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 forwarding and loads the user's network, so the IGMP snooping function was created to eliminate this problem. Let us understand what this function is and how to enable it to optimize your traffic.
What is IGMP snooping and why?
To begin with, we will define IGMP to understand how technology works. Internet Group Management Protocol is a multicast network management protocol that organizes several devices into groups. It is based on the IP protocol and is used throughout the Internet, effectively using network resources.
IGMP snooping is the process of tracking multicast traffic between a consumer group and a host. The included snooping function starts analyzing user requests for a connection to a multicast group and adds the port to the IGMP broadcast list. After completing the use of multi-traffic, the user leaves the request and protocol, removes the port from the list of multicast data.
Thus, snooping eliminates the transfer of unnecessary data to the user through multicast channels. This makes data exchange at the data link layer more efficient and takes into account the needs of the network layer, which is especially important for information providers. Users will also receive optimized content, although as a result 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 for them. IGMP snooping will not only save users from unnecessary traffic, but also make information sharing more secure. Turning on the tracking mode in time will prevent attempts of DDoS attacks on the network or specific addresses to which the Internet Group Management protocol is vulnerable.
Activating IGMP snooping
Tracking and traffic analysis is available on managed network switches or switches. This device helps to implement the principles of multicast on the data link layer network. To activate IGMP snooping, you must manually enable and configure it on the switch. Unmanaged analogues do not support the traffic analysis mode, since 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. Typically, devices have the appropriate item in the section "Setting up a network connection", which makes it much easier to adjust multicasting.
Consider the way to connect the function via the command line using the example of popular D-Link switches:
- Open the device command line using the CLI interface.
- Enter "enable-igmp-snooping". This command will enable the feature on the switch and all connected addresses.
- Enter "config-igmp-snooping-vlan-default-state-enable" to configure the protocol in the VLAN.
- The "confog-multicast-vlan-filtering-mode-vlan-default-filter-unregistred-groups" command enables the device to filter data from several addresses at once.
- Finally, use "config-igmp-snooping-vlan-default-fast-leave-enable" in the VLAN.
The last command includes the IGMP Snooping Fast Leave feature, 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 them. This will reduce the network load and allow the switch to work more efficiently.
Types of IGMP snooping
Wiretapping 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, the wiretap works in the background and does not affect the quality of data transfer.
- Active tracking. Not only passively listens to traffic, but also filters it in order to efficiently use multicasting in the network. Active IGMP snooping minimizes the exchange of information, eliminating requests to the router to connect and disconnect. The ideal state of the switch is the presence of one consumer for each multicast group of broadcasting, to which the protocol algorithm tends.
Snooping with an active algorithm speeds up the transfer of data and improves the quality of the network, but it also 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 only transfers data to the router about the most recent member of the group, so that the device does not detect this as the absence of consumers in the channel and does not exclude the port from the list.
IGMP snooping works great with home networks if you use a lot of IP multicast technologies. By purchasing and configuring a switch with the active tracking function, you will significantly speed up the work of the Internet protocol and protect the home team from hacking and intruders.
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