Home > Tech Gallery > What is IGMP and How Does it Work for Multicast Communication?
Time: November 22nd, 2023
What is IGPM
and what are its basic operations? We will discuss all that in this article in detail.
Multicast
communication is a method of transmitting data to devices simultaneously using an
IP
address. This can be beneficial, for applications like streaming, gaming, or web conferencing that require
low latency
. However, it's important to consider that not all devices on a network may want to receive the data. Sending data to devices can lead to a waste of network resources and congestion issues. To address this concern devices, need a mechanism to indicate their interest in joining or leaving a group. This is where
IGMP
comes into play.
What is
IGMP
?
IGMP
stands for
Internet Group Management Protocol
. It's a protocol designed for hosts. Routers on IPv4 networks to establish and manage group memberships. IGMP plays a role in
IP
multicast
by ensuring that multicast transmissions are directed towards hosts that have requested them.
IGMP
operates at
the network layer
above the
IP
protocol without utilizing
transport layer
protocols like TCP or
UDP
. Each IGMP message consists of an IGMP header and an IP header. The IGMP header contains information such as the type of message the
multicast
group address and the
checksum
. The IP header includes details, like source and destination IP addresses protocol number, and time to live.
How does
IGMP
function?
IGMP
operates through the exchange of messages, between hosts and routers within a network. There are three types of IGMP messages;
1. Membership reports:
Hosts send these messages to routers to join or confirm their membership in a group. A host will send a membership report when it desires to receive data from a group or in response to a
router
's
query
. The membership report includes the
multicast
group address that the host wishes to join or confirm.
2. Queries:
Routers send these messages to hosts to discover or verify the membership of a group. A router will initiate a
query
when it wants to determine which hosts on its network are interested in receiving data from a group or if it wants to update its knowledge regarding existing memberships. A query can be either general requesting information, about all groups, or specific focusing on the membership of a
multicast
group. The query contains the multicast group address that the router wishes to inquire about or zero for queries.
3. Leave messages:
Hosts employ these messages to inform routers that they wish to leave a group.
When a host decides it no longer wants to receive data from a group it sends a leave message that includes the
multicast
group address it wishes to leave.
What are the basic operations of
IGMP
?
The basic operation of
IGMP
can be summarized as follows;
1. When a host wants to join a group, it notifies the router by sending a membership report. The router updates its
multicast
routing table. If necessary, forward the membership report to routers.
2. When a router needs information about the membership of a group it sends out queries to the hosts. The hosts that are part of the group respond with membership reports. The
router
updates its
multicast
routing table. If necessary, forward the queries to routers.
3. If a host intends to exit or leave a group it sends a leave message to the
router
. The router updates its
multicast
routing table. If necessary, forward this message to routers.
In conclusion
What is IGPM
?
IGMP
is an IPv4
network protocol
that facilitates communication for multicasting. It enables hosts and routers to exchange messages to establish and manage memberships within groups. By ensuring that only interested hosts receive the data IGMP enhances efficiency and reliability in transmission.
IGMP
comes in three versions, with varying features and capabilities. IGMP is commonly utilized in applications that necessitate fast data transmission and minimal delay such as streaming media, online gaming, or web-based video conferences. We have discussed what is IGMP, how it functions, and what are its basic functions in this article in detail. Hope you have gained some useful information about this topic which will be helpful to you in the future.
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