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    Understanding QFX Series Virtual Chassis Port Link Aggregation

    You can combine physical Ethernet ports belonging to different member switches of a Virtual Chassis configuration to form a logical point-to-point link, known as a link aggregation group (LAG) or bundle. A LAG provides more bandwidth than a single Ethernet link can provide. Additionally, link aggregation provides network redundancy by load-balancing traffic across all available links. If one of the links fails, the system automatically load-balances traffic across all remaining links.

    Similarly, if a Virtual Chassis member switch that has LAG member interfaces on multiple member switches fails for any reason, the traffic traversing the LAG can be redirected through the active member switch. This setup has benefits for failover purposes and can be especially beneficial in cases when a member switch needs to be inactive for some time.

    You can configure any optical uplink port that can be used to connect QFX devices configured as standalone switches together into a Virtual Chassis port (VCP). You can configure multiple optical uplink interfaces between two member switches in the same Virtual Chassis as VCPs. If you have configured two or more optical ports as VCPs connecting the same member switches, the optical uplink ports configured as VCPs automatically form a LAG provided the optical uplink ports are configured to operate at the same link speeds. Each LAG is assigned a positive-integer identifier called a trunk ID.

    A LAG over uplink VCPs provides higher overall bandwidth for forwarding traffic between the member switches connected by the optical VCPs, faster management communications, and greater redundancy of operations among the members than would be available without the LAG. A LAG over optical VCPs provides an additional Virtual Chassis link throughput for the switches.

    Note: The interfaces that are included within a bundle or LAG are sometimes referred to as member interfaces. Do not confuse this term with member switches, which refers to switches that are interconnected as a Virtual Chassis. It is possible to create a LAG that is composed of member interfaces that are located in different member switches of a Virtual Chassis.

    Modified: 2016-04-29