Understanding Administrative Groups; Understanding Etherchannel Ids; Understanding Port Aggregation Protocol - Cisco WS-X6066-SLB-APC - Content Switching Module Software Manual

Understanding How EtherChannel Works
The network device to which a Catalyst 6000 family switch is connected may impose its own limits
Note
on the number of ports in an EtherChannel.
If a segment within an EtherChannel fails, traffic previously carried over the failed link switches to the
remaining segments within the EtherChannel. A trap is sent upon a failure identifying the switch, the
EtherChannel, and the failed link. Inbound broadcast and multicast packets on one segment in an
EtherChannel are blocked from returning on any other segment of the EtherChannel.
You can configure EtherChannels as trunks. After a channel is formed, configuring any port in the
channel as a trunk applies the configuration to all ports in the channel. Identically configured trunk ports
can be configured as an EtherChannel.
These sections describe EtherChannel:
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Understanding Administrative Groups

Configuring an EtherChannel creates an administrative group, designated by an integer between 1 and
1024, to which the EtherChannel belongs. When an administrative group is created, you can assign an
administrative group number or let the next available administrative group number be assigned
automatically. Forming a channel without specifying an administrative group number creates a new
automatically numbered administrative group. An administrative group may contain a maximum of eight
ports.

Understanding EtherChannel IDs

Each EtherChannel is automatically assigned a unique EtherChannel ID. Use the show channel group
admin_group command to display the EtherChannel ID.

Understanding Port Aggregation Protocol

The Port Aggregation Protocol (PAgP) facilitates the automatic creation of EtherChannels by
exchanging packets between Ethernet ports. PAgP packets are exchanged only between ports in auto
and desirable modes. Ports configured in on or off mode do not exchange PAgP packets. The protocol
learns the capabilities of port groups dynamically and informs the other ports. After PAgP identifies
correctly matched EtherChannel links, it groups the ports into an EtherChannel. The EtherChannel is
then added to the spanning tree as a single bridge port.
EtherChannel includes four user-configurable modes: on, off, auto, and desirable. Only auto and
desirable are PAgP modes. You can modify the auto and desirable modes with the silent and
non-silent keywords. By default, ports are in auto silent mode.
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
6-2
Understanding Administrative Groups, page 6-2
Understanding EtherChannel IDs, page 6-2
Understanding Port Aggregation Protocol, page 6-2
Understanding Frame Distribution, page 6-3
Chapter 6 Configuring EtherChannel
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