ProLiant BL e-Class C-GbE Interconnect Switch Web-based Interface Reference Guide

Configuring the Switch Modules using the Web-based Interface
The configuration of the lowest numbered port in the group becomes the configuration for all
of the ports in the trunk group. This port is called the master port of the trunk group, and all
configuration options, including the VLAN configuration, which can be applied to the master
port, are applied to the entire port trunking group.
Load balancing is automatically applied to the ports in the trunked group, based on the setting
of the trunk load-sharing algorithm, and a link failure within the group causes the network
traffic to be directed to the remaining links in the group.
Spanning Tree Protocol treats a port trunking group as a single link on the switch module
level. STP uses the port parameters of the master port in the calculation of port cost and in
determining the state of the port trunking group. If two redundant port trunking groups are
configured on the switch module, STP blocks one entire group, similar to STP blocking a link
in case of two redundant links.
Considerations when Creating a Port Trunking Group
When creating a port trunking group, consider the following rules that determine how the port
trunk reacts in network topology:
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The first port of the port trunk is implicitly configured to be the master logical port. This
is the reference port used in configuration commands. It can be thought of as the logical
port representing the entire port group.
When using a port trunk, always reference the master logical port of the group when
configuring or viewing VLANs.
VLANs configured to use other ports in the port trunk will have those ports deleted from
the VLAN when the port trunk becomes enabled.
The Spanning Tree algorithm views port trunk as a single Spanning Tree port. The
Spanning Tree port is represented by the master logical port.
If the VLAN settings of the master logical port are changed, the VLAN settings of all
members of that port trunk are changed similarly.
If the IGMP snooping configuration for any port trunk member is changed, the IGMP
snooping settings for all port trunk members are changed.
The port trunk takes precedence over any other setting. That is, the settings of trunked
ports are the same as the master port settings.
When any trunked port becomes a non-trunked port, all of the port configurations are
reset to default settings.
Refer to Appendix G in the HP ProLiant e-Class C-GbE Interconnect Switch User Guide for
additional information on port trunking.
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