Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
New Member

Do ISL trunking supports Native vlan?

Hi all,

i know 802.1q trunking supports native lan but need to make sure that if ISL trunking  supports native vlan or  not?

thanks

mahesh

2 ACCEPTED SOLUTIONS

Accepted Solutions
Hall of Fame Super Silver

Re: Do ISL trunking supports Native vlan?

Hello Mahesh,

ISL has no native vlan concept because it places the whole ethernet frame in the payload of an ISL frame

native Vlan is an 802.1Q specfic feature/concept

Hope to help

Giuseppe

Hall of Fame Super Blue

Re: Do ISL trunking supports Native vlan?

Mahesh

Just to add to Giuseppe's post -

ISL is Cisco proprietary unlike 802.1q. Because of this ISL does not need a native vlan because by definition you would need to have an all cisco network if you wanted to run ISL on your switches. So every switch would be capable of supporting PVST (Per vlan spanning tree). PVST is Cisco proprietary as well.

802.1q is an IEEE standard and because of this it needs to interoperate with switches that may not run PVST and hence the need for the native vlan ie. the vlan that is not tagged on a trunk link.

Jon

3 REPLIES
Hall of Fame Super Silver

Re: Do ISL trunking supports Native vlan?

Hello Mahesh,

ISL has no native vlan concept because it places the whole ethernet frame in the payload of an ISL frame

native Vlan is an 802.1Q specfic feature/concept

Hope to help

Giuseppe

New Member

Re: Do ISL trunking supports Native vlan?

Hi Jon and guislar,

Many thanks for reply

Mahesh

Hall of Fame Super Blue

Re: Do ISL trunking supports Native vlan?

Mahesh

Just to add to Giuseppe's post -

ISL is Cisco proprietary unlike 802.1q. Because of this ISL does not need a native vlan because by definition you would need to have an all cisco network if you wanted to run ISL on your switches. So every switch would be capable of supporting PVST (Per vlan spanning tree). PVST is Cisco proprietary as well.

802.1q is an IEEE standard and because of this it needs to interoperate with switches that may not run PVST and hence the need for the native vlan ie. the vlan that is not tagged on a trunk link.

Jon

3898
Views
0
Helpful
3
Replies
CreatePlease to create content