What exactly is IGMP, or Internet Group Management Protocol?
A mechanism called the Internet Group Management Protocol (IGMP) enables several devices to share a single IP address so they may all access the same data. On networks using Internet Protocol version 4, multicasting is set up using the network layer protocol IGMP (IPv4). The IGMP protocol specifically enables devices to join a multicasting group.
When many devices receive the same messages or packets, this is known as multicasting. Sharing an IP address across several devices is how multicasting operates. Instead of just one device, any network communication addressed at that IP address will reach all devices that share the IP address. This is comparable to the situation where several workers get business emails addressed to a certain email alias.
How does IGMP function?
When they wish to join a multicast group, computers and other networked devices use IGMP. The devices that are a part of each multicast group are identified by the router that implements IGMP by listening to their IGMP messages.
IP addresses designated for multicasting are used by IGMP. The range of multicast IP addresses is 126.96.36.199 to 188.8.131.52. (Anycast networks, by contrast, allow the use of any standard IP address.) One of these IP addresses is shared by each multicast group. A router will make copies of each packet it receives that is destined for the shared IP address and transmit them to each member of the multicast group.
IGMP multicast groups are dynamic and subject to modification. An IGMP “join group” or “leave group” message can be sent at any time by a device.
Directly built upon Internet Protocol, IGMP (IP). Both header and an IP header are present in every IGMP packet. It does not utilise a transport layer protocol like TCP or UDP, much like ICMP does not.
What varieties of IGMP messages exist?
Multiple IGMP message types are supported by the IGMP protocol:
- Devices communicate these to a multicast router in order to join a multicast group. Membership reports
- These messages, which are sent from a device to a router and enable devices to leave a multicast group, are known as “leave group” messages.
- Basic membership questions: To update multicast group membership for all groups on the network, a multicast-capable router broadcasts these messages to every connected device in the network.
- Membership inquiries for certain groups: Instead of sending these messages to the whole network, routers transmit them to a specified multicast group.
What does IGMP spying entail?
Only networking devices that are aware of the network layer may send and receive messages using the IGMP protocol, which is a network layer protocol. A network switch may only be aware of layer 2, often known as the data link layer, whereas a router functions at the network layer. A switch might not be aware of which network devices are included in multicast groups and which are not as a result. Multicast traffic may wind up being sent to devices that don’t require it, using up network bandwidth and draining device computing power while slowing down the overall network.
By allowing switches to “snoop” on it messages, IGMP snooping provides a solution to this problem. Layer 2 switches aren’t typically aware of IGMP messages, but they can listen in by using IGMP snooping. They may then determine which devices should receive multicast traffic by determining where multicast messages should be delivered.
How do IPv4 and IPv6 multicasting vary from one another?
There are two versions of the Internet Protocol: IPv4 and IPv6 (IP). Although IPv6 is more recent, IPv4 is still widely used. The multicasting protocol in IPv6 is Multicast Listener Discovery (MLD), not IGMP.
What distinguishes multicasting from anycast and unicast?
Anycast versus multicast
Another technology that makes it possible for network messages to reach several locations is anycast. An anycast network allows the same group of servers to share one or more IP addresses, much as a multicast network. However, the network sends traffic to one of those servers depending on a preset set of criteria rather than all servers getting all traffic to those IP addresses. In comparison to multicast groups, anycast networks may accommodate a larger variety of IP addresses. The Cloudflare network, as an illustration, employs anycast to direct all user traffic to the nearby data centre.
Unicast versus multicast
The majority of the Internet operates in a “unicast” fashion. Each connected device has a different address in unicast networks. In contrast to multicasting, messages sent to that address (on the Internet, an IP address) only reach that one device.