Operation Manual – Link AggregationH3C S7500E Series Ethernet Switches Chapter 1 Link Aggregation Overview1-31.2 Approaches to Link AggregationTwo ways are available for implementing link aggregation, as described in Manual LinkAggregation and Static LACP link aggregation.1.2.1 Manual Link AggregationI. OverviewManual aggregations are created manually. Member ports in a manual aggregation areLACP-disabled.II. Port states in a manual aggregationIn a manual aggregation group, ports are either selected or unselected. Selected portscan receive and transmit data frames whereas unselected ones cannot.When setting the state of ports in a manual aggregation group, the system considersthe following:z The system selects the port with the highest priority in the up state as thereference port of the aggregation group. Port priority descends in the followingorder: full duplex/high speed, full duplex/low speed, half duplex/high speed, andhalf duplex/low speed. If multiple ports are of the same priority, the one with thelowest port number is the reference port.z Ports in the up state with the same speed, duplex mode, link state, and basicconfiguration as the reference port become the candidates for selected ports,while the other ports become unselected ports.z There is a limit on the number of selected ports in a manual aggregation group. Ifthe number of selected-port candidates does not reach the limit, all the candidatesbecome selected ports; if the number of candidates exceeds the limit, thecandidates with lower port numbers become selected ports, while the othercandidates become unselected ports.z The selected port with the lowest port number serves as the master port of theaggregation group, and the other ports serve as the member ports of theaggregation group.z If all the ports of an aggregations port are down, the port with the lowest portnumber is the master port. In this case, all of them are unselected ports.In addition, unless the master port should be selected, a port that joins the group afterthe limit is reached will not be placed in selected state even if it should be in normalcases. This is to prevent the ongoing service on selected ports from being interrupted.You need to avoid the situation however as the selected/unselected state of a port maybecome different after a reboot.
