Cisco SD2008T-NA Configuration Manual page 83

Chapter 3 Configuring Ports and Interfaces
When a 4404 controller or WiSM controller module LAG port is connected to a Catalyst 3750G or 6500
Note
channel group employing load balancing, note the following:
LAG requires the etherchannel to be configured for the "on" mode on both the controller and the
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Catalyst switch.
Once the etherchannel is configured as "on," at both ends of the link, it does not matter if the Catalyst
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switch is configured with either Link Aggregation Control Protocol (LACP) or Cisco proprietary
Port Aggregation Protocol (PAgP) because no channel negotiation is done between the controller
and the switch. Additionally, LACP and PAgP are not supported on the controller.
However, the load-balancing method configured on the Catalyst switch must be a load-balancing
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method that terminates all IP datagram fragments on a single controller port. Not following this
recommendation may result in problems with access point association.
The recommended load-balancing method for Catalyst switches is src-dest-ip (Command line
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interface command: port-channel load-balance src-dest-ip).
The Catalyst 6500 series switches running in PFC3 or PFC3CXL mode implement enhanced
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EtherChannel load balancing. The enhanced EtherChannel load balancing adds the VLAN number
to the hash function, which is incompatible with LAG. From Release 12.2(33)SXH and later
releases, Catalyst 6500 IOS software offers the exclude vlan keyword to the port-channel
load-balance command to implement src-dst-ip load distribution. See the Cisco IOS Interface and
Hardware Component Command Reference guide for more information.
Enter the show platform hardware pfc mode command on the Catalyst 6500 switch to confirm the
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PFC operating mode.
The following example shows a Catalyst 6500 series switch in PFC3B mode when you enter the
global configuration port-channel load-balance src-dst-ip command for proper LAG
functionality:
# show platform hardware pfc mode PFC operating mode
PFC operating mode : PFC3B
# show EtherChannel load-balance
EtherChannel Load-Balancing Configuration:
src-dst-ip
The following example shows Catalyst 6500 series switch in PFC3C mode when you enter the
exclude vlan keyword in the port-channel load- balance src-dst-ip exclude vlan command.
# show platform hardware pfc mode
PFC operating mode : PFC3C
# show EtherChannel load-balance
EtherChannel Load-Balancing Configuration:
src-ip enhanced
# mpls label-ip
If the recommended load-balancing method cannot be configured on the Catalyst switch, then
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configure the LAG connection as a single member link or disable LAG on the controller.
OL-9141-03
Cisco Wireless LAN Controller Configuration Guide
Enabling Link Aggregation
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