inside vlan

[kozorezdi]

Hello everybody!

I have a small discussion with my colleagues about operation with Access interfaces on a Switch.

I have an opinion that when you created a vlan 10, you've gotten STP instance and CAM per vlan.

When a frame from a host comes on one Access Port Vlan 10, on income to vlan NO adding any 802.1Q tag.

If a frame goes to other Access Port inside of Vlan 10 it will go out also without any tag.

During such operations inside local vlan no tagging at all.

802.1Q tag will be added on non-native vlan on out of a trunk port 802.1Q and on another side the tag will be removed and the frame goes inside vlan 10 and to the destination port.

I suppose inside vlan we don't have any 802.1q or ISL, we have gotten this situation only on a trunk.

Am I right?  Thank you in advance for help!

P.S. we are not talking about incoming frame on an access port with a tag/double tagging/vlan hopping...

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Best regards,

Dmitry

[petenixon · Accepted solution]

If i have understood your question correctly, yes. Frames that are destined to an interface on the same switch (and in the same vlan) will not be tagged. Frames destined outside the vlan (to another vlan) or require the switch to forward over a trunk will be tagged.

[kozorezdi]

Hi,

Thank you for reply!  Yes, it is what I am trying to ask ;)

  Another words, we can say that tagging 802.1q is used only on Trunk Ports and it has no relation to the operations inside one vlan (in/out via Access Ports). 

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Dmitry

[petenixon]

Yes that's correct!

[kozorezdi]

I can't agree more ;)  Thanks a lot!

I have found the explanation about it inside of a book of Todd Lammle.  It is the final argument ;)

"An access port belongs to and carries the traffic of only one VLAN. Traffic is
both received and sent in native formats with no VLAN information (tagging) whatsoever.
Anything arriving on an access port is simply assumed to belong to the VLAN assigned to the port. Because an access port doesn’t look at the source address, tagged traffic—a frame with added VLAN information—can be correctly forwarded and received only on trunk ports."

Thank you very much!

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Dmitry