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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-06
Chapter 34 Configuring EtherChannels and Link-State Tracking
Understanding EtherChannels
Figure 34-2 Relationship of Physical Ports, Logical Port Channels, and Channel Groups
After you configure an EtherChannel, configuration changes applied to the port-channel interface apply
to all the physical ports assigned to the port-channel interface. Configuration changes applied to the
physical port affect only the port to which you apply the configuration. To change the parameters of all
ports in an EtherChannel, apply the configuration commands to the port-channel interface.
Port Aggregation Protocol
The Port Aggregation Protocol (PAgP) is a Cisco-proprietary protocol that can be run only on Cisco
switches and on those switches licensed by vendors to support PAgP. PAgP facilitates the automatic
creation of EtherChannels by exchanging PAgP packets between Ethernet ports.
Note PAgP is only available on network node interfaces (NNIs) and enhanced network interfaces (ENIs).
By using PAgP, the switch learns the identity of partners capable of supporting PAgP and the capabilities
of each port. It then dynamically groups similarly configured ports into a single logical link (channel or
aggregate port). Similarly configured ports are grouped based on hardware, administrative, and port
parameter constraints. For example, PAgP groups the ports with the same speed, duplex mode, native
VLAN, VLAN range, and trunking status and type. After grouping the links into an EtherChannel, PAgP
adds the group to the spanning tree as a single switch port.
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Channel-group
binding
Physical ports
Logical
port-channel