3Com 4007, Implementation Manual, Page: 254 / 684

254 C
HAPTER
14: V
IRTUAL
LAN
S
(VLAN
S
)
(Example: If the backplane and switch fabric module ports for the
default VLAN are untagged, the backplane and switch fabric module
ports for all other VLANs must be tagged.) It is safer to tag the
backplane and switch fabric module ports of
all VLANs, although in
some configurations, some overhead could be associated with
tagging.
Procedural Guidelines Follow these procedural guidelines to configure VLANs on the modules in
your system:
1 Use the EME to connect to each Layer 2 and Multilayer Switching Module
individually and configure the VLAN mode and VLANs for each module.
2 On each switching module, select the VLAN mode of allOpen or
allClosed.
3
On each switching module, create the appropriate number of VLANs for
your configuration. For each VLAN definition:
a Select a VID for the VLAN and provide information based on the type
of VLAN: port-based information for Layer 2 modules; port-based,
protocol-based, and network-based information for Multilayer
Switching Modules.
b
Include the appropriate front-panel ports. Tag the front-panel ports if
you need to (that is, if the ports overlap with another VLAN and
tagging is the only distinguishing characteristic). Remember that if you
tag a port, the attached device must support IEEE 802.1Q tagging. If
you are configuring a Multilayer Switching Module that serves as a
router, your VLAN may or may not include front-panel ports.
c Include the backplane port of the switching module in the VLAN
definition unless the VLAN traffic is limited to that switching module
only and will not pass through the switch fabric module. If the
switching module supports two backplane ports (and resides in a slot
that supports two switch fabric module ports), you typically configure
the lower-numbered backplane port. (Example: On a 10-port Layer 2
switching module, you configure port 11; on a 12-port Multilayer
Switching Module, you configure port 13.) When you have multiple
VLANs, tag the backplane port. (In a subsequent step, you must tag
the associated switch fabric module backplane port as well.)