Technical data

BLADE OS 5.1 Application Guide
BMD00136, November 2009 Chapter 4: Ports and Trunking
 67
Static Trunk Group Configuration Rules
The trunking (portchannel) 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.
 Any physical switch port can belong to only one trunk group.
 Trunking from third-party devices must comply with Cisco
®
EtherChannel
®
technology.
 All trunk member ports must be assigned to the same VLAN configuration before the trunk can
be enabled.
 When an active port is configured in a trunk, the port becomes a trunk member when you
enable the trunk. 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 (STG) and can belong to only
one Spanning Tree Group (STG). However if all ports are tagged, then all trunk ports can
belong to multiple STGs.
 If you change the Spanning Tree participation of any trunk member to enabled or
disabled, the Spanning Tree participation of all trunk members changes similarly.
 When a trunk is enabled, the trunk’s 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.
 Trunks cannot be monitored by a monitor port; however, trunk members can be monitored.
 All ports in static trunks must be have the same link configuration (speed, duplex, flow
control).