vlan 20 interface GigabitEthernet3/1 description Link #1 in Po1 Chapter 7: Link Aggregation no ip address switchport channel-group - 1 mode desirable interface GigabitEthernet3/2 description Link #2 in Po1 no ip address switchport channel-group 1 mode desirable interface GigabitEthernet3/3 description Link #3 in Po1 no ip address switchport channel-group 1 mode desirable interface GigabitEthernet3/4 description Link #4 in Po1 no ip address switchport channel-grou 1 mode desirable On IOS switches, the quick way to see the status of an EtherChannel is to use the show etherchannel summary command. CatOS users may be frustrated by the complexity of the output. First, you must figure out the codes, as outlined in the included legend; then, you can determine the status of your EtherChannel. In this example, the Ether- Channel is Layer2 and is in use (Po1(SU)). The individual physical links are all active, as they have (P) next to their port numbers: Switch-1-IOS#sho - etherchannel summary Flags: D - down P - in port-channel I - stand-alone S - suspended H - Hot-standby (LACP only) R Layer3 S - Layer2 U in use f - failed to allocate aggregator u - unsuitable for bundling Number of channel-groups in use: 1 Number of aggregators: Group Port -channel - Protocol Ports Po1 (SU) Gi3/1(P) Gi3/2(P) Gi3/3(P) Gi3/4(P) A more useful command, though missing the real status of the interfaces, is the show etherchannel command. This command is interesting in that it shows the number of bits used in the hash algorithm for each physical interface, as illustrated previously in Figure 7-3. Also of interest in this command's output is the fact that it displays the last time at which an interface joined the EtherChannel: Switch-1-IOS #sho etherchannel 1 port-channel Port-channels in the group: EtherChannel Port-channel: Po1 Age of the Port-channel = 1d:09h:22m:37s Logical slot/port = 14/6 Number of ports = 4 = 0x00580001 HotStandBy port = null Port state = Port-channel Ag-Inuse Protocol = PAgP Ports in the Port-channel: Index EC state No of