Cisco WS-X6K-S2-PFC2 Software Guide - Page 100

EtherChannel Configuration Guidelines Chapter 6 Configuring EtherChannel When configurable, EtherChannel frame distribution can use MAC addresses, IP addresses, and Layer 4 port numbers. You can specify either source or destination address or both source and destination addresses and Layer 4 port numbers. The mode you select applies to all EtherChannels configured on the switch. Use the option that provides the greatest variety in your configuration. For example, if the traffic on a channel is going to a single MAC address only, using source addresses or IP addresses or Layer 4 port numbers as the basis for frame distribution may provide better frame distribution than selecting MAC addresses as the basis. EtherChannel Configuration Guidelines If improperly configured, some EtherChannel ports are disabled automatically to avoid network loops and other problems. Follow these guidelines to avoid configuration problems: • You can have a maximum of eight compatibly configured ports per EtherChannel; the ports do not have to be contiguous or on the same module. Note To configure the EtherChannel across different modules, you must put the ports in the same administrative group using the set port channel port_list admin_group command. • Assign all ports in an EtherChannel to the same VLAN, or configure them as trunk ports. • If you configure the EtherChannel as a trunk, configure the same trunk mode on all the ports in the EtherChannel. Configuring ports in an EtherChannel in different trunk modes can have unexpected results. • An EtherChannel supports the same allowed range of VLANs on all the ports in a trunking EtherChannel. If the allowed range of VLANs is not the same for a port list, the ports do not form an EtherChannel even when set to the auto or desirable mode with the set port channel command. • Ports with different port path costs, set by the set spantree portcost command, can form an EtherChannel as long they are otherwise compatibly configured. Setting different port path costs does not, by itself, make ports incompatible for the formation of an EtherChannel. • Do not configure the ports in an EtherChannel as dynamic VLAN ports. Doing so can adversely affect switch performance. • An EtherChannel will not form with ports that have different GARP VLAN Registration Protocol (GVRP), GARP Multicast Registration Protocol (GMRP), and quality of service (QoS) configurations. • Configure all ports in an EtherChannel to operate at the same speed and duplex mode. • An EtherChannel will not form with ports where the port security feature is enabled. • You cannot enable the port security feature for ports in an EtherChannel. • An EtherChannel will not form if one of the ports is a SPAN destination port. • An EtherChannel will not form if protocol filtering is set differently on the ports. • Enable all ports in an EtherChannel. If you disable a 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. • With software release 6.3(1) and later releases, an EtherChannel is preserved even if it contains only one port. In software releases prior to 6.3(1), traffic was disrupted when you removed a 1-port channel from spanning tree and then added it to spanning tree as an individual port. Catalyst 6000 Family Software Configuration Guide-Releases 6.3 and 6.4 6-4 78-13315-02