Understanding Link Aggregation
You can combine multiple physical Ethernet ports 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. In a Virtual Chassis, LAGs can be used to load-balance network traffic between member switches.
The maximum number of interfaces that can be grouped into a LAG and the maximum number of LAGs supported on a switch varies according to the switch model and the version of and the version of Juniper Networks Junos operating system (Junos OS) that is running on that switch. Table 1 lists the maximum number of interfaces per LAG and the maximum number of LAGs that are supported on EX Series switches running Junos OS Release 19.1. If your switch is running a different version of Junos OS, refer to the device specific documentation, EX Series Ethernet Switches, before implementing LAG in your network.
Table 1: Maximum Interfaces per LAG and Maximum LAGs per Switch
Maximum Interfaces per LAG