How to manage machine interfaces (snap/3.1/CLI)

This article will explain the following procedures related to machine interfaces:

How to edit machines interfaces

From a machine’s “Interfaces” page, click the menu icon for the interface to be edited and select “Edit Physical” from the resulting menu:

The following window will appear:

Four modes determine how a subnet address is assigned when MAAS deploys the machine. You can select one of these modes by clicking on the “IP mode” drop-down menu.

  • Auto assign: MAAS will assign a random static address (iface eth0 inet static). The pool of available addresses depends on whether the subnet is managed or unmanaged (see Subnet management).

  • Static assign: The administrator will specify a static address using a secondary field.

  • DHCP: The machine leases a dynamic IP address, via either MAAS-managed DHCP or an external DHCP server.

  • Unconfigured: The interface is not configured.

Press the “Save” button to apply the changes.

If you want to edit the IP assignment mode of a network interface, the existing subnet link first needs to be removed.

Begin by finding the interface ID as well as the interface’s subnet link ID with the command:

maas $PROFILE node read $SYSTEM_ID

Once that’s done, proceed to unlink and link:

maas $PROFILE interface unlink-subnet $SYSTEM_ID $INTERFACE_ID id=$SUBNET_LINK_ID
maas $PROFILE interface link-subnet $SYSTEM_ID $INTERFACE_ID mode=$IP_MODE subnet=$SUBNET_CIDR [$OPTIONS]

For instance, to have interface 58, with subnet link 146, on machine exqn37 use DHCP on subnet 192.168.1.0/24:

maas $PROFILE interface unlink-subnet exqn37 58 id=146
maas $PROFILE interface link-subnet exqn37 58 mode=dhcp subnet=192.168.1.0/24

If instead of DHCP, you desire a static address, then the second command would look like this:

maas $PROFILE interface link-subnet exqn37 58 mode=static subnet=192.168.1.0/24 ip_address=192.168.1.113

See Concepts and terms for the definitions of reserved range types.

How to create a bond interface

A bond is created by selecting more than one interface and clicking the now-active “Create bond” button:

After clicking the “Create bond” button, the bond configuration pane will appear.

From the bond configuration pane, you can rename the bond, select a bond mode (see below), assign a MAC address to the aggregate device and attach one or more tags.

The interfaces aggregated into the bond interface are listed below the “Tags” field. Use the “Primary” column to select the interface to act as the primary device.

You can select from the following bonding modes on the “Bond mode” drop-down menu:

  • balance-rr: Transmit packets in sequential order from the first available slave through to the last. This mode provides load balancing and fault tolerance.

  • active-backup: Only one slave in the bond is active. A different slave becomes active if, and only if, the active slave fails. The bond’s MAC address is externally visible on only one port (network adaptor) to avoid confusing the switch.

  • balance-xor: Transmit based on the selected transmit hash policy. The default policy is simple, which means that an XOR operation selects packages. This XOR compares the source MAC address and the resultant XOR between the destination MAC address, the packet type identifier, and the modulo slave count.

  • broadcast: Transmit everything on all slave interfaces. This mode provides fault tolerance.

  • 802.3ad: Creates aggregation groups that share the same speed and duplex settings. This mode utilises all slaves in the active aggregation, following the IEEE 802.3ad specification.

  • balance-tlb: Adaptive transmit load balancing, channel bonding that does not require any special switch support.

  • balance-alb: Adaptive load balancing, includes balance-tlb plus receive load balancing (rlb) for IPV4 traffic. This mode does not require any special switch support. ARP negotiation achieves load balancing in this case.

Press the “Save” button when you’re done.

The MAC address defaults to the MAC address of the primary interface.

A bond can be created with the following command:

maas $PROFILE interfaces create-bond $SYSTEM_ID name=$BOND_NAME \
parents=$IFACE1_ID mac_address=$MAC_ADDR \ 
parents=$IFACE2_ID bond_mode=$BOND_MODE \
bond_updelay=$BOND_UP bond_downdelay=$BOND_DOWN mtu=$MTU

Use the parents parameters to define which interfaces form the aggregate interface.

The bond_updelay and bond_downdelay parameters specify the number of milliseconds to wait before either enabling or disabling a slave after a failure has been detected.

The following is an example of create-bond in action:

maas admin interfaces create-bond 4efwb4 name=bond0 parents=4 \
mac_address=52:52:00:00:00:00 parents=15 bond_mode=802.3ad \
bond_updelay=200 bond_downdelay=200 mtu=9000

There are a wide range of bond parameters you can choose when creating a bond:

