Cisco WS-SUP32-GE-3B Software Configuration Guide - Page 151

Chapter 10 Configuring EtherChannels EtherChannel Feature Configuration Guidelines and Restrictions EtherChannel load balancing can use MAC addresses or IP addresses. EtherChannel load balancing can also use Layer 4 port numbers. EtherChannel load balancing can use either source or destination or both source and destination addresses or ports. The selected mode applies to all EtherChannels configured on the switch. EtherChannel load balancing can use MPLS Layer 2 information. Use the option that provides the balance criteria with the greatest variety in your configuration. For example, if the traffic on an EtherChannel is going only to a single MAC address and you use the destination MAC address as the basis of EtherChannel load balancing, the EtherChannel always chooses the same link in the EtherChannel; using source addresses or IP addresses might result in better load balancing. EtherChannel Feature Configuration Guidelines and Restrictions When EtherChannel interfaces are configured improperly, they are disabled automatically to avoid network loops and other problems. To avoid configuration problems, observe these guidelines and restrictions: • The commands in this chapter can be used on all LAN ports in Catalyst 6500 series switches, including the ports on the supervisor engine and a redundant supervisor engine. • The WS-X6148-GE-TX and WS-X6148V-GE-TX switching modules do not support more than 1 Gbps of traffic per EtherChannel. • When you add a member port that does not support ISL trunking to an EtherChannel, Cisco IOS software automatically adds a switchport trunk encapsulation dot1q command to the port-channel interface to prevent configuration of the EtherChannel as an ISL trunk. The switchport trunk encapsulation dot1q command is inactive when the EtherChannel is not a trunk. • All Ethernet LAN ports on all modules, including those on a redundant supervisor engine, support EtherChannels (maximum of eight LAN ports) with no requirement that the LAN ports be physically contiguous or on the same module. • Configure all LAN ports in an EtherChannel to use the same EtherChannel protocol; you cannot run two EtherChannel protocols in one EtherChannel. • Configure all LAN ports in an EtherChannel to operate at the same speed and in the same duplex mode. • LACP does not support half-duplex. Half-duplex ports in an LACP EtherChannel are put in the suspended state. • Enable all LAN ports in an EtherChannel. If you shut down a LAN port in an EtherChannel, it is treated as a link failure and its traffic is transferred to one of the remaining ports in the EtherChannel. • An EtherChannel will not form if one of the LAN ports is a Switched Port Analyzer (SPAN) destination port. • For Layer 3 EtherChannels, assign Layer 3 addresses to the port channel logical interface, not to the LAN ports in the channel. • For Layer 2 EtherChannels: - Assign all LAN ports in the EtherChannel to the same VLAN or configure them as trunks. - If you configure an EtherChannel from trunking LAN ports, verify that the trunking mode is the same on all the trunks. LAN ports in an EtherChannel with different trunk modes can operate unpredictably. OL-11439-03 Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY 10-5