Configure Aggregated Ethernet Interfaces

Link aggregation of Ethernet interfaces is defined in the IEEE 802.3ad standard. The JUNOS implementation of 802.3AD balances traffic across the member links within an aggregated Ethernet bundle based on the Layer 3 information carried in the packet. This implementation uses the same load balancing algorithm used for per-packet load balancing. For information about per-packet load balancing, see the JUNOS Internet Software Guide: Routing and Routing Protocols.

The JUNOS software does not provide load balancing for multicast traffic on aggregated interfaces. If a link carrying multicast data goes down, another link carries the traffic. This provides redundancy, not more bandwidth.

You configure an aggregated Ethernet virtual link by specifying the link number as a physical device and then associating a set of ports that have the same speed and are in full-duplex mode. The physical interfaces can be either Fast Ethernet, Gigabit Ethernet, or 10-Gigabit Ethernet devices; however, do not use a combination of these within the same aggregated link.

To specify aggregated Ethernet interfaces, include the vlan-tagging statement at the [edit interfaces aex] hierarchy level:

[edit interfaces aex]

vlan-tagging;

You must also include the vlan-id statement:

vlan-id number;

You can configure this statement at the following hierarchy levels:

• [edit interfaces interface-name unit logical-unit-number]
• [edit logical-routers logical-router-name interfaces interface-name unit logical-unit-number]

By default, no aggregated Ethernet interfaces are created. You must define the number of aggregated Ethernet interfaces by including the device-count statement at the [edit chassis aggregated-devices ethernet] hierarchy level:

[edit chassis]

aggregated-devices {

    ethernet {

        device-count number;

    }

}

The maximum number of aggregated interfaces is 128, and the assigned number can range from 1 through 128. For information about configuring aggregated devices, see the JUNOS Internet Software Configuration Guide: Getting Started.

You must also specify the constituent physical links by including the 802.3ad statement at the [edit interfaces interface-name fastether-options] or [edit interfaces interface-name gigether-options] hierarchy level; for more information, see Configure Ethernet Link Aggregation. You can optionally specify other physical properties that apply specifically to the aggregated Ethernet interfaces; for details, see Configure Ethernet Physical Interface Properties. For a sample configuration, see Example: Configure Aggregated Ethernet Interfaces.

To delete an aggregated Ethernet interface from the configuration, issue the delete interfaces aex command at the [edit] hierarchy level in configuration mode:

[edit]

user@host# delete interfaces aex

If you delete an aggregated Ethernet interface from the configuration, the JUNOS software removes the configuration statements related to aex and sets this interface to down state. However, the aggregated Ethernet interface is not deleted until you delete the chassis aggregated-devices ethernet device-count configuration statement.