Cisco Gigabit Ethernet Switch Module for HP p-Class BladeSystem Software Configuration Guide

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Cisco Gigabit Ethernet Switch Module for HP p-Class BladeSystem Software Configuration Guide
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Chapter 28 Configuring EtherChannels and Layer 2 Trunk Failover
Understanding EtherChannels
EtherChannel Overview
An EtherChannel consists of individual Gigabit Ethernet links bundled into a single logical link as
shown in Figure 28-1.
Figure 28-1 Typical EtherChannel Configuration
In Figure 28-1, the EtherChannel provides full-duplex bandwidth up to 8 Gb/s (Gigabit EtherChannel)
between your switch and another switch or host.
Each EtherChannel can consist of up to eight compatibly configured Ethernet ports. All ports in each
EtherChannel must be configured as Layer 2 ports. The number of EtherChannels is limited to 48. For
more information, see the “EtherChannel Configuration Guidelines” section on page 28-9.
You can configure an EtherChannel in one of these modes: Port Aggregation Protocol (PAgP), Link
Aggregation Control Protocol (LACP), or On. Configure both ends of the EtherChannel in the same
mode:
• When you configure one end of an EtherChannel in either PAgP or LACP mode, the system
negotiates with the other end of the channel to determine which ports should become active. In
previous releases, the incompatible ports were suspended. Beginning with Cisco IOS Release
12.2(35)SE, instead of a suspended state, the local port is put into an independent state and continues
to carry data traffic as would any other single link. The port configuration does not change, but the
port does not participate in the EtherChannel.
• When you configure an EtherChannel in the on mode, no negotiations take place. The switch forces
all compatible ports to become active in the EtherChannel. The other end of the channel (on the other
switch) must also be configured in the on mode; otherwise, packet loss can occur.
If a link within an EtherChannel fails, traffic previously carried over that failed link moves to the
remaining links within the EtherChannel. If traps are enabled on the switch, a trap is sent for a failure
that identifies the switch, the EtherChannel, and the failed link. Inbound broadcast and multicast packets
on one link in an EtherChannel are blocked from returning on any other link of the EtherChannel.
Catalyst 6500
series switch
Gigabit EtherChannel
Blade
Switch
Blade
Server 1
Blade
Server 16
119704