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mc-ae

Syntax

Hierarchy Level

Description

Enable multichassis link aggregation groups (MC-LAG), which enables one device to form a logical LAG interface with two or more other devices.

Options

chassis-id

Specify the chassis ID for Link Aggregation Control Protocol (LACP) to calculate the port number of MC-LAG physical member links. Each MC-LAG peer should have a unique chassis ID.

  • Values: 0 or 1
events

Specify an action if a specific MC-LAG event occurs.

iccp-peer-down

Specify an action if the ICCP peer of this node goes down.
force-icl-down

If the node’s ICCP peer goes down, bring down the interchassis-link logical interface.
prefer-status-control-active

Specify that the node configured as status-control active become the active node if the peer of this node goes down.

When ICCP goes down, you can use this keyword to make a mc-lag PE to become the active PE. For example, if you want mc-lag PE1 to be Active on ICCP down, then configure this keyword in PE1. It is not recommended to configure this keyword in both the mc-lag PEs.

Note:

The prefer-status-control-active statement can be configured with the status-control standby configuration to prevent the LACP MC-LAG system ID from reverting to the default LACP system ID on ICCP failure. Use this configuration only if you can ensure that ICCP will not go down unless the router or switch is down. You must also configure the hold-time down value (at the [edit interfaces interface-name] hierarchy level) for the interchassis link with the status-control standby configuration to be higher than the ICCP BFD timeout. This configuration prevents data traffic loss by ensuring that when the router or switch with the status-control active configuration goes down, the router or switch with the status-control standby configuration does not go into standby mode.

To make the prefer-status-control-active configuration work with the status-control standby configuration when an interchassis-link logical interface is configured on aggregate Ethernet interface, you must either configure the lacp periodic interval statement at the [edit interface interface-name aggregated-ether-options] hierarchy level as slow or configure the detection-time threshold statement at the [edit protocols iccp peer liveness-detection] hierarchy level as less than 3 seconds.
init-delay-time seconds

To minimize traffic loss, specify the number of seconds in which to delay bringing the multichassis aggregated Ethernet interface back to the up state when you reboot an MC-LAG peer. By delaying the startup of the interface until after protocol convergence, you can prevent packet loss during the recovery of failed links and devices.

Note:

On QFX and EX Series switches, the default session establishment hold time is 300 seconds. However, the session establishment time must be at least 100 seconds higher than the init delay time. You can optionally update the session establishment time to be 340 seconds and the init delay time to be 240 seconds.
mc-ae-id mc-ae-id

Specify the identification number of the MC-LAG device. The two MC-LAG network devices that manage a given MC-LAG must have the same identification number.

  • Range: 1 through 65,535
mode (active-active | active-standby)

Specify whether the MC-LAG is in active-active or active-standby mode. Chassis that are in the same group must be in the same mode.

Note:

You can configure IPv4 (inet) and IPv6 (inet6) addresses on mc-ae interfaces when the active-standby mode is configured.

In active-active mode, all member links are active on the MC-LAG. In this mode, media access control (MAC) addresses learned on one MC-LAG peer are propagated to the other MC-LAG peer. Active-active mode is a simple and deterministic design and is easier to troubleshoot than active-standby mode.

Note:

Active-active mode is not supported on Dense Port Concentrator (DPC) line cards. Instead, use active-standby mode.

In active-active MC-LAG topologies, network interfaces are categorized into three interface types, as follows:

  • S-Link—Single-homed link (S-Link) terminating on an MC-LAG peer device

  • MC-Link—MC-LAG link

  • ICL—Inter-chassis link

  • Mode

    Indicates whether an MC-LAG is in active-standby mode or active-active mode. Chassis that are in the same group must be in the same mode.

    In active-active mode, all member links are active on the MC-LAG. In this mode, media access control (MAC) addresses learned on one MC-LAG peer are propagated to the other MC-LAG peer. Active-active mode is a simple and deterministic design and is easier to troubleshoot than active-standby mode.

    Note:

    Active-active mode is not supported on Dense Port Concentrator (DPC) line cards. Instead, use active-standby mode.

    Depending on the incoming and outgoing interface types, some constraints are added to the Layer 2 forwarding rules for MC-LAG configurations. The following data traffic forwarding rules apply.

    Note:

    If only one MC-LAG member link is in the up state, it is considered an S-Link.

    • When an MC-LAG network receives a packet from a local MC-Link or S-Link, the packet is forwarded to other local interfaces, including S-Links and MC-Links based on the normal Layer 2 forwarding rules and on the configuration of the mesh-group and no-local-switching statements. If MC-Links and S-Links are in the same mesh group and their no-local-switching statements are enabled, the received packets are only forwarded upstream and not sent to MC-Links and S-Links.

    • The following circumstances determine whether or not an ICL receives a packet from a local MC-Link or S-Link:

      • If the peer MC-LAG network device has S-Links or MC-LAGs that do not reside on the local MC-LAG network device

      • Whether or not interfaces on two peering MC-LAG network devices are allowed to talk to each other

    • When an MC-LAG network receives a packet from the ICL, the packet is forwarded to all local S-Links and active MC-LAGs that do not exist in the MC-LAG network from which the packet was sent.

    In active-standby mode, only one of the MC-LAG peers is active at any given time. The other MC-LAG peer is in backup (standby) mode. The active MC-LAG peer uses Link Aggregation Control Protocol (LACP) to advertise to client devices that its child link is available for forwarding data traffic. Active-standby mode should be used if you are interested in redundancy only. If you require both redundancy and load sharing across member links, use active-active mode.

    Note:

    Active-standby mode is not supported on EX4300 and QFX Series switches.
redundancy-group group-id

Specify the redundancy group identification number. The Inter-Chassis Control Protocol (ICCP) uses the redundancy group ID to associate multiple chassis that perform similar redundancy functions. The value you assign to this option must match the value you assign to the redundancy-group-id-list option that you configure on the ICCP peer. If the value differs, when you commit the changes, the system reports a commit check error.

Best Practice:

We recommend that you configure only one redundancy group between MC-LAG nodes. The redundancy group represents the domain of high availability between the MC-LAG nodes. One redundancy group is sufficient between a pair of MC-LAG nodes. If you are using logical systems, then configure one redundancy group between MC-LAG nodes in each logical system.

  • Range: 1 through 4,294,967,294
revert-time

Wait interval (in minutes) before the switchover to the preferred node is performed when the switchover-mode is configured as revertive.

  • Range: 1 through 10
status-control (active | standby)

Specify whether the chassis becomes active or remains in standby mode when an interchassis link failure occurs.

  • Events ICCP-Peer-Down Force-ICL-Down

    Forces the ICL to be down if the peer of this node goes down.

  • Events ICCP-Peer-Down Prefer-Status-Control-Active

    Allows the LACP system ID to be retained during a reboot, which provides better convergence after a failover.
switchover-mode (non-revertive | revertive)

Specify whether Junos OS should trigger a link switchover to the preferred node when the active node is available.

Note:

For revertive mode to automatically switch over to the preferred node, the status-control statement should be configured as active.

Required Privilege Level

interface—To view this statement in the configuration.

interface-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 9.6.

events statement introduced in Junos OS Release 11.4R4 for MX Series routers.

prefer-status-control-active statement introduced in Junos OS Release 13.2R1 for EX Series switches.

init-delay-time seconds statement introduced in Junos OS Release 13.2R3 for EX Series switches.

switchover-mode and revert-time statements introduced in Junos OS Release 13.3.

Support for logical systems introduced in Junos OS Release 14.1.