IGMP

IGMP(Internet Group Management Protocol) is a communication protocol used to managed the membership of the Internet Protocol multicast group.It is used by the Hosts and adjacent multicast routers to established multicast group membership.
IGMP has three versions IGMP v1, v2 and v3.

> IGMPv1: Hosts can join multicast groups. There were no leave messages. Routers were using a time-out based mechanism to discover the groups that are of no interest to the members.It send only member specific query.

> IGMPv2: Leave messages were added to the protocol. Allow group membership termination to be quickly reported to the routing protocol, which is important for high-bandwidth multicast groups and/or subnets with highly volatile group membership.It send group specific query.

> IGMPv3: Major revision of the protocol. It allows hosts to specify the list of hosts from which they want to receive traffic from. Traffic from other hosts is blocked inside the network. It also allows hosts to block inside the network packets that come from sources that sent unwanted traffic. It send group as well as source specific query

The variant protocols of IGMP are:

• DVMRP: Distance Vector Multicast Routing Protocol.
• IGAP: IGMP for user Authentication Protocol.
• RGMP: Router-port Group Management Protocol.

There are basically 5 types of messages in the IGMP that must be implemented in IGMP for the IGMP v3 functional properly and be compatible with previous versions:

• 0x11: membership query
• 0x22: version 3 membership report
• 0x12: version 1 membership report
• 0x16: version 2 membership report
• 0x17 version 2 leave group

IGMP Snooping : It is the method which provide intelligence to gateway or router to avoid the multicast flooding on the device.

SSM(Source Specific Multicast) : It is method to deliver multicast packets, in which the packets that are delivered to a reciver are those packets which originating from a specific source address requested by the reciver . So limiting the source ,SSM reduce the demands on the network and improve the security.

Now these day there is boom for the IPTV, IGMP protocol is very important protocol for the IPTV functionality.IGMPv2 and V3 can be used for the IPTV.
In my next blog i will going to explain what are the roles of IGMP in the IPTV.

Note: For doing the testing of the IGMP basic functionality we can use the some open source tools .

Examples:

1) Iperf:
It is a commonly used network testing tool that can Create the TCP and UDP streams and measure the throughput of a network that is carrying them .

On LAN Side of DUT: iperf -s -B 239.193.244.160 -p 5555 -u
On WAN Side of DUT : iperf -c 239.193.244.160 -p 5555 -u -T 12
Note: Jperf is a graphical froentend for iperf.
2) VLC Player.
On WAN side of the DUT stream the media using the VLC player and from the LAN side play the stream media.

3) Piref :
It is the tool to create the IGMPv3 packets for include and exclude functionality, it is used to do the performance or load testing of the IGMP .