ISL Trunking is Cisco Proprieitary and is the perfered
method if used within a completely Cisco switched
fabric. 802.1q is the IEEE standard trunking
protocol.
The difference between the 2 is this ...
ISL actually encapsulates the frames traversing the
Trunk, which is to say it packages the VLAN
information within another packet extending the frame
size to 1522 and in a Cisco Switched Fabric, reacts
faster than 802.1q because it does not carry the same
load enabling 802.1q to be a standard trunking
protocol.
802.1q simply adds information to the existing frame
as it travels through the trunk. You would use 802.1q
if you had a mixed vendor switched fabric.
HTH
--- "Lopez, Robert" <[EMAIL PROTECTED]> wrote:
>
> What are the differences between isl and 802.1q
> trunking. If I'm in a total
> cisco switched environment, should I always use
> isl? What would be a good
> reason to use 802.1q? Which one is more favored
> over the other?
>
> Robert
>
>
>
> Robert M. Lopez
> Network Planning
> Ann Arbor Data Center
> Pfizer Global Research & Development
>
>
>
> _________________________________
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=====
Chris from Chicago
MasterCNE, 5.x CNE, ICNE, 4.x CNE, CCNA, MCP
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