Parameter Type and description
mac_address Optional string. MAC address of the interface.
tags Optional string. Tags for the interface.
vlan Optional string. VLAN the interface is connected to. If not provided then the interface is considered disconnected.
parents Required integer. Parent interface ids that make this bond.
bond_miimon Optional integer. The link monitoring frequency in milliseconds. (Default: 100).
bond_downdelay Optional integer. Specifies the time, in milliseconds, to wait before disabling a slave after a link failure has been detected.
bond_updelay Optional integer. Specifies the time, in milliseconds, to wait before enabling a slave after a link recovery has been detected.
bond_lacp_rate Optional string. Option specifying the rate at which to ask the link partner to transmit LACPDU packets in 802.3ad mode. Available options are fast or slow. (Default: slow).
bond_xmit_hash_policy Optional string. The transmit hash policy to use for slave selection in balance-xor, 802.3ad, and tlb modes. Possible values are: layer2, layer2+3, layer3+4, encap2+3, encap3+4. (Default: layer2)
bond_num_grat_arp Optional integer. The number of peer notifications (IPv4 ARP or IPv6 Neighbour Advertisements) to be issued after a failover. (Default: 1)
mtu Optional integer. Maximum transmission unit.
accept_ra Optional Boolean. Accept router advertisements. (IPv6 only)
autoconf Optional Boolean. Perform stateless autoconfiguration. (IPv6 only)
bond_mode Optional string. The operating mode of the bond. (Default: active-backup).

Supported bonding modes include:

Mode Behaviour
balance-rr: Transmit packets in sequential order from the first available slave through the last. This mode provides load balancing and fault tolerance.
active-backup Only one slave in the bond is active. A different slave becomes active if, and only if, the active slave fails. The bond’s MAC address is externally visible on only one port (network adaptor) to avoid confusing the switch.
balance-xor Transmit based on the selected transmit hash policy. The default policy is a simple [(source MAC address XOR’d with destination MAC address XOR packet type ID) modulo slave count].
broadcast Transmits everything on all slave interfaces. This mode provides fault tolerance.
802.3ad IEEE 802.3ad dynamic link aggregation. Creates aggregation groups that share the same speed and duplex settings. Uses all slaves in the active aggregator according to the 802.3ad specification.
balance-tlb Adaptive transmit load balancing: channel bonding that does not require any special switch support.
balance-alb Adaptive load balancing: includes balance-tlb plus receive load balancing (rlb) for IPV4 traffic, and does not require any special switch support. The receive load balancing is achieved by ARP negotiation.

How to create a bridge interface

Press the “Save” button when you’re done.

Please use the UI interface to create a bridge interface. Select the “UI” dropdown above to see how.

How to delete an interface

An interface can only be deleted via the MAAS CLI. Choose the “CLI” dropdown above to see how.

A bridge interface is created with the following syntax:

maas $PROFILE interfaces create-bridge $SYSTEM_ID name=$BRIDGE_NAME \
parent=$IFACE_ID

Use parent to define the primary interface used for the bridge:

maas admin interfaces create-bridge 4efwb4 name=bridged0 parent=4

The following parameters may be applied when creating a bridge:

  1. name: Optional string. Name of the interface.

  2. mac_address: Optional string. MAC address of the interface.

  3. tags: Optional string. Tags for the interface.

  4. vlan: Optional string. VLAN the interface is connected to.

  5. parent: Optional integer. Parent interface id for this bridge interface.

  6. bridge_type: Optional string. The type of bridge to create. Possible values are: standard, ovs.

  7. bridge_stp: Optional Boolean. Turn spanning tree protocol on or off. (Default: False).

  8. bridge_fd: Optional integer. Set bridge forward delay to time seconds. (Default: 15).

  9. mtu: Optional integer. Maximum transmission unit.

  10. accept_ra: Optional Boolean. Accept router advertisements. (IPv6 only)

  11. autoconf: Optional Boolean. Perform stateless autoconfiguration. (IPv6 only)

The “delete” command can be used to delete a bridge interface, a bond interface or a physical interface:

maas $PROFILE interface delete $SYSTEM_ID $IFACE_ID

For example:

maas admin interface delete 4efwb4 15

The following is output after the successful deletion of an interface:

Success.
Machine-readable output follows:

Note that while the label is presented, there is no machine-readable output expected after the successful execution of the delete command.

How to assign a network interface to a fabric

A network interface may be assigned to a fabric with the MAAS CLI only. Choose the “CLI” dropdown above to see how.

This task is made easier with the aid of the jq utility. It filters the maas command (JSON formatted) output and prints it in the desired way, which allows you to view and compare data quickly. Go ahead and install it:

sudo apt install jq

In summary, MAAS assigns an interface to a fabric by assigning it to a VLAN. First, we need to gather various bits of data.

List some information on all machines:

maas $PROFILE machines read | jq ".[] | \
    {hostname:.hostname, system_id: .system_id, status:.status}" --compact-output

Example output:

{"hostname":"machine1","system_id":"dfgnnd","status":4}
{"hostname":"machine2","system_id":"bkaf6e","status":6}
{"hostname":"machine4","system_id":"63wqky","status":6}
{"hostname":"machine3","system_id":"qwkmar","status":4}

You can only edit an interface when the corresponding machine has a status of ‘Ready’. This state is numerically denoted by the integer ‘4’.

