[Yandex Cloud documentation](../../index.md) > [Yandex BareMetal](../index.md) > [Concepts](index.md) > Network > MC-LAG

# Reserving a BareMetal network connection using MC-LAG

For critical tasks that require high fault tolerance of physical network infrastructure, Yandex BareMetal provides a solution for reserving a network connection using [MC-LAG](https://en.wikipedia.org/wiki/Multi-chassis_link_aggregation_group).

MC-LAG (multi-chassis link aggregation group) is a type of link aggregation groups that reserve a connection to [network switches](https://en.wikipedia.org/wiki/Network_switch). The MC-LAG technology is supported by BareMetal server [configurations](server-configurations.md) with two [network interfaces](servers.md#network-interfaces) hooked up to each of the networks ([public](public-network.md) and [private](private-network.md)).

In each network, the MC-LAG servers use two independent network ports of two different network adapters to connect to two different switches forming an MC-LAG pair at the same time. If one of the network adapters or switches fails, the second active connection ensures network connectivity of the server and provides fault tolerance.

## Configuring aggregation groups and network interfaces {#additional-setup}

Servers with MC-LAG support are simultaneously connected to each of the networks using two network adapters. Each adapter, in turn, is connected to a separate network switch over LACP 802.3ad. Network interface pairs connected to the networks form _aggregation groups_ on the server side.

When you install the server OS with MC-LAG support from a public [Marketplace image](images.md#marketplace-images), aggregation groups are configured automatically during the OS installation, no manual setup required.

When you install the OS from a [custom image](images.md#user-images), server network interfaces will not form aggregation groups, and only one of the two interfaces connected to each of the networks (public and private) will be active. You will need to [configure](../operations/servers/set-up-mc-lag.md) aggregation groups manually. When configuring aggregation groups, you must disable [DHCP](dhcp.md) for the network interfaces and enable it for the aggregation groups.

To learn more about configuring MC-LAG on the server side, see [Configuring the MC-LAG aggregation group](../operations/servers/set-up-mc-lag.md).

#### See also {#see-also}

* [Network](network.md)
* [Public network](public-network.md)
* [Private network](private-network.md)
* [DHCP in a Yandex BareMetal network](dhcp.md)
* [Restrictions in BareMetal networks](network-restrictions.md)
* [OS images](images.md)
* [Configuring the MC-LAG aggregation group](../operations/servers/set-up-mc-lag.md)