IGMP Configuration
The following example shows IGMP configuration on Router1.
Configuring IGMP Version
The configuration that follows shows how IGMP version can be configured.
#configure terminal | Enter configure mode. |
(config)#ip multicast-routing | Enable IP multicast routing |
(config)#interface eth2 | Enter interface mode. |
(config-if)#ip address 10.1.1.10/24 | Assign IP address to an interface |
(config-if)#ip igmp version 2 | Enable IGMP version as v2. |
(config-if)#exit | Exit interface mode. |
(config)#exit | Exit Configure mode. |
Validation
Enter the commands listed in this section to confirm the previous configurations.
#show running-config
!
no service password-encryption
!
hostname rtr1
!
ip multicast-routing
!
!
interface eth2
ip address 10.1.1.10/24
no shutdown
ip igmp version 2
Configuring IGMP Parameters
The configuration that follows shows how IGMP parameters can be configured.
#configure terminal | Enter configure mode. |
(config)#ip multicast-routing | Enable IP multicast routing |
(config)#interface eth2 | Enter interface mode |
(config-if)#ip igmp access-group 1 | Configures a access-list policy to control the multicast groups that hosts on the subnet serviced by an interface can join. |
(config-if)#ip igmp immediate-leave group-list 1 | Enables the device to remove the group entry from the multicast routing table immediately upon receiving a leave message for the group. |
(config-if#ip igmp join-group 224.1.1.1 | Statically binds a multicast group to the outgoing interface |
(config-if)#ip igmp last-member-query-count 7 | Sets the query count used when the software starts up. |
(config-if)#ip igmp last-member-query-interval 25500 | Sets the query interval used when the software starts up. |
(config-if)#ip igmp limit 100 | Configure Max Allowed State on this interface |
(config-if)#ip igmp querier-timeout 300 | Sets the querier timeout that the router uses when deciding to take over as the querier. |
(config-if)#ip igmp query-interval 200 | Sets the frequency at which the router sends IGMP host query messages. |
(config-if)#ip igmp query-max-response-time 150 | Sets the response time advertised in IGMP queries. |
(config-if)#ip igmp ra-option | Enable ra-option. |
(config-if)#ip igmp robustness-variable 4 | Sets the robustness variable. |
(config-if)#ip igmp startup-query-count 4 | Sets the query count used when the router starts up. |
(config-if)#ip igmp startup-query-interval 50 | Sets the query interval used when the router starts up. |
(config-if)#ip igmp static-group 225.1.1.1 | Statically binds a multicast group to the outgoing interface. |
(config-if)#exit | Exit interface mode. |
(config)#exit | Exit Configure mode. |
Validation
Enter the commands listed in this section to confirm the previous configurations.
Rtr1#show running-config
!
no service password-encryption
!
hostname rtr1
!
!
ip multicast-routing
!
!
interface eth2
ip address 10.1.1.10/24
no shutdown
ip igmp access-group 1
ip igmp immediate-leave group-list 1
ip igmp last-member-query-count 7
ip igmp limit 100
ip igmp join-group 224.1.1.1
ip igmp static-group 225.1.1.1
ip igmp last-member-query-interval 25500
ip igmp querier-timeout 300
ip igmp query-interval 200
ip igmp query-max-response-time 150
ip igmp startup-query-interval 50
ip igmp startup-query-count 4
ip igmp robustness-variable 4
ip igmp ra-option
ip igmp version 2
!!
Rtr1#show ip igmp interface eth2
Interface eth2 (Index 4)
IGMP Enabled, Active, Querier, Configured for version 2
Internet address is 10.1.1.10
IGMP interface limit is 100
IGMP interface has 2 group-record states
IGMP Interface statistics:
v1-reports: 0
v2-reports: 0, v2-leaves: 0
v3-reports: 0
IGMP query interval is 200 seconds
IGMP Startup query interval is 50 seconds
IGMP Startup query count is 4
IGMP querier timeout is 300 seconds
IGMP max query response time is 150 seconds
Group Membership interval is 950 seconds
IGMP Last member query count is 7
Last member query response interval is 25500 milliseconds
Here is the sample configuration on Router-1 with all the IGMP related commands configured.
Rtr1#show running-config
!
no service password-encryption
!
hostname rtr1
!
