Before you configure trunks
When you create and enable a trunk, the trunk members (switch ports) take on certain settings necessary
for correct operation of the trunking feature.
Before you configure your trunk, you must consider these settings, along with specific configuration rules,
Read the configuration rules provided in the "Trunk group configuration rules" section.
Determine which switch ports (up to six) are to become trunk members (the specific ports making up
Ensure that the chosen switch ports are set to enabled, using the following command: /cfg/port
Trunk member ports must have the same VLAN configuration.
Consider how the existing spanning tree will react to the new trunk configuration. See the "Spanning
Tree Protocol" chapter for spanning tree group configuration guidelines.
Consider how existing VLANs will be affected by the addition of a trunk.
Trunk group configuration rules
The trunking feature operates according to specific configuration rules. When creating trunks, consider
the following rules that determine how a trunk group reacts in any network topology:
All trunks must originate from one device, and lead to one destination device. For example, you
cannot combine a link from Server 1 and a link from Server 2 into one trunk group.
Any physical switch port can belong to only one trunk group.
Trunking from non-HP devices must comply with Cisco® EtherChannel® technology.
All trunk member ports must be assigned to the same VLAN configuration before the trunk can be
All trunk member ports must be set to full duplex mode.
All trunk member ports must be configured for the same speed.
If you change the VLAN settings of any trunk member, you cannot apply the change until you
change the VLAN settings of all trunk members.
When an active port is configured in a trunk, the port becomes a trunk member when you enable the
trunk using the /cfg/l2/trunk x/ena command. The spanning tree parameters for the port then
change to reflect the new trunk settings.
All trunk members must be in the same spanning tree group and can belong to only one spanning
tree group. However if all ports are tagged, then all trunk ports can belong to multiple spanning tree
When a trunk is enabled, the trunk spanning tree participation setting takes precedence over that of
any trunk member.
You cannot configure a trunk member as a monitor port in a Port Mirroring configuration.
A monitor port cannot monitor trunks; however, trunk members can be monitored.
Ports and trunking