Specifications

CHAPTER 2

VLAN Implementation

Configuring an EtherChannel

Basically, you should configure the logical interface and then put the physical interfaces into the channel group:

(config)# interface port-channel number

![any additional configuration, such as trunking for a Layer 2 EtherChannel]

For a Layer 3 EtherChannel, add the following:

(config-if)# no switchport

(config-if)# ip address address mask

Then, at each port that is part of the EtherChannel, use the following:

(config)# interface { number | range interface – interface}

(config-if)# channel-group number mode {auto | desirable | on}

Putting the IP address on the Port Channel interface creates a Layer 3 EtherChannel. Simply putting interfaces into a

channel group creates a Layer 2 EtherChannel, and the logical interface is automatically created.

The Cisco proprietary Port Aggregation Protocol (PAgP) dynamically negotiates the formation of a channel. There are

three PAgP modes:

n On: The port channels without using PAgP negotiation. The port on the other side must also be set to On.

n Auto: Responds to PAgP messages but does not initiate them. Port channels if the port on the other end is set to

Desirable. This is the default mode.

n Desirable: Port actively negotiates channeling status with the interface on the other end of the link. Port channels if

the other side is Auto or Desirable.

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CCNP SWITCH 642-813 Quick Reference by Denise Donohue

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