From: Yu (kyshum@gmail.com)
Date: Thu Apr 27 2006 - 06:31:56 GMT-3
Hi Group,
capture from cisco: (
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_8_1/confg_gd/v
lans.htm#wp1090780
)
==================================================================
Mapping 802.1Q VLANs to ISL VLANs
Your network might have non-Cisco devices that are connected to the
Catalyst 6500 series switches through 802.1Q trunks or traffic from a
non-Cisco switch that has VLANs in the Catalyst 6500 series reserved range,
1002-1024.
The valid range of user-configured Inter-Switch Link (ISL) VLANs is 1-1000
(and 1002-1005; see Table 11-1 <vlans.htm#wp1090780>) and 1025-4094. The
valid range of VLANs that are specified in the IEEE 802.1Q standard is
0-4095. In a network environment with non-Cisco devices that are connected
to Cisco switches through 802.1Q trunks, you can map 802.1Q VLAN numbers
that are greater than 1000 to ISL VLAN numbers. Note that 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.
802.1Q VLANs in the range 1-1000 are automatically mapped to the
corresponding ISL VLAN. 802.1Q VLAN numbers greater than 1000 must be mapped
to an ISL VLAN in order to be recognized and forwarded by Cisco switches.
These restrictions apply when mapping 802.1Q VLANs to ISL VLANs:
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 802.1Q VLANs to 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, 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, traffic on 802.1Q VLAN 200 is blocked.
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:
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*
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*
802.1q vlan 2000 is existent in the mapping table
Console> (enable) *set vlan mapping dot1q 3000 isl 300
*
Vlan mapping successful
Console> (enable) *set vlan mapping dot1q 4000 isl 400
*
Vlan mapping successful
Console> (enable) *show vlan mapping
*
802.1q vlan ISL vlan Effective
------------------------------------------
2000 200 true
3000 300 true
4000 400 true
Console> (enable)
==================================================================
I had read it many times, but I think I do not quite understand that WHEN
this feature is useful. From my understanding, there is no need to do any
mapping if a cat6500 have both ISL and dot1Q trunk.
Do anyone knows under what kind of situation that we need to use this
feature?
Thanks in advance!
This archive was generated by hypermail 2.1.4 : Mon May 01 2006 - 11:41:59 GMT-3