Cisco Systems Configuring VLAN Subinterfaces and 802.1Q Trunking

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Cisco ASA 5500 Series Configuration Guide using ASDM
Chapter12 Starting Interface Configuration (ASA 5510 and Higher)
Starting Interface Configuration (ASA 5510 and Higher)
Step8 Click Apply.
Step9 To set the LACP system priority, perform the following steps. If the device at the other end of the
EtherChannel has conflicting port priorities, the system priority is used to determine which port
priorities to use. See Step 6d for more information.
a. Depending on your context mode:
•For single mode, choose the Configuration > Device Setup > EtherChannel pane.
•For multiple mode in the System execution space, choose the Configuration > Context
Management > EtherChannel pane.
b. In the LACP System Priority field, enter a priority between 1 and 65535.
The default is 32768.
What to Do Next
Optional Task:
•Configure VLAN subinterfaces. See the “Configuring VLAN Subinterfaces and 802.1Q Trunking”
section on page 12-35.
Required Tasks:
•For multiple context mode, assign interfaces to contexts and automatically assign unique MAC
addresses to context interfaces. See the “Configuring Multiple Contexts” section on page11-14.
•For single context mode, complete the interface configuration. See the Chapter14, “Completing
Interface Configuration (RoutedMode),” or Chapter 15, “Completing Interface Configuration
(TransparentMode, 8.4 and Later).”
Configuring VLAN Subinterfaces and 802.1Q Trunking
Subinterfaces let you divide a physical, redundant, or EtherChannel interface into multiple logical
interfaces that are tagged with different VLAN IDs. An interface with one or more VLAN subinterfaces
is automatically configured as an 802.1Q trunk. Because VLANs allow you to keep traffic separate on a
given physical interface, you can increase the number of interfaces available to your network without
adding additional physical interfaces or ASAs. This feature is particularly useful in multiple context
mode so that you can assign unique interfaces to each context.
Guidelines and Limitations
•Maximum subinterfaces—To determine how many VLAN subinterfaces are allowed for your
platform, see the “Licensing Requirements for ASA 5510 and Higher Interfaces” section on
page 12-8.
•Preventing untagged packets on the physical interface—If you use subinterfaces, you typically do
not also want the physical interface to pass traffic, because the physical interface passes untagged
packets. This property is also true for the active physical interface in a redundant interface pair.