Ccna 00-301, Volume Official

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ptg29743230

10

Chapter 10: RSTP and EtherChannel Configuration    249

SW1(config-if)# channel-group 1 mode on

SW1(config-if)# ^Z

SW1# show spanning-tree vlan 3

VLAN0003

 Spanning tree enabled protocol ieee

 Root ID    Priority    28675

            Address     0019.e859.5380

            Cost        12

            Port        72 (Port-channel1)

            Hello Time 2 sec  Max Age 20 sec  Forward Delay 15 sec

 Bridge ID  Priority    28675 (priority 28672 sys-id-ext 3)

            Address     0019.e86a.6f80

            Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

            Aging Time  300

Interface           Role Sts Cost      Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Po1                 Root FWD 12        128.64   P2p Peer(STP)

SW1# show etherchannel 1 summary

Flags:  D - down        P - bundled in port-channel

        I - stand-alone s - suspended

        H - Hot-standby (LACP only)

        R - Layer3      S - Layer2

        U - in use      N - not in use, no aggregation

        f - failed to allocate aggregator

        M - not in use, minimum links not met

        m - not in use, port not aggregated due to minimum links not met

        u - unsuitable for bundling

        w - waiting to be aggregated

        d - default port

        A - formed by Auto LAG

Number of channel-groups in use: 1

Number of aggregators: 1

Group  Port-channel  Protocol    Ports

------+-------------+-----------+-----------------------------------------------

1      Po1(SU)          -        Fa0/14(P) Fa0/15(P)

Take a few moments to look at the output in the two show commands in the example, 

as well. First, the show spanning-tree command lists Po1, short for PortChannel1, as 

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ptg29743230

250    CCNA 200-301 Official Cert Guide, Volume 1

an interface. This interface exists because of the channel-group commands using the 

1 parameter. STP no longer operates on physical interfaces Fa0/14 and Fa0/15, instead 

operating on the PortChannel1 interface, so only that interface is listed in the output.

Next, note the output of the show etherchannel 1 summary command. It lists as a heading 

“Port-channel,” with Po1 below it. It also lists both Fa0/14 and Fa0/15 in the list of ports, 

with a (P) beside each. Per the legend, the P means that the ports are bundled in the port 

channel, which is a code that means these ports have passed all the configuration checks and 

are valid to be included in the channel.