Blade ICE G8000 - Manual (Page 78)

RackSwitch G8000 Application Guide
78 „ Chapter 5: Spanning Tree BMD00041, November 2008
Creating a VLAN
When you create a VLAN, that VLAN automatically belongs to STG 1, the default STG.
You can assign the VLAN to another STG.
„ Move a newly created VLAN to an existing STG by following this order:
† Create the VLAN.
† Enable the VLAN.
† Add the VLAN to an existing STG.
„ 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 tagged ports can belong to multiple STGs.
„ A port cannot be added directly to an STG. First add the port to a VLAN, then add the
VLAN to the STG.
Rules for VLAN Tagged ports
„
Tagged ports can belong to more than one STG.
„ Untagged ports can belong to only one STG.
Adding and removing ports from STGs
„
When you add a port to a VLAN that belongs to an STG, the VLAN’s member port is
added to the STG. However, if the port you are adding is an untagged port and is already a
member of an STG, that port will be removed from this STG and added to the new STG.
An untagged port cannot belong to more that one STG.
For example, assume that VLAN 2 belongs to STG 2. You add an untagged port (port 5)
that belongs to STG 2 to VLAN 2. The port becomes a member of STG 2, and the switch
displays a message to inform you that the PVID changed from 1 to 2:
„ When you remove a port from a VLAN that belongs to an STG, that port is removed from
the STG. However, if that port belongs to another VLAN in the same STG, the port
remains in the STG.
"Port 5 is an UNTAGGED port and its PVID changed from 1 to 2.