Port Aggregation Protocol; Pagp Modes - Cisco IE-4000 Software Configuration Manual

Configuring EtherChannels
Information About Configuring EtherChannels
Figure 109 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
where you apply the configuration. To change the parameters of all ports in an EtherChannel, apply configuration
commands to the port-channel interface, for example, spanning-tree commands or commands to configure a Layer 2
EtherChannel as a trunk.

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.
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.

PAgP Modes

Table 69User-Configurable EtherChannel PAgP Modes, page 1030
modes for the channel-group interface configuration command.
Logical
port-channel
Channel-group
binding
1029
Physical ports
shows the user-configurable EtherChannel PAgP