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ISL and 802.1q on the Same Core Switch

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

3 ACCEPTED SOLUTIONS

Accepted Solutions
Cisco Employee

Re: ISL and 802.1q on the Same Core Switch

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

Gold

Re: ISL and 802.1q on the Same Core Switch

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

Cisco Employee

Re: ISL and 802.1q on the Same Core Switch

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

3 REPLIES
Cisco Employee

Re: ISL and 802.1q on the Same Core Switch

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

Gold

Re: ISL and 802.1q on the Same Core Switch

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

Cisco Employee

Re: ISL and 802.1q on the Same Core Switch

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

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