KB.15.15

• Enabling Spanning Tree between a pair of switches where there are multiple links using

separate VLANs, including the Management VLAN, will force the blocking of one or more

links. This may include the link carrying the Management VLAN, which will cause loss of

management access to some devices. This can also occur where meshing is configured and

the Management VLAN is configured on a separate link.

• Monitoring Shared Resources: The Management VLAN feature shares internal switch resources

with several other features. The switch provides ample resources for all features. However, if

the internal resources become fully subscribed, the Management VLAN feature cannot be

configured until the necessary resources are released from other uses. For information on

determining the current resource availability and usage, see the Management and Configuration

Guide for your switch.

Example 47 Inadvertently blocking a Management VLAN link by implementing spanning tree

Voice VLANs

Configuring voice VLANs separates voice traffic from data traffic and shields your voice traffic

from broadcast storms.

Operating rules for voice VLANs

• You must statically configure voice VLANs. GVRP and dynamic VLANs do not support voice

VLAN operation.

• Configure all ports in a voice VLAN as tagged members of the VLAN. This ensures retention

of the QoS (Quality of Service) priority included in voice VLAN traffic moving through your

network.

• If a telephone connected to a voice VLAN includes a data port used for connecting other

networked devices (such as PCs) to the network, then you must configure the port as a tagged

member of the voice VLAN and a tagged or untagged member of the data VLAN you want

the other networked device to use.

Components of voice VLAN operation

• Voice VLAN: Configure one or more voice VLANs on the switch. Some reasons for having

multiple voice VLANs include:

• Employing telephones with different VLAN requirements

• Better control of bandwidth usage

• Segregating telephone groups used for different, exclusive purposes

60 Static Virtual LANs