.
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