Command Line Interface
4-98
Link Aggregation Commands
Ports can be statically grouped into an aggregate link (i.e., trunk) to increase the
bandwidth of a network connection or to ensure fault recovery. Or you can use the
Link Aggregation Control Protocol (LACP) to automatically negotiate a trunk link
between this switch and another network device. For static trunks, the switches have
to comply with the Cisco EtherChannel standard. For dynamic trunks, the switches
have to comply with LACP. This switch supports up to six trunks. For example, a
trunk consisting of two 1000 Mbps ports can support an aggregate bandwidth of
4 Gbps when operating at full duplex.
Guidelines for Creating Trunks
General Guidelines –
• Finish configuring port trunks before you connect the corresponding network
cables between switches to avoid creating a loop.
• A trunk can have two Gigabit optional module ports.
• The ports at both ends of a connection must be configured as trunk ports.
• All ports in a trunk must be configured in an identical manner, including
communication mode (i.e., speed, duplex mode and flow control), VLAN
assignments, and CoS settings.
• All the ports in a trunk have to be treated as a whole when moved from/to, added
or deleted from a VLAN via the specified port-channel.
• STP, VLAN, and IGMP settings can only be made for the entire trunk via the
specified port-channel.
Dynamically Creating a Port Channel –
Ports assigned to a common port channel must meet the following criteria:
• Ports must have the same LACP system priority.
• Ports must have the same port admin key (Ethernet Interface).
• If the port channel admin key (lacp admin key - Port Channel) is not set when a
channel group is formed (i.e., it has the null value of 0), this key is set to the
same value as the port admin key (lacp admin key - Ethernet Interface) used by
the interfaces that joined the group.
Command Function Mode Page
Manual Configuration Commands
interface port-channel Configures a trunk and enters interface
configuration mode for the trunk
GC 4-84
channel-group Adds a port to a trunk IC (Ethernet) 4-99
Dynamic Configuration Command
lacp Configures LACP for the current interface IC (Ethernet) 4-99
Trunk Status Display Command
show interfaces status
port-channel
Shows trunk information NE, PE 4-91
show lacp Shows LACP information PE 4-99
