Etherchannel And Switch Stacks - Cisco 3032 Software Configuration Manual

Chapter 37 Configuring EtherChannels and Link-State Tracking
forwarding on the switch EtherChannel ensures that the switch uses all available bandwidth to the router.
The router is configured for destination-based forwarding because the large number of workstations
ensures that the traffic is evenly distributed from the router EtherChannel.
Use the option that provides the greatest variety in your configuration. For example, if the traffic on a
channel is going only to a single MAC address, using the destination-MAC address always chooses the
same link in the channel. Using source addresses or IP addresses might result in better load-balancing.
Figure 37-5
Blade
Server 1
Client

EtherChannel and Switch Stacks

If a stack member that has ports participating in an EtherChannel fails or leaves the stack, the stack
master removes the failed stack member switch ports from the EtherChannel. The remaining ports of the
EtherChannel, if any, continue to provide connectivity.
When a switch is added to an existing stack, the new switch receives the running configuration from the
stack master and updates itself with the EtherChannel-related stack configuration. The stack member
also receives the operational information (the list of ports that are up and are members of a channel).
When two stacks merge that have EtherChannels configured between them, self-looped ports result.
Spanning tree detects this condition and acts accordingly. Any PAgP or LACP configuration on a
winning switch stack is not affected, but the PAgP or LACP configuration on the losing switch stack is
lost after the stack reboots.
OL-12247-04
Load Distribution and Forwarding Methods
Blade
Server 16
Blade Switch with
source-based
forwarding enabled
EtherChannel
Cisco router
with destination-based
forwarding enabled
Client
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
Understanding EtherChannels
37-9