11-7
Port-Based Virtual LANs (VLANs) and GVRP
Port-Based Virtual LANs (Static VLANs)
The Primary VLAN
Because certain features and management functions, such as single IP-
address stacking, run on only one VLAN in the switch, and because DHCP and
Bootp can run per-VLAN, there is a need for a dedicated VLAN to manage these
features and ensure that multiple instances of DHCP or Bootp on different
VLANs do not result in conflicting configuration values for the switch. The
primary VLAN is the VLAN the switch uses to run and manage these features
and data. In the factory-default configuration, the switch designates the
default VLAN (DEFAULT_VLAN) as the primary VLAN. However, to provide
more control in your network, you can designate another VLAN as primary.
To summarize, designating a non-default VLAN as primary means that:
■ The stacking feature runs on the switch’s designated primary VLAN
instead of the default VLAN
■ The switch reads DHCP responses on the primary VLAN instead of on the
default VLAN. (This includes such DHCP-resolved parameters as the
TimeP server address, Default TTL, and IP addressing—including the
Gateway IP address—when the switch configuration specifies DHCP as
the source for these values.)
■ The default VLAN continues to operate as a standard VLAN (except, as
noted above, you cannot delete it or change its VID).
■ Any ports not specifically assigned to another VLAN will remain assigned
to the Default VLAN, regardless of whether it is the primary VLAN.
Candidates for primary VLAN include any static VLAN currently configured
on the switch. (A dynamic—GVRP-learned—VLAN that has not been con-
verted to a static VLAN cannot be the primary VLAN.) To display the current
primary VLAN, use the CLI show vlan command.
Note If you configure a non-default VLAN as the primary VLAN, you cannot delete
that VLAN unless you first select a different VLAN to act as primary.
If you manually configure a gateway on the switch, it will ignore any gateway
address received via DHCP or Bootp.
!Software.book Page 7 Thursday, October 10, 2002 6:10 PM
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