From: anthony.sequeira@thomson.com
Date: Wed Jan 17 2007 - 11:33:33 ART
The VLAN mapping feature is for integrating two networks - one that is
using ISL and one that is using 802.1Q.
The reason that this feature is needed is that ISL does not support as
broad a range of VLAN IDSs (VID) as 802.1Q does. In 802.1Q - the VLAN
range is 1 to 4094. In ISL - the range is 1 to 1024.
So the problem comes when you have 802.1Q VLANs numbered - let's say -
1100, 1200, and 1300. These VLANs must be mapped to VIDs in the ISL
range if they are to be integrated into the ISL-based network. Please
note again that ISL has no way to deal with VLANs numbered this high!
To avoid this issue altogether, it is recommend that you never number
your 802.1Q VLANs outside the ISL range. Now, mapping is unnecessary, as
"802.1Q VLANs in the range 1-1000 are automatically mapped to the
corresponding ISL VLAN". Please note that having close to 1000 VIDs to
pick from should be more than sufficient for any network - no matter how
complex!
I hope this helps and is what you needed.
Anthony J. Sequeira
#15626
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Hash Aminu
Sent: Wednesday, January 17, 2007 2:34 AM
To: Durkin, Michael (MED US)
Cc: johngibson1541@yahoo.com; ccielab@groupstudy.com
Subject: Re: Mapping 802.1Q VLANs to ISL VLANs
Hello,
thank you for your response, i am not asking for the theory of how the
frames are built,.
there is a feature in IOS to map ISL and .1Q VLANs you may checkout this
link .
may be u can understand it quicker than me and explain.
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_5_4/confi
g/vlans.htm#wp26939
thank you
Hash
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