Ethernet Channel bundling changes Full-duplex links to Half-duplex

etherchannel

I have three switches connected to each other with two links (one of them is a redundant link using STP), but I have configured EtherChannel so that both the links work together as a bundle,

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What i know about EtherChannel is, if we bundle two 100Mbps links together, the speed of the bundle will be 200MBps, but the initial status of both the links must be the same.

Now, Before configuring EtherChannel, the speed of each single Fast Ethernet link was 100Mbps and all links were in full-duplex mode,

but after I configured the links to work as a bundle, the mode of each port-channel interface is changed to half-duplex and the speed is changed to 300mbps instead of 200Mbps.

As you can see in the following output,

show interfaces port-channel 1
Port-channel 1 is up, line protocol is up (connected)
  Hardware is EtherChannel, address is 0030.f22d.b05d (bia 0030.f22d.b05d)
  Description: Trunking with SW_Access1
  MTU 1500 bytes, BW 300000 Kbit, DLY 1000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Half-duplex, 300Mb/s

before configuring the etherchannel, the speed and duplex mode of individual links were 100Mbps, and full-duplex respectively.

Why the mode is changed to half-duplex from full-duplex after configuring EtherChannel ? and how come the speed is 3 times of 100Mbps instead of 2 ?

Best Answer

interface po1 defines the link(s) to be half-duplex. (show run int po1)

It's 300Mbps because you have three links assigned (and active) in the channel-group. (show etherchannel 1 port-channel)

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