Port Grouping (EtherChannel)

With the Port Grouping (EtherChannel) window, you can:

• Create Fast EtherChannel and Gigabit EtherChannel port groups.
• Remove ports from a port group.
• Change the forwarding method for a group.

Fast EtherChannel and Gigabit EtherChannel port groups are logical high-speed connections between switches or between switches and servers. Port groups can also provide redundant links between switches. The switch treats the port group as a single logical port; therefore, when you create a port group, the switch uses the configuration of the first port for all ports added to the group. After the group is created, changing STP or VLAN membership parameters for one port in the group automatically changes the parameters for all ports.

One port in each group carries all unknown multicast, broadcast, and STP packets.

Port Group Restrictions

Any port except an ATM port can belong to a port group, but the following restrictions apply:

• No port group member can be configured for port monitoring.
• No port group member can be enabled for port security.
• Port group members must belong to the same set of VLANs and must be either all static-access, all multi-VLAN, or all trunk ports.
• Dynamic-access ports cannot be grouped with any other port, not even with other dynamic-access ports.
• A network port cannot be in a destination-based port group.

Creating a Port Group

You can create up to 12 port groups. Ports within a group must be either all source-based or all destination-based ports. You can create source-based and destination-based groups on the same switch.

A source-based port group can contain up to eight members. A destination-based port group can contain an unlimited number of members. By default, all port groups are configured for source-based forwarding.

Note: Review Port Group Restrictions before you use this procedure.

To configure a port group:

1. From the Port Grouping window, select the row containing only a port group number.
2. Cick Modify to display the Port Group Configuration dialog box.
3. From the Available Ports list, select the ports for the group.
   To select several ports, hold down the Ctrl key and make your selections; or, hold down the Shift key and select the first and last port in a range.
4. Click Add to move the port to the Selected Ports list.
   To remove a port from the Selected Ports list, select the port and click Remove. The port is returned to the end of the Available Ports list.
5. In the Forwarding Method section, select the Source-based (the default) or Destination-based checkbox to specify the forwarding method.
   The forwarding method applies to all ports in the port group.
6. Click OK to put your changes in effect and close the Port Group Configuration dialog box.
   The new group is displayed on the Port Grouping window.
7. Click OK to close the Port Group window.

Note: By default, a switch forwards traffic to a port group based on the packet source address. If you configure a static address for a port group, configure the switch to forward packets from the static address to all ports in the group to eliminate the chance of lost packets. If you set the port group to forward packets based on the destination address, configure the switch to forward packets destined for the static address to only one port in the port group. Otherwise, the destination address will receive duplicate packets.

Removing Ports from a Port Group

To remove a port from a port group:

1. From the Port Grouping window, select the row containing the port group number.
2. Cick Modify to display the Port Group Configuration dialog box.
3. From the Selected Ports list, select the ports that you want to remove.
   To select several ports, hold down the Ctrl key and make your selections; or, hold down the Shift key and select the first and last port in a range.
4. Click Remove to remove the ports from the Selected Ports list.
   Note: When you remove a port from the group, you must remove it from both ends of the link. The ports are returned to the end of the Available Ports list.
5. Click OK to put your changes in effect and close the Port Group Configuration dialog box.
6. Click OK to close the Port Group window.

Changing the Forwarding Method for a Group

To change the distribution for a group:

1. From the Port Grouping window, select the row containing the number of the port group to change.
2. Click Modify to display the modification dialog box.
3. In the Forwarding Method section, select the Source-based or Destination-based checkbox to make your change.
4. Click OK to put your changes in effect and close the Port Group Configuration dialog box.
   The new forwarding method is displayed on the Port Grouping window.
5. Click OK to close the Port Group window.