DELL PC7024 User Manual

Port Channel Commands

A LAG can be either static or dynamic not both. It cannot have some 

members participate in the protocol while other members not participate. 

Additionally, it is not possible to change a LAG from static to dynamic via the 

CLI. You must remove the member ports from the static LAG and then add 

them to the dynamic LAG.

When members are added to a LAG, they are removed from all existing 

VLAN membership. When members are removed from a LAG, the members 

rejoin the VLANs that they were previously members of as per the 

configuration file.
The LAG interface can be a member of a VLAN complying with IEEE 

802.1Q.

In many implementations, a LAG is declared as up if any one of its member 

ports is active. This enhancement provides configurability for the minimum 

number of member links to be active to declare a LAG up. Network 

administrators can also utilize this feature to automatically declare a LAG 

down when only some of the links have failed. 

Trunking, which is also called Port Channels or Link Aggregation, is initiated 

and maintained by the periodic exchanges of Link Aggregation Control PDUs 

(LACPDUs). When LACP is enabled for a physical interface, LACPDUs 

must not be dropped for any reason. Conversely, when LACP is disabled for 

the physical interface LACPDUs must be dropped. 
From a system perspective, a LAG is treated as a physical port. A LAG and a 

physical port use the same configuration parameters for administrative 

enable/disable, port priority, and path cost. When a physical port is 

configured as part of a LAG, it no longer participates in forwarding operations 

until the LAG becomes active.

2CSPC4.XCT-SWUM2XX1.book  Page 624  Monday, October 3, 2011  11:05 AM