A number of platforms on the Internet use the multicast method to transfer data to a group of users. This technology is used for online games, live broadcasts, distance learning, and even for mailing lists. But multicasting does not always intelligently optimize traffic relay and loads the user’s network, therefore, to eliminate this problem, the IGMP snooping function was created. Let’s figure out what this function is and how to enable it to optimize its traffic.
First, let’s define IGMP to understand how the technology works. Internet Group Management Protocol – A multicast network management protocol that organizes multiple devices into groups. It is based on the IP protocol and is used on the Internet everywhere, effectively using network resources.
IGMP snooping is the process of tracking multicast traffic between a consumer group and a host. The included snooping function begins to analyze the user’s requests for connection to the multicast group and adds the port to the IGMP broadcast list. After completing the use of multitraffic, the user leaves a request and protocol, removes the port from the list of multicast data transfer.
Thus snooping eliminates the transmission of unnecessary data to the user through multicast channels. This makes data exchange at the data link layer of the network more efficient and takes into account the needs of the data link layer, which is especially important for information providers. Users will also receive optimized content, although in the end the load on the network will increase.
Without tracking and analyzing data, end users in the form of specific IP addresses will be forced to “digest” additional information that is useless to them. IGMP snooping will not only save users from unnecessary traffic, but also make the exchange of information more secure. When the tracking mode is enabled, it will prevent DDoS attacks on the network or specific addresses to which the Internet Group Management protocol is vulnerable.
Activate IGMP snooping
Traffic tracking and analysis is available on managed network switches or switches. This device helps to implement the principles of group broadcasting at the data link layer of the network. To activate IGMP snooping, you must manually enable and configure it on the switch. Unmanaged counterparts do not support traffic analysis mode, because they cannot be configured through the interface.
Before using the device on your network, make sure that the final recipient (for example, smart-tv) supports snooping mode. Typically, devices have a corresponding item in the “Configuring a network connection” section, which greatly simplifies the adjustment of multicast.
Consider the method of connecting a function through the command line using the example of the popular D-Link switches:
- Open the device command line using the CLI interface.
- Enter “enable-igmp-snooping”. This command will enable the function on the switch and all connected addresses.
- Enter “config-igmp-snooping-vlan-default-state-enable” to allow the protocol to be configured in VLAN.
- The command “confog-multicast-vlan-filtering-mode-vlan-default-filter-unregistred-groups” enables the communicator to filter data from several addresses at once.
- Finally, use “config-igmp-snooping-vlan-default-fast-leave-enable” on the VLAN.
The last command includes the IGMP Snooping Fast Leave function, which excludes the port from the network as soon as the user makes a “leave” request. Thanks to Fast Leave, the consumer will not receive unnecessary data and will not process it. This will reduce the load on the network and allow the switch to work more efficiently.
Types of IGMP snooping
Listening and data analysis is divided into two types:
- Passive IGMP snooping . Such a protocol simply tracks data without filtering or analyzing it. In other words, wiretapping works in the background and does not affect the quality of data transfer.
- Active tracking . Not only passively listens for traffic, but also filters it in order to effectively use multicasting on the network. Active IGMP snooping minimizes the exchange of information by filtering requests to the router for connection and disconnection. The ideal state of the switch is the presence of one consumer for each multicast broadcast group, which is what the protocol algorithm strives for.
Snooping with an active algorithm speeds up data transfer and improves network quality, but at the same time creates an additional load on the switch. Filtering requires a certain amount of memory and CPU resources from the device, while simple tracking or relaying is a less demanding procedure. At the same time, active tracking transfers data to the router only about the most recent member of the group so that the device does not determine this as the absence of consumers in the channel and does not exclude the port from the list.
IGMP snooping works well with home networks if you use many IP multicast technologies. By purchasing and configuring a switch with the active tracking function, you will significantly speed up the Internet protocol and protect your home group from hacking and intruders.
