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MC-LAG redundant connection

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MC-LAG (Multi-chassis link aggregation group) - Multi-chassis link aggregation. MC-LAG (Multi-chassis link aggregation group) is a multi-chassis link aggregation group. It reserves the connection to LAN and Internet access switches and increases the fault tolerance of the infrastructure. Only LAN connectivity can be reserved for off-the-shelf configuration servers. Redundancy is not available for all configurations.

MC-LAG can be configured can only be configured for servers that have a redundant NIC and MC-LAG in their configuration.

For servers with redundant MC-LAG connectivity, Selectel ensures that one of the access switches is always available, including during scheduled maintenance.

Principle of operation

The server is connected to two independent switches via a LAG (Link Aggregated Ethernet Channel). LACP 802.3ad protocol is used for connection and channel aggregation is configured on the server side. In this case, two links from the access switches to the server will be active simultaneously.

Connection speed

For servers of custom configuration:

  • 1 Gbps - copper crossing is used for the connection;
  • 10 Gbps - optical crossing is used for the connection;
  • 25 Gbps - for LAN only, optical crossover is used for connection.

For off-the-shelf configuration servers:

  • 10 Gbit/s - for public network, optical crossover is used for connection;
  • 10 Gbit/s - for local network, optical crossover is used for connection;
  • 25 Gbit/s - for local network, optical crossover is used for connection.

Cost

The cost of the MC-LAG redundant connection depends on the selected connection speed.

You can view the cost in the configurator on the site, or when selecting server components in the control panel.

Customize MC-LAG

  1. Make sure that the dedicated server configuration has a redundant NIC and MC-LAG added. If there is no redundant NIC, you can order a new redundant server or modify the components for a randomly configured server.
  2. Wait for the server readiness message from technical support. The switch ports will be bonded together.
  3. Configure link aggregation (LAG) on the server.

Configure channel aggregation on the server

Do not connect to the server on network interfaces that will be included in the aggregation. You will need to disconnect them during configuration.

  1. Connect to the server on a network interface that will not be included in the aggregation, or through a KVM console.

  2. Output information about the network interfaces:

    ip link

  3. Open the /etc/netplan/01-netcfg.yaml file:

    nano /etc/netplan/01-netcfg.yaml

  4. Bring the settings for the network interfaces that will be included in the aggregation to the following:

    network:
      version: 2
      renderer: networkd
      ethernets:
        <eth_name_1>:
          dhcp4: false
        <eth_name_2>:
          dhcp4: false

      bonds:
        bond0:
          addresses:
            - <ip_address>/<mask>
          gateway4: <gateway_4>
          gateway6: <gateway_6>
          interfaces:
            - <eth_name_1>
            - <eth_name_2>
          # https://netplan.io/reference#properties-for-device-type-bonds
          parameters:
            mode: 802.3ad
            lacp-rate: fast
            transmit-hash-policy: layer3+4
            mii-monitor-interval: 100
            down-delay: 100
            up-delay: 100

    Specify:

    • <eth_name_1>, <eth_name_2> - the names of the network interfaces that are included in the aggregation;
    • <ip_address> - The IP address to use on the aggregated interface;
    • <mask> - subnet mask;
    • <gateway_4>, <gateway_6> - gateway.

  5. Apply the new configuration:

    netplan --debug apply

  6. Verify that the bond0 network interface is assembled correctly:

    cat /proc/net/bonding/bond0