11-9
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 11 Configuring VLANs
Mapping VLANs to VLANs
Mapping 802.1Q VLANs to ISL VLANs
Your network might have non-Cisco devices that are connected to the Catalyst 6500 series switches
through the 802.1Q trunks.
The valid range of the user-configured Inter-Switch Link (ISL) VLANs is 1–1000 (and 1002–1005) and
1025–4094. The valid range of VLANs that is specified in the IEEE 802.1Q standard is 0–4095. In a
network environment with the non-Cisco devices that are connected to the Cisco switches through the
802.1Q trunks, you can map the 802.1Q VLAN numbers that are greater than 1000 to the ISL VLAN
numbers. If you use any VLANs in the extended range (1025–4094) for dot1q mappings, you cannot use
any of the extended-range VLANs for any other purpose.
The 802.1Q VLANs in the range 1–1000 are automatically mapped to the corresponding ISL VLAN.
The 802.1Q VLAN numbers greater than 1000 must be mapped to an ISL VLAN in order to be
recognized and forwarded by the Cisco switches.
These restrictions apply when mapping the 802.1Q VLANs to the ISL VLANs:
•
The global VLAN mapping feature and the per-port/per-ASIC VLAN mapping features (see the
“Configuring VLAN Mappings on a Per-Port or Per-ASIC Basis” section on page 11-14
) are
mutually exclusive; only one feature can be enabled at any time.
•
If there are any extended-range VLANs present on the switch, you cannot map any new 802.1Q
VLANs-to-ISL VLANs.
•
You can configure up to eight 802.1Q-to-ISL VLAN mappings on the switch.
•
You can only map the 802.1Q VLANs to the Ethernet-type ISL VLANs.
•
Do not enter the native VLAN of any 802.1Q trunk in the mapping table.
•
When you map an 802.1Q VLAN to an ISL VLAN, the traffic on the 802.1Q VLAN corresponding
to the mapped ISL VLAN is blocked. For example, if you map 802.1Q VLAN 2000 to ISL
VLAN 200, the traffic on 802.1Q VLAN 200 is blocked.
•
The VLAN mappings are local to each switch. Make sure that you configure the same VLAN
mappings on all appropriate switches in the network.
To map an 802.1Q VLAN to an ISL VLAN, perform this task in privileged mode:
This example shows how to map 802.1Q VLANs 2000, 3000, and 4000 to ISL VLANs 200, 300, and
400, and verify the configuration:
Console> (enable)
set vlan mapping dot1q 2000 isl 200
Vlan mapping successful
Console> (enable)
set vlan mapping dot1q 3000 isl 300
Vlan mapping successful
Task
Command
Step 1
Map an 802.1Q VLAN to an ISL Ethernet VLAN. The
valid range for
dot1q_vlan
is 1001–4095. The valid
range for
isl_vlan
is 1–1000.
set vlan mapping dot1q
dot1q_vlan
isl
isl_vlan
Step 2
Verify the VLAN mapping.
show vlan mapping