General Guidelines - 3Com corebuilder 3500 Implementation Manual

General Guidelines

The VLAN mode of allOpen or allClosed applies to all VLANs
associated with the system (static, dynamic, or router port). Configure
the VLAN mode before you define any static VLANs. (As part of the
configuration procedures for a router port IP interface, you must place
the system in allClosed mode; see Chapter 11.)
If you change the VLAN mode after you have defined VLANs, the system
deletes all configured VLANs and redefines the default VLAN. See
"Modifying the VLAN Mode" later in this chapter.
If you configure the system for allClosed mode, you can enable Ignore
STP mode on any VLAN. You can also disable STP on a any port for
either allOpen or allClosed mode by using a bridge port option. (Use
bridge port stpState
Chapter 7 for bridging information. Also see "Ignore STP Mode" later
in this chapter.
To take advantage of GVRP for dynamic configuration or dynamic
updates of port-based VLANs, verify that GVRP is enabled as both a
bridge-wide and a bridge-port parameter. See Chapter 9 for
information about bridging parameters. See "Dynamic Port-based
VLANs Using GVRP" for information about GVRP.
You can configure overlapping VLANs if they have some distinguishing
characteristic. For example, a bridge port can be shared by multiple
VLANs as long as the shared port has a distinguishing characteristic for
the shared port, such as protocol type or tagging type. In allClosed
mode, you must tag overlapped ports of any network-based VLANs.
See "Network-based IP VLANs" later in this chapter.
Per-port tagging requirements depend on whether the hosts
connected to the port are configured for IEEE 802.1Q tagging.
Per-port tagging is also required to differentiate between overlapped
ports of the same protocol type and between overlapped IP Layer 3
VLANs in allClosed mode.
Consider maintaining the system's default VLAN. The default VLAN
preserves the flooding of unspecified traffic, since it initially contains
all of the system's bridge ports, with unspecified protocol information
and no tagging.
Key Guidelines for Implementation
on the Administration Console.) See
167