Trunk aggregations are based on the IEEE 802.3ad standard and work by enabling multiple flows of traffic to be spread across a set of aggregated ports. IEEE 802.3ad requires switch configuration, as well as switch-vendor proprietary extensions in order to work across multiple switches. In trunk aggregations, the clients configured over the aggregations get a consolidated bandwidth of the underlying links, because each network port is associated with every configured datalink over the aggregation. When you create a link aggregation, the aggregation is by default created in the trunk mode. You might use a trunk aggregation in the following situations:
For systems in the network that run applications with distributed heavy traffic, you can dedicate a trunk aggregation to that application's traffic to take advantage of the increased bandwidth.
For sites with limited IP address space that require large amounts of bandwidth, you need only one IP address for the trunk aggregation of datalinks.
For sites that need to hide any internal datalinks, the IP address of the trunk aggregation hides these datalinks from external applications.
For applications that need reliable network connection, trunk aggregation protects network connections against link failure.
Trunk aggregation supports the following features:
Using a switch
Using a switch with the Link Aggregation Control Protocol (LACP)
Back-to-back trunk aggregation configuration
Aggregation policies and load balancing
The following sections describe the features of trunk aggregations.