2-34
Static Virtual LANs (VLANs)
Port-Based Virtual LANs (Static VLANs)
■ During a Telnet session to the switch, if you configure the Management-
VLAN to a VID that excludes the port through which you are connected
to the switch, you will continue to have access only until you terminate
the session by logging out or rebooting the switch.
■ During a web browser session to the switch, if you configure the Manage-
ment-VLAN to a VID that excludes the port through which you are
connected to the switch, you will continue to have access only until you
close the browser session or rebooting the switch.
Note The Management-VLAN feature does not control management access through
a direct connection to the switch’s serial port.
■ Enabling Spanning Tree where there are multiple links using separate
VLANs, including the Management VLAN, between a pair of switches,
Spanning Tree 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.
Figure 2-25. Example of Inadvertently Blocking a Management VLAN Link by
Implementing Spanning Tree
Effect of VLANs on Other Switch Features
Spanning Tree Operation with VLANs
Because the switch follows the 802.1Q VLAN recommendation to use single-
instance spanning tree, Spanning Tree operates across all ports on the switch
(regardless of VLAN assignments) instead of on a per-VLAN basis. This means
that if redundant physical links exist between the switch and another 802.1Q
device, all but one link will be blocked, regardless of whether the redundant
VLAN 20 (Management VLAN)
VLAN 1
VLAN 40
Switch
1
Switch
2
Even though the ports on the Management VLAN link between Switch 1 and Switch 2 do not belong
to the other VLANs connecting the two switches, enabling Spanning Tree will block one of the two
links. This is because Spanning Tree operates per-switch and not per-VLAN.
VLAN 1
VLAN 40
VLAN 20 Only
(Management VLAN)
Blocked
To Next Page
Loading...
Need help?
General
