The purpose Internet Group Management Protocol (IGMP) snooping is to restrain multicast traffic in a switched network. By default, a LAN switch floods multicast traffic within the broadcast domain and this can consume a lot of bandwidth if many multicast servers are sending streams to the segment.
Multicast IP addresses are Class D IP addresses. Therefore, all IP addresses from 224.0.0.0 to 239.255.255.255 are multicast IP addresses.
IGMP Snooping can be very effective in network environments where Multicast applications like Video/Audio streaming are being used.
CONFIGURATION - Management IP address and IGMP
1) Plugged the console cable to the Serial port of the switch and the serial port on the PC
2) Open a new Hyper Terminal session (connecting via the COM port) - settings 9600, 8 , None , 1, None
3) Power Cycle the switch
4) Upon POST the User: prompt will appear
5) Username is admin , password "blank"
6) Type Enable to access the privileged mode (password "blank" )
7) Type network protocol none to reset the network settings
8) Type network parms <<Management IP>> <<Subnet Mask>> <<Default Gateway IP>>. For example network parms 192.168.0.2 255.255.255.0 192.168.0.1
9) User copy system:running-config nvram:startup-config to save the configuration
10) Check with show network if the settings are correct
The switch should now be accessible patching a CAT5 Straight-through cable. The PC NIC must be configured with an IP address within the same subnet used to configure the management IP of the switch (Example: 192.168.0.2 255.255.255.0
Enable IGMP Snooping (CLI) on VLAN 1
(GSM7312)# config
(GSM7312) (config) #ip igmpsnooping
(GSM7312) (config) #ip igmpsnooping unknown-multicast filter
(GSM7312) (config) #ip igmpsnooping interfacemode
(GSM7312) (config) #exit
(GSM7312)# vlan database
This command activate IGMP on all the ports in VLAN 1
(GSM7312) (vlan) #ip igmp 1
This command activate the Querier to be the VLAN address (In this case 192.168.0.1)
(GSM7312) (vlan) #ip igmpsnooping querier 1
(GSM7312) (vlan) #exit
Enable IGMP snooping on any VLAN
In order to activate IGMP on any other VLAN the following list of commands must be modified replacing <VLAN-ID> with the VLANID number:
GSM7312)# vlan database
(GSM7312) (vlan) #ip igmp <VLAN-ID>
(GSM7312) (vlan) #ip igmpsnooping querier <VLAN-ID>
(GSM7312) (vlan) #exit
Further information can be found here.
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