3Com OfficeConnect WX1200, Reference Manual

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212 C
HAPTER
6: C
ONFIGURING
WX S
YSTEM
P
ARAMETERS
6 To tag a port or port group, select the Tag checkbox.
If you specify a tag value, 3Com recommends that you use the same value
as the VLAN number. 3Com switches do not require the VLAN number and
tag value to be the same, but some other vendors’ devices do.
7 To change a tag value, change the number in the Tag Value field.
By default, a port or port group’s tag value is the same as the VLAN ID.
8 Click OK .
Changing VLAN
Spanning Tree
Settings
The purpose of the Spanning Tree Protocol (STP) is to maintain a loop-free
network. A loop-free path is accomplished when a device recognizes a loop
in the topology and blocks one or more redundant paths.
Mobility System Software (MSS) supports 802.1D and Per-VLAN
Spanning Tree protocol (PVST+).
„
MSS uses 802.1D bridge protocol data units (BPDUs) on VLAN ports
that are untagged. However, each VLAN still runs its own instance of
STP, even if two or more VLANs contain untagged ports. To run a
single instance of STP in 802.1D mode on the entire switch, configure
all network ports as untagged members of the same VLAN.
„
MSS uses PVST+ BPDUs on VLAN ports that are tagged. PVST+ BPDUs
include tag information in the 802.1Q field of the BPDUs. MSS runs a
separate instance of PVST+ on each tagged VLAN.
When you create a VLAN, STP is disabled on the new VLAN by default,
regardless of the STP state of other VLANs on the WX switch.
The IEEE 802.1D spanning tree specifications refer to networking devices
that forward Layer 2 traffic as bridges. In this context, a WX switch is a
bridge. Where this manual or the product interface uses the term bridge,
you can assume the term is applicable to the WX switch.
To change a VLAN’s STP settings:
1 Access the VLAN table:
a Select the Configuration tool bar option.
b In the Organizer panel, click the plus sign next to the WX switch.
c Click the plus sign next to System.
d Select VLANs .