List some information for all interfaces on the machine in question (identified by its system id ‘dfgnnd’):

maas $PROFILE interfaces read dfgnnd | jq ".[] | \
    {id:.id, name:.name, mac:.mac_address, vid:.vlan.vid, fabric:.vlan.fabric}" --compact-output

Example output:

{"id":8,"name":"eth0","mac":"52:54:00:01:01:01","vid":0,"fabric":"fabric-1"}
{"id":9,"name":"eth1","mac":"52:54:00:01:01:02","vid":null,"fabric":null}

List some information for all fabrics:

maas $PROFILE fabrics read | jq ".[] | \
    {name:.name, vlans:.vlans[] | {id:.id, vid:.vid}}" --compact-output

Example output:

{"name":"fabric-0","vlans":{"id":5001,"vid":0}}
{"name":"fabric-1","vlans":{"id":5002,"vid":0}}
{"name":"fabric-2","vlans":{"id":5003,"vid":0}}

This example will show how to move interface ‘8’ (on machine ‘dfgnnd’) from ‘fabric-1’ to ‘fabric-0’. Based on the gathered information, this will consist of changing the interface’s VLAN from ‘5002’ to ‘5001’:

maas $PROFILE interface update dfgnnd 8 vlan=5001 >/dev/null

Verify the operation by relisting information for the machine’s interface:

maas $PROFILE interfaces read dfgnnd | jq ".[] | \
    {id:.id, name:.name, mac:.mac_address, vid:.vlan.vid, fabric:.vlan.fabric}" --compact-output

The output shows that the interface is now on fabric-0:

{"id":8,"name":"eth0","mac":"52:54:00:01:01:01","vid":0,"fabric":"fabric-0"}
{"id":9,"name":"eth1","mac":"52:54:00:01:01:02","vid":null,"fabric":null}

How to discover interface identifiers

Interface identifiers can only be discovered via the MAAS CLI. Choose the “CLI” dropdown above to see how.

The MAAS CLI uses a numeric interface identifier for many interface operations. Use the following command to retrieve the identifier(s):

maas $PROFILE interfaces read $SYSTEM_ID

Look for either id or the number at the end of an interface’s resource URI, such as 15 in the following example output:

"id": 15,
"mac_address": "52:54:00:55:06:40",
...
"name": "ens9",
...
"resource_uri": "/MAAS/api/2.0/nodes/4efwb4/interfaces/15/"

How to create a VLAN interface

VLAN interfaces can only be created via the MAAS CLI. Select the “CLI” dropdown above to see how.

To create a VLAN interface, use the following syntax:

maas $PROFILE vlans create $FABRIC_ID name=$NAME vid=$VLAN_ID

For example, the following command creates a VLAN called 'Storage network:

maas admin vlans create 0 name="Storage network" vid=100

The above command generates the following output:

Success.
Machine-readable output follows:
{
    "vid": 100,
    "mtu": 1500,
    "dhcp_on": false,
    "external_dhcp": null,
    "relay_vlan": null,
    "name": "Storage network",
    "space": "undefined",
    "fabric": "fabric-0",
    "id": 5004,
    "primary_rack": null,
    "fabric_id": 0,
    "secondary_rack": null,
    "resource_uri": "/MAAS/api/2.0/vlans/5004/"
}

Be aware that the $VLAN_ID parameter does not indicate a VLAN ID that corresponds to the VLAN tag. You must first create the VLAN and then associate it with the interface:

maas $PROFILE interfaces create-vlan $SYSTEM_ID vlan=$OUTPUT_VLAN_ID \
parent=$IFACE_ID

OUTPUT_VLAN_ID corresponds to the id value output when MAAS created the VLAN.

The following example contains values that correspond to the output above:

maas admin interfaces create-vlan 4efwb4 vlan=5004 parent=4

The above command generates the following output:

Success.
Machine-readable output follows:
{
    "tags": [],
    "type": "vlan",
    "enabled": true,
    "system_id": "4efwb4",
    "id": 21,
    "children": [],
    "mac_address": "52:54:00:eb:f2:29",
    "params": {},
    "vlan": {
        "vid": 100,
        "mtu": 1500,
        "dhcp_on": false,
        "external_dhcp": null,
        "relay_vlan": null,
        "id": 5004,
        "secondary_rack": null,
        "fabric_id": 0,
        "space": "undefined",
        "fabric": "fabric-0",
        "name": "Storage network",
        "primary_rack": null,
        "resource_uri": "/MAAS/api/2.0/vlans/5004/"
    },
    "parents": [
        "ens3"
    ],
    "effective_mtu": 1500,
    "links": [
        {
            "id": 55,
            "mode": "link_up"
        }
    ],
    "discovered": null,
    "name": "ens3.100",
    "resource_uri": "/MAAS/api/2.0/nodes/4efwb4/interfaces/21/"
}

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How to delete a VLAN interface

VLAN interfaces can only be deleted via the MAAS CLI. Select the “CLI” dropdown above to see how.

The following command outlines the syntax required to delete a VLAN interface from the command line:

maas $PROFILE vlan delete $FABRIC__ID $VLAN_ID

Using the values from previous examples, you executed this step as follows:

maas admin vlan delete 0 100