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jihed.neji Posted messages 11 Status Membre -  
ZePretender Posted messages 179 Status Membre -
Hello,

Can someone explain to me the difference between tagged and untagged !!
As simply as possible, I can't identify the difference between these two concepts
Who serves it and what is the difference between them!
Thank you

Configuration: Windows 7 / Firefox 18.0

4 réponses

Réponse 1 / 4
ZePretender Posted messages 179 Status Membre 34
 
Hello jihed.neji

This response was written by pbleue on May 11, 2005, at 12:08 PM

+------
When defining the ports associated with each VLAN, there are 3 modes: Untagged, Tagged, and No:

Untagged: The port is associated with only one VLAN. This means that any devices connected to this port will be part of the VLAN.

Tagged: Means that the frames arriving and leaving the port are marked with an additional 802.1q header in the Ethernet field.
A port can be "tagged" on multiple different VLANs.
The advantage of the Tagged mode is the ability to have a server communicating with all stations of the VLANs without the VLANs being able to communicate with each other.

No: No configuration in the VLAN.
-----+

PS: There is also the "Forbidden" mode

Hoping this helps you in your understanding.
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Réponse 2 / 4
salami411 Posted messages 128 Status Membre 6
 
Hello,

The term tagged is used in networking, particularly in the configuration of VLANs.

For inter-VLAN routing (via a level 3 switch, for example), the tag allows the switch to recognize which VLAN the tagged packet should be sent to. Tags thus enable (in this specific case) the identification of the VLAN of the destination of the transmitted packet.

Untagged, well, it means without a tag...
1
Réponse 3 / 4
ciscowarrior
 
attention, routing is a layer 3 concept and has nothing to do with dot1Q tags (802.1Q). these tags are used to differentiate which vlan the frames are destined for on a trunk (a link carrying traffic from multiple vlans); for this, the frames are marked (or tagged) with a vlan identifier.

alain
1
salami411 Posted messages 128 Status Membre 6
 
thank you for the clarification, Alain ;)
0
Réponse 4 / 4
jihed.neji Posted messages 11 Status Membre
 
Thank you for your response

I think I am gradually starting to understand the difference between these two modes.

Thank you
0
ZePretender Posted messages 179 Status Membre 34
 
jihed.neji

Explanation in my words ;o)

We set it to "untagged" when there is only one VLAN to configure on the switch port
We set it to "tagged" when there are two or more VLANs to configure on the same switch port.

This allows us to connect multiple networks on the same switch and "pass" these networks through a single port.

Ex:
Switch with 3 VLANs :
VLAN1= ID 1 (Office network)
VLAN2 = ID 2 (Production network A)
VLAN3 = ID 3 (Production network B)
-------------------------------------------------------
OfficeServer1 must be connected to VLAN1 (Port 01)
OfficeServer2 must be connected to VLAN1 (Port 02)
AppServer 1 must be connected to VLAN2 (Port 03)
AppServer 1 must be connected to VLAN3 (Port 04)
-------------------------------------------------------
PORT 01 : UNTAGGED VLAN1 (ID 1)
PORT 02 : UNTAGGED VLAN1 (ID 1)
PORT 03 : UNTAGGED VLAN2 (ID 2)
PORT 04 : UNTAGGED VLAN3 (ID 3)
...
...
...
PORT 52 : TAGGED (VLAN1-VLAN2-VLAN3) (Distribution port)
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