!
ip domain-lookup
!
ip multicast-routing
!
ip pim register-rp-reachability
ip pim crp-cisco-prefix
!
interface lo
ip address 127.0.0.1/8
ip address 1.1.1.57/32 secondary
ipv6 address ::1/128
no shutdown
!
interface eth0
ip address 10.12.48.179/24
no shutdown
!
interface eth1
ip address 192.168.1.27/24
no shutdown
ip igmp version 2
!
interface eth2
ip address 10.1.1.10/24
no shutdown
ip igmp access-group 1
ip igmp immediate-leave group-list 1
ip igmp last-member-query-count 7
ip igmp limit 100
ip igmp join-group 224.1.1.1
ip igmp static-group 225.1.1.1
ip igmp last-member-query-interval 25500
ip igmp querier-timeout 300
ip igmp query-interval 200
ip igmp query-max-response-time 150
ip igmp startup-query-interval 50
ip igmp startup-query-count 4
ip igmp robustness-variable 4
ip igmp ra-option
ip igmp version 2
!
line con 0
login
line vty 0 16
exec-timeout 0 0
login
line vty 17 39
login
!
End
IGMP Group Table after IGMPV2 Membership Report is received
IGMP group table is populated at router by virtue of either static join is configured on interface or dynamic report is being received on the interface.
The show ip igmp group command displays the IGMP group table. In this table, the following fields are defined.
Table 1: IGMP group table after IGMPV2 membership report
Group address | Displays the Multicast Group for which report is received. |
Interface | Interface name on which Membership report is received. |
Uptime | Duration since the report is received. |
Expiry | Time frame in which the multicast group is going to expire. |
Last Reporter | Host address from where the report is generated. |
Rtr1#show ip igmp groups
IGMP Connected Group Membership
Group Address Interface Uptime Expires Last Reporter
224.0.1.3 eth2 00:10:06 00:03:43 10.1.1.52
224.1.1.1 eth2 01:54:53 static 0.0.0.0
225.1.1.1 eth2 00:17:22 static 0.0.0.0
Rtr1#show ip igmp groups detail
IGMP Connected Group Membership Details
Flags: (M - SSM Mapping, R - Remote, L - Local,
SG - Static Group, SS - Static Source)
Interface: eth2
Group: 224.0.1.3
Flags: R
Uptime: 00:10:06
Group mode: Exclude (Expires: 00:03:43)
State: Active
Last reporter: 10.1.1.52
Source list is empty
Flags: (M - SSM Mapping, R - Remote, L - Local,
SG - Static Group, SS - Static Source)
Interface: eth2
Group: 224.1.1.1
Flags: L
Uptime: 01:54:59
Group mode: Exclude (Static)
State: Active
Last reporter: 0.0.0.0
Source list is empty
Flags: (M - SSM Mapping, R - Remote, L - Local,
SG - Static Group, SS - Static Source)
Interface: eth2
Group: 225.1.1.1
Flags: SG
Uptime: 00:17:28
Group mode: Exclude (Static)
State: Active
Last reporter: 0.0.0.0
Source list is empty
IGMP Group Table after IGMPV3 Membership report is received
IGMP group table is populated at router by virtue of either static join is configured on interface or dynamic report is being received on the interface. Here IGMPV3 should be configured on the interface (by default IGMPv3 will be enabled if pim is configured on the interface).
The show ip igmp group command displays the IGMP group table. In this table, the following fields are defined.
Table 2: IGMP group table after IGMPV3 membership
Group address | Displays the Multicast Group for which report is received. |
Interface | Interface name on which Membership report is received. |
Uptime | Duration since the report is received. |
Expiry | Time frame in which the multicast group is going to expire. |
Last Reporter | Host address from where the report is generated. |
rtr6#show ip igmp groups
IGMP Connected Group Membership
Group Address Interface Uptime Expires Last Reporter
224.0.1.3 eth2 00:08:50 00:02:10 192.168.10.52
rtr6#show ip igmp groups detail
IGMP Connected Group Membership Details
Flags: (M - SSM Mapping, R - Remote, L - Local,
SG - Static Group, SS - Static Source)
Interface: eth2
Group: 224.0.1.3
Flags: R
Uptime: 00:08:50
Group mode: Exclude (Expires: 00:04:57)
Last reporter: 192.168.10.52
Group source list: (R - Remote, M - SSM Mapping, S - Static, L - Local)
Exclude Source List :
Source Address Uptime v3 Exp Fwd Flags
1.2.3.4 00:08:50 stopped No R
For IGMPV3 report source list specifies which source to be included or exclude based on the membership report sent by the hosts.
In the above show command, Source address 1.2.3.4 is excluded to send Multicast data for group 224.0.1.3