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New Member

Encapsulation

Hi,

Can anyone tell me which encapsulation is best for trunking (isl or 802.1q) and why?

thanks in advance

Silju

5 REPLIES
New Member

Re: Encapsulation

ISL is used between CISCO and CISCO

dot1q can be used with CISCO and CISCO or CISCO to anybody else who supports it.

ISL tags all vlans packets

Dot1q tags all vlans packets except native vlan.

There is no preference if you just going to use it for trunking vlans between two switches. It is not really significantly different.

New Member

Re: Encapsulation

Thanks Siva,

But I came across a document that Cisco recommends dot1q although isl is cisco proprietery.

New Member

Re: Encapsulation

if you have the document, let us know.

as i said, if it is just simple trunk, it doesn't matter. this is my personal opinion ofcourse.

Re: Encapsulation

I think there are two reasons for using 802.1q:

a) as you said 802.1q is a standard, ISL is proprietary

b) compare the header length (3 bytes versus 26 bytes, if remember correctly - ISL has many header fields which are useless)

Regards,

Milan

New Member

Re: Encapsulation

I think that 802.1q is better (better?) than isl, because it modifies layer 2 headers, and don't add a new header, and isl do... the freame will be less heavy...

Regards...

omarg

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