HP TopTools for Hubs and Switches - Manual (Page 176)

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Managing Switches
Configuring Switch Features
Stack Management with VLANs
You can use stacks in a VLAN environment. Each switch in the stack
(Commander and Members) uses only the default VLAN configured in that
switch for stack links. In the Web browser interface, this is the VLAN labeled
Default <VLAN ID>. All VLANs in the stack need to be interconnected through
the default VLAN.
The VLAN ID for the default VLAN must be the same for all switches in the
stack. The default VLAN name can differ among switches in the stack. For
example, if the VLAN ID (VID) for the default VLAN in Switch A is “1” and the
default VID for Commander Switch B is “5”, then Switch A can't be a Candidate
or a Member of Commander Switch B's stack, even though you may have
connectivity to Switch A from Commander Switch B through other tagged
VLANs.
Benefits of Stack Management
Stacking benefits include:
■ Reducing the number of IP addresses required for managing your
switches
■ Increasing the scalability of your network to handle more traffic when
used with switch meshing
■ Simplifying network management for small groups
See the online help for more information about stack management.
VLAN Configuration
VLANs are a method for segmenting a network into related groups, improving
the efficiency of traffic flow and limiting the propagation of multicast and
broadcast messages. Traffic between VLANs is blocked unless the VLANs are
connected by a router, increasing security.
A VLAN is a group of ports designated by the switch as belonging to the same
broadcast domain. That is, all ports carrying traffic for a particular subnet
address would belong to the same VLAN. Using a VLAN, you can group users
by logical function instead of physical location. This helps to control band-
width usage by allowing you to group high-bandwidth users on low-traffic
segments and to organize users from different LAN segments according to
their need for common resources. Beginning with release C.06.01 of the switch
software (operating system, or “OS”) you can use the switch's console inter-
face to configure up to 30 port-based, IEEE 802.1Q-compliant VLANs. (Earlier
releases of the OS allow up to eight port-based, IEEE 802.1Q-compliant
VLANs.) This enables you to use the same port for two or more VLANs and
still allows interoperation with older switches that require a separate port for
each VLAN.
The benefits of VLANs include:
■ Grouping users into logical networks for increased performance