ISL and 802.1q on the Same Core Switch

Answered Question
Jul 11th, 2003
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I currently use ISL for trunking in our LAN. We are in the process of swapping out our closet switches and I wanted to start using 802.1q. This migration will not be done all at once so I'm concerned whether you can have a core switch connecting some switches via ISL and others via 802.1q. I also have a Foundry switch that we use for load balancing that will require 802.1q as well.


My current core switch is a Catalyst 6509 running Native IOS v12.1(12c)E2


Thanks in advance,

Mike

Correct Answer by Prashanth Krishnappa about 14 years 1 month ago

Ofcourse...The CLI will let you have only one encapsulation on any physical interface at any given instance of time:-)

Correct Answer by konigl about 14 years 1 month ago

Just not both on the same VLAN trunk port at the same time. Each trunk port must be either ISL or 802.1q.

Correct Answer by Prashanth Krishnappa about 14 years 1 month ago

You sure can have both ISL and dot1q trunks on the same switch

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Correct Answer
Prashanth Krishnappa Fri, 07/11/2003 - 12:39
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You sure can have both ISL and dot1q trunks on the same switch

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konigl Fri, 07/11/2003 - 19:41
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Just not both on the same VLAN trunk port at the same time. Each trunk port must be either ISL or 802.1q.

Correct Answer
Prashanth Krishnappa Sat, 07/12/2003 - 06:58
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Ofcourse...The CLI will let you have only one encapsulation on any physical interface at any given instance of time:-)

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