Which statement describes what happens to all ports in the bundle?

A network engineer changed the port speed and duplex setting of an existing EtherChannel bundle that uses the PAgP protocol.

Which statement describes what happens to all ports in the bundle?
A . PAgP changes the port speed and duplex for all ports in the bundle.
B . PAgP drops the ports that do not match the configuration.
C . PAgP does not change the port speed and duplex for all ports in the bundle until the switch is rebooted.
D . PAgP changes the port speed but not the duplex for all ports in the bundle.

View Answer

Answer: A

Explanation:

PAgP aids in the automatic creation of EtherChannel links. PAgP packets are sent between EtherChannel­capable ports in order to negotiate the formation of a channel. Some restrictions are deliberately introduced into PAgP.

The restrictions are:

PAgP does not form a bundle on ports that are configured for dynamic VLANs. PAgP requires that all ports in the channel belong to the same VLAN or are configured as trunk ports. When a bundle already exists and a VLAN of a port is modified, all ports in the bundle are modified to match that VLAN.

PAgP does not group ports that operate at different speeds or port duplex. If speed and duplex change when a bundle exists, PAgP changes the port speed and duplex for all ports in the bundle.

PAgP modes are off, auto, desirable, and on. Only the combinations auto-desirable, desirable- desirable, and on-on allow the formation of a channel. The device on the other side must have PAgP set to on if a device on one side of the channel does not support PAgP, such as a router.

Reference: http:// www.cisco.com/c/ en/us/support/docs/lan-switching/etherchannel/12023-4.html