68 CHAPTER 3: P ORT O PERATIONEthernet PortTroubleshootingFault: Default VLAN ID configuration failed.Troubleshooting: Take the following steps.1 Use the display interface or display port command to check if the port is atrunk port or a hybrid port. If it is neither, configure it as a trunk port or a hybrid port.2 Configure the default VLAN ID.Link AggregationConfigurationBrief Introduction to Link AggregationLink aggregation means aggregating several ports together to implement theoutgoing/incoming payload balance among the member ports and enhance theconnection reliability. Link aggregation includes manual aggregation, dynamic LACPaggregation, and static LACP aggregation. In terms of load sharing, link aggregationmay be load sharing aggregation and non-load sharing aggregation.For the member ports in an aggregation group, their basic configurations must be thesame. That is, if one is a trunk port, the others must also be; when it turns into accessport, then others must change to access port.The basic configuration includes STP setting, QoS setting, VLAN setting, and portsetting. The STP setting includes STP enabling/disabling, link attribute (point-to-pointor not), STP priority, path cost, max transmission speed, loop protection, rootprotection, edge port or not. The QoS setting includes traffic limiting, prioritymarking, default 802.1p priority, bandwidth assurance, congestion avoidance, trafficredirection, traffic statistics. The VLAN setting includes permitted VLAN types, anddefault VLAN ID. The port setting includes port link type.The Switch 5500-SI 28-Port can support up to 14 aggregation groups, the Switch5500-SI 52-Port can support up to 26 aggregation groups, and the Switch 5500-EISeries can support up to 32 aggregation groups. Each group can have a maximum ofeight 100 Mbps Ethernet ports or four Gigabit SFP ports. For the Switch 5500-SIseries, the ports in an aggregation group must physically belong to the same unit, butfor the Switch 5500-EI series, an aggregation group can contain ports whichphysically belong to different units.Brief Introduction to LACPIEEE802.3ad-based Link Aggregation control protocol (LACP) implements dynamiclink aggregation and disaggregation and exchanges information with the peerthrough LACP data unit (LACPADU). When LACP is enabled on it, the port notifies,through sending LACPDU, the peer of its system priority, system MAC, port priority,port number and operation key. On receiving this information, the peer compares thereceived information with that stored at other ports to determine which ports can beaggregated, so that the two parties can agree on adding/deleting which portinto/from a certain dynamic aggregation group.The operation key is a configuration set generated by LACP based on port setting(speed, duplex mode, basic configuration and management key). When LACP isenabled, the management key of a dynamic aggregation port is 0 by default, but themanagement key of a static aggregation port consists with the aggregation group ID.For a dynamic aggregation group, all member ports must have the same operationkey, while for a manual or static aggregation group, only the active member portsmust have the same operation key.
