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Cisco ME 3400 EthernetAccess Switch SoftwareConfiguration Guide
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Chapter31 Configuring EtherChannels
Understanding EtherChannels
Figure31-2 Relationship of Physical Ports, Logical Port Channels, and Channel Groups
After you configure an EtherChannel, configurati on chan ges appli ed to th e port -ch anne l inter fa ce ap ply
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 configur at ion. To change the parameters of all
ports in an EtherChannel, apply the configuration comm an ds to th e p ort -cha nn el int erfac e.
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).
By using PAgP, the switch learns the iden tity of partners capable of supportin g PAgP and the capabilities
of each port. It then dynamically groups similarly configured ports in to a single logical link (channel or
aggregate port). Similarly configured ports are grouped based on ha rdware , a dmin istr ative, and p ort
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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