BLADE OS™ Application Guide HP GbE2c Ethernet Blade Switch for c-Class BladeSystem Version 5.1 Advanced Functionality Software

Table Of Contents
BLADE OS 5.1 Application Guide
BMD00113, September 2009 Chapter 5: Spanning Tree Protocol 113
When creating a VLAN, also consider the following:
VLANs must be contained within a single STG; a VLAN cannot span multiple STGs. By
confining VLANs within a single STG, you avoid problems with spanning tree blocking ports
and causing a loss of connectivity within the VLAN. When a VLAN spans multiple switches, it
is recommended that the VLAN remain within the same Spanning Tree Group (have the same
STG ID) across all the switches.
If ports are tagged, all trunked ports can belong to multiple STGs.
A port that is not a member of any VLAN cannot be added to any STG. The port must be added
to a VLAN, and that VLAN added to the desired STG.
Rules for VLAN Tagged Ports
Rules for VLAN tagged ports are listed below:
If a port is tagged, it can belong to multiple STGs.
When a tagged port belongs to more than one STG, the egress BPDUs are tagged to distinguish
the BPDUs of one STG from those of another STG.
An untagged port cannot span multiple STGs.
Adding and Removing Ports from STGs
Information on adding and removing ports from STGs is as follows:
By default, all ports belong to VLAN 1 and STG 1 (except management port 19).
Each port is always a member of at least one VLAN. Each VLAN is always a member of at
least one STG. Port membership within VLANs can be changed, and VLAN membership
within STGs can be changed. To move a port from one STG to another, move the VLAN to
which the port belongs, or move the port to a VLAN that belongs to the STG.
When you remove a port from a VLAN, that port is also removed from the STG to which the
VLAN belongs. However, if that port belongs to another VLAN in the same STG, the port
remains in the STG.
If you remove an untagged port from a non-default VLAN and STG, it is added to VLAN 1 and
STG 1.